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Can you see three trees from your home, school or workplace? Is there tree canopy cover shading at least 30% of the surrounding neighbourhood? Can you find a park within 300 metres of the building?

These three simple questions form the basis of the “3+30+300 rule” for greener, healthier, more heat tolerant cities. This simple measure, originally devised in Europe and now gaining traction around the world, sets the minimum standard required to experience the health benefits of nature in cities.

We put the rule to the test in eight global cities: Melbourne, Sydney, New York, Denver, Seattle, Buenos Aires, Amsterdam and Singapore.

Most buildings in these cities failed to meet the 3+30+300 rule. We found canopy cover in desperately short supply, even in some of the most affluent, iconic cities on the planet. Better canopy cover is urgently needed to cool our cities in the face of climate change.

Explore all three interactive maps, zoom in or out and search by address or place, hit the “i” button for more detail. Source: Cobra Groeninzicht

Shady trees are good for health and wellbeing

People are more likely to suffer from depression, anxiety, obesity and heatstroke in places with fewer trees, or limited access to parks. But how much “green infrastructure” do we need to stay healthy and happy?

Dutch urban forestry expert Professor Cecil Konijnendijk set the standard when he introduced the 3+30+300 rule in 2022. This benchmark is based on his wide-ranging review of the evidence linking urban nature to human health and wellbeing.

While the rule is still relatively new to Australia, it is gaining momentum internationally. Cities in Europe, the United States and Canada are using the measure, formally or informally, in their urban forestry strategies and plans. These cities include Haarlem in the Netherlands, Malmö in Sweden, Saanich in Canada, and Zürich in Switzerland.

Putting the rule to the test

We applied the 3+30+300 rule to a global inventory of city trees that collates open source data from local governments. We selected cities with the most detailed data for our research, aiming for at least one city on every continent. Unfortunately no suitable data could be identified for cities in Africa, mainland Asia or the Middle East.

Our final selection of eight cities features several regarded as leaders in urban forestry and green space development. The City of Melbourne is renowned for its ambitious Urban Forest Strategy. New York is home to successful projects such as MillionTreesNYC and The Highline. Singapore is known for lush tropical greenery including standout sites such as Gardens by the Bay and Bishan-Ang Mo Kio Park.

Analysis of Melbourne and Sydney was restricted to central areas only, based on limitations in the data, while the other six analyses covered whole cities.

Most buildings across the eight cities met the three trees requirement but fell short on canopy cover. In contrast, three in four (75%) buildings passed the 30% canopy benchmark in Singapore and almost one in two (45%) passed in Seattle.

Just 3% of buildings in Melbourne had adequate neighbourhood canopy cover, despite 44% having views of at least three trees.

Central Sydney fared better, although only 17% of city buildings were shaded enough despite 84% having views of at least three trees.

Access to parks was also patchy. Cities such as Singapore and Amsterdam scored well on parks, while Buenos Aires and New York City scored poorly.

Since completing this study, we partnered with Dutch geospatial firm, Cobra Groeninzicht to map ten extra cities in Europe, the US and Canada. We found similar results in these cities.

Too small and spaced out

We were surprised to discover so many buildings around the world had views to at least three trees but still had inadequate neighbourhood canopy cover. This seemed contradictory – are there enough trees, or not?

The issue comes up in other studies too. For example, the city of Nice in France recently revealed 92% of residents have views to three trees, but only 45% had adequate neighbourhood canopy.

When we looked into this issue, we found those three trees, visible as they may be, are often too small to create decent shade.

Planting density was an issue too. When a city did have large trees, they tended to be very spaced out.

Meeting the 3+30+300 rule therefore requires bigger, healthier longer-lived trees, planted closer together.

Explore all three interactive maps, zoom in or out and search by address or place, hit the “i” button for more detail. Source: Cobra Groeninzicht

City living is tough for trees

Many of our roads and footpaths sit on a base of compacted crushed rock, topped by impermeable asphalt or paving. This means very little water reaches tree roots, and there isn’t much space for the roots to grow. As a result, street trees grow slowly, die young, and are more susceptible to pests, disease and heat stress.

Above ground, trees face further challenges. Power companies have legal powers to demand sometimes excessive amounts of pruning. Residents and developers frequently request tree removals, often successfully.

This trifecta of high removal rates, heavy pruning and tough growing conditions mean large, healthy canopy trees are rare.

Planting new trees is surprisingly difficult too. Engineering standards often act against tree planting by requiring large clearances from driveways, underground pipes, or even parking spaces.

Instead of managing potential conflicts, trees are often simply deleted from streetscape plans. Sparse planting is the result.

Finding solutions to nurture tree canopy

Fortunately, there are solutions to all of these issues.

Legal reforms to put trees on equal footing with other infrastructure would be a great place to start. Trees do come with risks as well as benefits, but we need to manage those risks rather than settling for hot, desolate streets.

Better planting standards will be important too. Technology already exists to create larger soil volumes under footpaths and roads. Clever asphalt-like materials (often called “permeable paving”) allow rain to infiltrate soils. These approaches cost more, but they work very well. Not only do they potentially double tree growth rates trees, but they also help reduce flood risks and minimise issues such as roots blocking drains or causing bumpy footpaths.

Our study is a clear call to action for cities to expand, maintain and protect their urban forests and parks to prepare for climate change. With another record-breaking summer predicted, hot on the heels of the world’s hottest year, growing tree canopy has never been more urgent. We must push forward with these reforms and ensure our urban populations have all the green infrastructure they need to protect them into the future. 

Thami Croeser, Research Fellow, Centre for Urban Research, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia is a world-leader in species extinction and environmental decline. So great is the problem, the federal government now wants to harness money from the private sector to pay for nature repair.

Under the government’s new “nature repair market”, those who run projects to restore and protect the environment are rewarded with biodiversity credits. These credits can be sold to private buyers, such as corporations wanting to meet environmental goals.

The nature repair market is similar in many ways to Australia’s existing carbon credit scheme. So, examining the extent to which carbon projects actually protect biodiversity is important as the government sets up the nature repair market. This was the focus of our new research.

Alarmingly, we found Australia’s carbon credit scheme largely fails to protect threatened species, despite assumptions to the contrary. The findings provide cautionary lessons for the nature repair scheme.

Spotlight on the carbon credit scheme

Australia’s carbon credit scheme encourages activities that reduce carbon. They include planting trees, reducing animal grazing on vegetation, or retaining vegetation instead of cutting it down.

Project proponents earn credits for carbon reduction, which can then be sold on a carbon market.

The scheme also purports to offer “non-carbon” benefits. These include increasing biodiversity and expanding habitats for native species. Indeed, biodiversity conservation has underpinned the carbon credit scheme since it began in 2011.

But does the carbon scheme actually benefit biodiversity?

To answer this question, we overlaid the locations of carbon-reduction projects with the locations of habitat for threatened plants and animals species. We then scored the level of degradation of each habitat, and identified the processes imperilling the threatened species.

So what did we find? Threatened species most in need of habitat restoration are the least likely to have their habitat restored under the carbon credit scheme.

Projects under the scheme are primarily located in arid parts of Australia not suitable for growing crops – mostly vast cattle grazing leases. Carbon projects here involve inexpensive activities such as removing some cattle or managing weeds.

These areas support habitat for only 6% of Australia’s threatened species. In other words, vegetation loss here generally doesn’t threaten species’ survival.

In contrast, just 20% of carbon projects take place on productive agricultural land which supports nearly half of Australia’s threatened species. In these areas, property values are high and landholders can earn good money from farming. That means carbon-reduction projects are often less financially attractive than other land uses, so their number and size is limited.

So what’s the upshot? Australia’s carbon projects are concentrated in areas containing little threatened species habitat, rather than where threatened species live and most need protecting.

Government policies enable this perverse outcome, by giving preference to projects that can reduce carbon for the lowest cost. This has skewed projects towards unpopulated, relatively unproductive lands.

There’s an upside

It’s not all bad news, however. We found the carbon credit scheme may protect threatened species in some cases.

Almost one-third (or 525) of Australia’s threatened species live in habitat that overlaps with projects under the scheme.

In addition, five species whose habitat is not safeguarded in Australia’s protected areas, such as national parks, may also occur on land where carbon projects take place. A further 270 species with too-little protected habitat also overlap with the projects.

The potential for positive benefits can be seen by looking at the two regions with the largest concentration of carbon projects in Australia.

In the Murchison bioregion in Western Australia, a quarter of species rely on habitat that is not adequately protected elsewhere. In the Mulga bioregion in New South Wales and southwest Queensland, two-thirds of species rely on habitat inadequately protected elsewhere.

Lessons for nature repair

Australia’s nature repair legislation came into effect in late 2023. It creates a framework for the nature repair market which is expected to launch early next year.

Our findings provide important lessons for this market. Most importantly, they show a lowest-cost approach to generating credits is unlikely to benefit biodiversity. It will drive projects to marginal areas that do not overlap the ranges of species threatened by habitat loss.

If nature repair investment is to prevent species extinctions, the Australian government must ensure taxpayer funds actually achieve these outcomes. The best way to do that is to speed up the progress of promised environmental law reform.

Likewise, as global conservation increasingly looks to private finance and biodiversity markets, we must ensure funds are delivered to where they are most needed.

Penny van Oosterzee, Adjunct Associate Professor James Cook University and University Fellow Charles Darwin University, James Cook University and Jayden Engert, PhD Candidate in Applied Ecology, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Humans have been turning wild animals into pets for thousands of years. Pets – animals kept for companionship, not for food or work – were widespread in ancient Egypt.

In Australia, First Nations groups favoured dingoes, a naturalised canine arriving perhaps 5,000 years ago. “Dingo” is derived from din-gu, the Dharug word for domesticated dog – wild dingoes were known as “warrigal”.

To begin with, early colonial settlers often saw native wildlife as competitors to livestock. But over time, some began keeping native animals as pets. In the early 20th century, officials began warning people not to take animals such as koalas from the wild to become pets. Over the next few decades, state and territory governments restricted the practice.

A few common native species such as budgies can be kept without a license regardless of where you live. But having a pet koala is either banned outright or heavily restricted.

In recent years, states such as South Australia have moved to liberalise native wildlife ownership laws. Could this be good for threatened species? That depends. Turning threatened species into pets may keep the species alive – but unable to survive without us.

What wildlife can be kept as pets in Australia?

These days, most Australian pet owners have a dog or a cat and wouldn’t think to consider a native pet other than a budgie. Is it even legal, you might wonder. Well, it depends where you live.

In South Australia you can keep most native animals as a pet, though you might need a permit depending on the type.

Residents keep animals such as fat-tailed dunnarts, sugar gliders, rufous bettongs, and a long list of reptiles and birds – even emus. But there are rules – native pets have to be sourced from captive populations, not the wild.

In Queensland you can keep species such as black-throated finches, types of rainbowfish and crimson rosellas without a licence. A standard licence opens the door to bird-eating spiders, tree frogs, land mullet and bearded dragons.

Other states and territories list a few dozen common species which you don’t need a license to keep.

• In the Northern Territory residents can keep species such as spinifex hopping mice without a permit.

• In Victoria residents have to get a license for all native species bar 45 common ones such as king quail, blue-tongue lizards and spinifex hopping mice.

• In New South Wales residents have a similar list of 41 common species and license requirements for others.

• In Western Australia, residents can keep any invertebrate as a pet, as well as 12 bird species. A standard license opens the door to dozens of bird and reptile species.

• Tasmania is more restrictive. Rainbow lorikeets, turtles, snakes and ferrets are banned as pets. The island state wants to avoid issues with introduced species – and even native species such as sugar gliders can do real damage once they’re introduced.

The rules can be quite different overseas. The sugar glider is largely restricted to permit-holders in Australia, but is commonly kept as a pet in the United States without restrictions. Similarly, you can buy a kangaroo as a pet in some US states.

Wild pets can be hard work

Cute, furry gliding marsupials like sugar gliders make for great social media content. But sugar gliders are nocturnal and have specialised diets. They’re not an easy pet.

Most Australian species will pose similar challenges. Special diets. Different waking hours. The need for specific types of enclosures and enrichment.

If a native pet is fed the wrong food, such as fruits high in sugar, they can quickly become overweight, ill and have dental problems.

Some species like gliders also have complex social structures which can be tricky to manage, and without suitable companions may become stressed or depressed.

Could domestication help conservation?

It’s not uncommon to hear people asking whether keeping threatened native species as pets could help bring them back from the brink.

Conservationists have long used captive breeding to boost dwindling populations and reintroducing captive-born individuals back to the wild. Not long ago, the eastern barred bandicoot was extinct in the wild in Victoria. But a sustained captive breeding and release program on fox-free islands has been remarkably successful.

But conservation projects like this are done carefully. They need strict breeding, genetic and health management, alongside significant funding and planning commitments. Some animals undergo antipredator training to give them a better chance in the wild.

Using native pets for conservation is a different story.

When animals are domesticated, their anatomy and appearance begins to change. We select pets for a range of appealing traits, resulting in a wide variety of coat colours, body shapes and temperaments. This is how we ended up with hundreds of varieties of dogs.

In Russia, foxes bred in captivity ended up with floppy ears and different coat patterns. The budgerigar is one of the world’s most popular pet birds. But captive breeding over 150 years has produced pet budgies generally larger and slower than wild individuals.

What if we had pet quolls not cats?

Conservationists have floated the idea of having pet quolls rather than pet cats. Quolls are attractive, carnivores with unique coats, similar in size to cats. But all four species of these native marsupials are under pressure.

If we bred quolls for pet shops, we would likely see them change, as our preferences change how they look and behave. Bitey or drab quolls wouldn’t get to mate. This selection process has already happened to sugar gliders – you can now buy gliders with pure white coats. That’s good for humans – but not for the species.

Within 13 captive-bred generations, the northern quoll loses its wariness and other defences against predators. Animals bred for pets would likely find it hard or impossible to survive the wild.

Making animals into pets doesn’t mean wild populations will increase. Around 5,000 tigers now live in captivity in the US, more than those remaining in the wild. But “pet” tigers are rarely reintroduced back to the wild. So wild tiger populations keep falling even while domesticated tiger numbers grow.

So yes, keeping native species as pets could safeguard against complete extinction. But it’s hard to see how owning a pet quoll or other native species would help the species overall.

Meg Edwards, Lecturer in Wildlife Science, University of Southern Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Perth is no stranger to hot and dry summers, but the period from October 2023 to April 2024 was exceptional. The city’s rainfall for these seven months was only 23 millimetres, the lowest since records began in the 1870s. It was also one of the warmest summers on record, with temperatures 1.7°C higher than the long-term average.

The “canary in the coalmine” is a metaphor for an early warning that something is wrong. In this case, though, it wasn’t the birds that first alerted us. Rather, we saw the drought’s impacts on our iconic and unique vegetation.

Jarrah, marri, karri and banksia trees, some as old as 100 years, began to die. The die-offs created a mosaic of brown patches across 1,000 kilometres of south-west Australia’s otherwise green forest.

The region’s ecosystems are diverse and complex. As the drought took hold, there were more subtle changes beyond the visible tree deaths. Perth has a community of avid birdwatchers who began noticing bird species rarely seen in the city, or known to be infrequent visitors.

We analysed bird observation data from the global citizen science platform, eBird, to determine which species had increased in the Perth metropolitan area at this time. We found a dramatic spike in reporting rates for four species – the black-shouldered kite, black-tailed nativehen, tawny-crowned honeyeater and western spinebill. Some species were reported up to nine times more than usual.

Birds sought refuge in the city

These shifts hint at how extreme weather can push wildlife into new and unexpected spaces.

The black-shouldered kite, a nomadic bird of prey, is often found in heath and woodlands in south-western Australia, as well as in rural landscapes. The black-tailed nativehen is more commonly associated with inland wetlands but is known to appear suddenly in large numbers in new habitats and then disappear just as quickly. Honeyeaters, such as the tawny-crowned honeyeater and the western spinebill, tend to favour coastal heathlands and forests. So why were they turning up in Perth city?

We suggest it’s likely because the drought stripped their usual habitats of vital resources, particularly food and water.

The city, on the other hand, although also hot and dry at this time, had water in remnant wetlands, the Swan River, artificial lakes and ponds, and people’s gardens. These areas may also have nectar-rich plants for the honeyeaters, insect populations perhaps eaten by the black-tailed nativehen, and rodents or rabbits for the black-shouldered-kite. We think these urban environments became temporary refuges, providing a different water and food source for these birds.

A long history of bird immigration

This isn’t the first time birds have flocked to Perth during challenging environmental conditions.

Galahs, for example, were confined historically to inland areas. Early explorers such as John Gould and John Forrest noted their absence around the Swan River colony. They weren’t common in this area until after the second world war, following a series of dry years.

In many cities in Australia, cockatoos are known to take advantage of watered lawns, sports fields, parks and artificial lakes in cities. These resources have created a novel urban habitat for these birds.

This also happens in rural towns. Parrots, birds of prey and our beloved “bin chickens” (white ibis) have increased in these towns as inland rainfall declines.

The short-term movement of species such as the black-shouldered kite, western spinebill and tawny-crowned honeyeater into cities represents a new chapter in this urban immigration story. Perhaps we should expect more drought migrants as the climate crisis continues to impact their natural habitats.

On the front-line of climate change

South-west Western Australia is a global biodiversity hotspot. It is also considered one of the most climate-vulnerable regions in the world.

In Perth, annual rainfall has decreased by around 130mm (15%). That’s a drop from about 860mm to 730mm over the past 30 years (1993–2023) compared to the previous 30 years (1959–1988).

This long-term drying trend, combined with rising temperatures, puts immense pressure on the ecosystems local wildlife depends on. The drought event of 2023–24 may be a precursor of what’s to come. More research is needed to understand the movements of birds and other wildlife in response to these events.

To the relief of those watching the landscape turn brown, it started raining in May 2024. We bought ourselves a rain gauge to celebrate, and waited to see what the next months of eBird data would reveal. The data showed all four drought immigrants retreated from the city almost as quickly as they had arrived.

This movement supported the theory that these birds were using the city only as a temporary refuge during the harshest drought months.

Observations of unusual bird behaviour highlight the complex relationship between wildlife and urban environments under climate stress. While cities may offer some refuge, they are not a long-term solution for wildlife facing habitat loss. Indeed, the spread of urban areas poses its own major threats to bird communities.

As the climate crisis intensifies, integrating urban areas into conservation plans could be crucial for supporting species during extreme events. Individuals, councils and urban planners may be able to increase the quality of the refuges in cities in relatively simple ways. Planting more native vegetation and providing safe water sources for visiting wildlife would be a good start.

Harry Moore, Adjunct Research Fellow, School of Agriculture and Environment, The University of Western Australia and Anna Cresswell, Adjunct Research Fellow, UWA Oceans Institute, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

A vast network of ocean currents nicknamed the “great global ocean conveyor belt” is slowing down. That’s a problem because this vital system redistributes heat around the world, influencing both temperatures and rainfall.

The Atlantic Meridional Overturning Circulation funnels heat northwards through the Atlantic Ocean and is crucial for controlling climate and marine ecosystems. It’s weaker now than at any other time in the past 1,000 years, and global warming could be to blame. But climate models have struggled to replicate the changes observed to date – until now.

Our modelling suggests the recent weakening of the oceanic circulation can potentially be explained if meltwater from the Greenland ice sheet and Canadian glaciers is taken into account.

Our results show the Atlantic overturning circulation is likely to become a third weaker than it was 70 years ago at 2°C of global warming. This would bring big changes to the climate and ecosystems, including faster warming in the southern hemisphere, harsher winters in Europe, and weakening of the northern hemisphere’s tropical monsoons. Our simulations also show such changes are likely to occur much sooner than others had suspected.

Changes in the Atlantic Meridional Overturning Circulation

The Atlantic ocean circulation has been monitored continuously since 2004. But a longer-term view is necessary to assess potential changes and their causes.

There are various ways to work out what was going before these measurements began. One technique is based on sediment analyses. These estimates suggest the Atlantic meridional circulation is the weakest it has been for the past millennium, and about 20% weaker since the middle of the 20th century.

Evidence suggests the Earth has already warmed 1.5ºC since the industrial revolution.

The rate of warming has been nearly four times faster over the Arctic in recent decades.

Meltwater weakens oceanic circulation patterns

High temperatures are melting Arctic sea ice, glaciers and the Greenland ice sheet.

Since 2002, Greenland lost 5,900 billion tonnes (gigatonnes) of ice. To put that into perspective, imagine if the whole state of New South Wales was covered in ice 8 metres thick.

This fresh meltwater flowing into the subarctic ocean is lighter than salty seawater. So less water descends to the ocean depths. This reduces the southward flow of deep and cold waters from the Atlantic. It also weakens the Gulf Stream, which is the main pathway of the northward return flow of warm waters at the surface.

The Gulf Stream is what gives Britain mild winters compared to other places at the same distance from the north pole such as Saint-Pierre and Miquelon in Canada.

Our new research shows meltwater from the Greenland ice sheet and Arctic glaciers in Canada is the missing piece in the climate puzzle.

When we factor this into simulations, using an Earth system model and a high-resolution ocean model, slowing of the oceanic circulation reflects reality.

Our research confirms the Atlantic overturning circulation has been slowing down since the middle of the 20th century. It also offers a glimpse of the future.

Connectivity in the Atlantic Ocean

Our new research also shows the North and South Atlantic oceans are more connected than previously thought.

The weakening of the overturning circulation over the past few decades has obscured the warming effect in the North Atlantic, leading to what’s been termed a “warming hole”.

When oceanic circulation is strong, there is a large transfer of heat to the North Atlantic. But weakening of the oceanic circulation means the surface of the ocean south of Greenland has warmed much less than the rest.

Reduced heat and salt transfer to the North Atlantic has meant more heat and salt accumulated in the South Atlantic. As a result, the temperature and salinity in the South Atlantic increased faster.

Our simulations show changes in the far North Atlantic are felt in the South Atlantic Ocean in less than two decades. This provides new observational evidence of the past century slow-down of the Atlantic overturning circulation.

What does the future hold?

The latest climate projections suggest the Atlantic overturning circulation will weaken by about 30% by 2060. But these estimates do not take into account the meltwater that runs into the subarctic ocean.

The Greenland ice sheet will continue melting over the coming century, possibly raising global sea level by about 10 cm. If this additional meltwater is included in climate projections, the overturning circulation will weaken faster. It could be 30% weaker by 2040. That’s 20 years earlier than initially projected.

Such a rapid decrease in the overturning circulation over coming decades will disrupt climate and ecosystems. Expect harsher winters in Europe, and drier conditions in the northern tropics. The southern hemisphere, including Australia and southern South America, may face warmer and wetter summers.

Our climate has changed dramatically over the past 20 years. More rapid melting of the ice sheets will accelerate further disruption of the climate system.

This means we have even less time to stabilise the climate. So it is imperative that humanity acts to reduce emissions as fast as possible.

Laurie Menviel, Post-doctoral Research Fellow, Climate Change Research Centre, UNSW Sydney and Gabriel Pontes, Post-doctoral Research Fellow, Climate Change Research Centre, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The way we organise our cities and regions creates problems everywhere. We’re facing difficult and polluting drives to work, a lack of affordable housing, and urban designs that lead to car dependency and are bad for our health.

For example, poor levels of walkability are associated with higher rates of obesity, hypertension and cardiovascular disease. Parks and greenery are associated with better mental and cognitive health.

Australian cities sprawl. Many suburbs are hard to get to by public transport or cycling and walking.

Our sprawling cities use a lot of land per person. Their resource use and carbon footprints are massive. They also produce huge amounts of waste.

To resolve such issues, government planners should think beyond our capital cities. Australia needs to develop strategies that connect these capitals with surrounding regional cities to create “megacity regions”.

It’s a settlement model that could work better than our big cities do now, making urban growth more sustainable. The emergence of hybrid work, fast internet and high-speed rail favours this form of settlement.

What are megacity regions?

A megacity region, according to the OECD, is a network of urban areas linked to a capital city by home-to-work commuting. Megacity regions connect these urban centres more efficiently to make them more sustainable and productive.

An early example is the Bos-Wash corridor (including Boston, New York, Philadelphia, Baltimore and Washington DC) in North America that emerged around the mid-20th century. Megacity regions are now common across Europe (for example, Germany’s Rhine-Ruhr region including Dortmund, Essen, Duesseldorf and Cologne, and the Netherlands’ Randstad region including Amsterdam, The Hague, Rotterdam and Utrecht). The Taiheiyō Belt in Japan (including Tokyo, Nagoya, Osaka, Hiroshima and Fukuoka) is one of many Asian examples.

How ready is Australia for megacity regions?

The 2019 CSIRO Australian National Outlook explored the question “What will Australia be like economically, socially and environmentally in 2060?” Its modelling showed “stronger regions” created major benefits across transport, health, education, jobs and housing. One scenario involved 16 million people living in regional Australia by 2060, with 10 million in regional cities.

CSIRO concluded that “investing in the growth of regional satellite cities with strong connectivity to those capitals” creates many opportunities. This growth would benefit the regions while easing pressures on the capitals.

In recent years, the New South Wales government has developed ideas for Sydney to grow into a Six Cities Region from Newcastle to Wollongong.

The Committee for Melbourne has called for an Australian East Coast Megaregion to boost economic growth and attract foreign investment.

In 2023, the Victorian government indicated a statewide strategy, Plan Victoria, would replace Plan Melbourne.

However, without robust regionalisation policies, Melbourne and Sydney are likely to become sprawling megacities of ten million people or more this century. This will add to the strain on transport, infrastructure and housing.

What makes change possible?

Cities and their central business districts are important for their agglomeration effects – the accumulated benefits of concentrated social and economic activity. But this also often leads to social, economic and environmental problems.

Integrating regional cities into the economic life of their capital cities can reduce some of these problems. It can also produce many benefits, including new and more efficient industries, enhanced communication networks and stronger labour markets.

Settlement systems have evolved throughout history. Walking cities became rail-oriented cities, which became car-based cities. All these models in their day supported a daily return commute averaging one hour (Marchetti’s constant).

Our research explores how new technologies and work practices can enable a fourth transition to the megacity region. The drivers of this change include ubiquitous fast internet, hybrid work and high-speed rail.

Ubiquitous fast internet

NBN broadband data from 2012 to 2021 showed little difference between Melbourne and Victorian regional cities in the uptake of typical residential internet connections. There was a major difference for higher-speed business connections.

Major capital cities continue to act as engines of bandwidth-hungry, information economy industries in Australia. They have more high-skilled workers and higher uptake of fast internet.

Overall, the data reflected that regional cities in Victoria mostly house “population-serving” rather than “producer-services” industries. Fast internet can open up job opportunities, but is not by itself enough to decentralise knowledge industries.

Hybrid work

Working both from home and in the office has become established since COVID. Hybrid work improves sustainability, mostly by reducing car use and road congestion.

Today, only 18% of Australian knowledge workers work “only in the office”.

Not having to go into work every day means knowledge workers can live further from their workplace. This changes the employment landscape in regional centres. Many information economy jobs can be done in non-metropolitan locations where housing costs less.

High-speed rail

Fast rail systems have long been debated in Australia, with various options proposed.

Victoria introduced “faster” regional rail in 2005-06. The populations of urban centres served by these lines have since grown faster than “off-line” ones.

The gap in job growth rates between on-line and off-line centres was greater for producer services than people-serving jobs. The latter are tied more closely to demand from local residents.

Designated growth areas on the outer fringes of Melbourne had much higher population and employment growth rates, indicating that current transport polices have supported urban sprawl. High-speed rail can help urban growth to “leap over” outer suburbs to the regional cities.

What could high-speed rail lead to? In England, the advent of high-speed rail (speeds of more than 200km/hr) resulted in notably higher population growth in on‑line local area districts compared to off-line. The on-line districts, across the board, experienced a stronger shift towards information and knowledge-based industries than off-line ones. Some even outperformed outer metropolitan London districts.

Why is this important now?

Both federal and Victorian governments are preparing strategic plans to guide long-term urban development. Both have issued discussion documents for public feedback.

These documents are long on planning principles but short on mission-scale programs capable of transformative change. This sort of change is now the focus of long-term planning internationally. Land-use planning of megacity regions needs to feature strongly in Australian urbanisation plans too.

We have a once-in-a-generation opportunity to achieve urban development at a scale and in a form that can transform Australia’s settlement system.

Peter Newton, Emeritus Professor in Sustainable Urbanism, Centre for Urban Transitions, Swinburne University of Technology; James Whitten, Research Fellow, Department of Architecture, Monash University; Magnus Moglia, Associate Professor in Sustainability Science, Swinburne University of Technology, and Stephen Glackin, Senior Research Fellow, Centre for Urban Transitions, Swinburne University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The megafires that tore through Australia’s forests in 2019–20 burnt more than ten million hectares. The tragedy prompted a massive research effort to understand how plants and animals were affected.

So what did it uncover? Research published today in the journal Nature set out to answer that question. In a collaboration involving more than 100 scientists, we brought together data for more than 1,300 animal and plant species. As far as we know, it’s the world’s largest dataset of biodiversity responses after a single fire season.

We found populations of some species declined, while other species became more common after the fires. Importantly, the results depended strongly on the condition of the land before the fire – especially how frequently it had been burned before the megafires.

The findings have profound implications for how Australia manages its natural environments. Authorities often use frequent fuel-reduction burning to prepare for bushfires – however our findings suggest this primes ecosystems for major disruption when the next wildfire hits.

An unparallelled opportunity

Global warming and other human-caused changes are driving more frequent and severe bushfires around the world. In the past 20 years, extreme fires have doubled globally. This in turn is helping fuel Earth’s species extinction crisis.

After Australia’s 2019-20 fires, rapid assessments estimated almost 900 plant and animal species were severely impacted, or put at heightened extinction risk from future fires. In response, government and non-government organisations allocated hundreds of millions of dollars for field-based monitoring and recovery.

This extraordinary monitoring effort provided an unparalleled opportunity to measure how extreme fires affect biodiversity.

We collated 62 sets of data involving 810,000 records of the presence, absence or abundance of species in burnt and unburnt sites.

It covered 1,380 species including plants, birds, frogs, mammals, reptiles, insects and land snails. The records were collected along more than 1,000 kilometres of Australia’s east coast, plus sites in South Australia and Western Australia.

The losers

We found 55% of species declined after the 2019-20 megafires – either because they were less abundant overall or occupied fewer sites.

Species in areas exposed to frequent or recent past fires struggled the most. Sites that experienced three or more fires in the 40  preceding years had declines up to 93% larger than with sites not burnt, or burnt once over the same period.

Too-frequent bushfires can mean plants don’t have enough time between fires to set seeds. It can also wipe out valuable animal habitats such as logs, dead trees and tree hollows.

Among all the animal and plant groups that we examined, mammals were the most sensitive, showing average declines twice as large as other groups.

Mammals may be too large to shelter in the small burrows and crevices that smaller animals can squeeze into, they cannot fly to escape the flames, and naturally require more food because they are warm-blooded.

The winners

Some 45% of species were more commonly found in burnt sites after the megafires. The size of increases generally mirrored the size of declines in other species under the same conditions.

The most important example relates to fire frequency. Sites burnt frequently experienced both the largest declines and largest increases after the 2019-20 fires.

There are several ways frequent fire before the megafires could allow species to increase.

Species that re-establish quickly after a fire could have large populations before the next fire. This means more individuals could survive the fire, leading to successively larger populations.

And if individuals do survive a fire, their living conditions may become easier if, say, their predators did not survive, or there is less competition from other animals for resources.

Some plants may become increasingly abundant after each successive fire, such as grasses, benefiting animal species that eat or shelter in them.

This is not to say that megafires are good for biodiversity overall, or that more abundant species balance out the losses.

The species that do well after fire will continue to thrive as recently burnt areas become more common. That’s great, but the declining species will become an increasingly severe problem for conservation.

The decline is also a big problem for humans, who depend on biodiversity for a range of services.

A rethink is needed

Bushfire management agencies aim to reduce fire risks through frequent fuel-reduction burning. This involves a program of deliberately burning blocks of native vegetation at relatively short intervals, to reduce flammable materials such as plants, fallen branches, logs, twigs, leaves and bark.

But our research suggests this practice, which increases fire frequency, may create larger disruptions to ecosystems when big bushfires occur.

Past research has found that bushfires can be less severe when fuel-reduction burning has been undertaken in the three to five years prior.

And in some cases, when fuel-reduction burning was recent and nearby, it can help protect infrastructure from fire.

But our findings indicate even if a bushfire is not particularly severe, the harm to plants and animals can be extreme when sites have been burnt three or more times over 40 years, or within the ten preceding years.

So, frequent fuel-reduction burning, combined with any other preceding bushfires, condemns many plants and animals to large, potentially catastrophic declines in the next bushfire.

Clearly, fire management and policy needs a big rethink. Alternative approaches to large-scale prescribed burning are required.

This could include developing the skills and technologies to rapidly detect and suppress bushfires. It may also involve supporting Indigenous “right-way fire”, a culturally informed method of fire management.

Encouragingly, we found severe bushfire impacts could be moderated if a lot of unburnt habitat exists within 2.5 kilometres. This allows plant seeds and animals to move from unburnt to recently burnt habitats, helping the damaged area to recover.

So, fire managers should protect remaining unburnt patches after fire, rather than burning them to prevent later flare-ups. If unburnt patches can be retained while fires are being fought, native communities will be able to recover more rapidly.

However, we should not forget that Australia’s 2019-20 megafires were the predictable consequence of climate change.

The alternative fire management approaches we suggest will likely fail if climate change continues unabated.

Don Driscoll, Professor in Terrestrial Ecology, Deakin University and Kristina J Macdonald, Postdoctoral research fellow, Charles Darwin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Warning: this article contains graphic images some readers may find distressing

The beloved koala is now endangered in New South Wales, Queensland and the Australian Capital Territory. The tree-dwelling marsupial is threatened by land clearing, loss of its favourite eucalypts, chlamydia, being preyed on by feral animals and – last but not least – collisions with vehicles.

To arrest the steady decline of koala populations, we must focus on where these animals are being wiped out in front of our eyes.

In Central Queensland, there’s a known koala death hotspot. The Peak Downs Highway connects Mackay on the coast with the Bowen Basin coal mining region. Cars and trucks travel along the highway at speed. The road is notoriously dangerous for humans, with a death toll in the dozens. But it’s also lethal for koalas.

How many are killed? Throughout 2023, citizen scientist and honours student Charley Geddes and our team of scientists counted 145 otherwise healthy koalas struck and killed along a 51 kilometre stretch of this highway. This is a huge figure. By contrast, an average of 365 koalas are admitted to veterinary hospitals each year after being hit by a vehicle across the entire south-east Queensland region.

A roadkill hotspot is a problem that can be solved. In other areas, state and territory governments have built overpasses or underpasses, usually alongside wildlife exclusion fencing to guide the animals to safe passage. In some instances, rope bridges have been installed high above highways.

Unfortunately, there’s very little funding to tackle roadkill hotspots in Central Queensland. Koala conservation efforts by the state government have, to date, focused almost exclusively on south-east Queensland. Our horrifying data shows that must change.

Pity the Central Queensland koala

In Queensland, modelling suggests land clearing and climatic change will gradually drive koalas from the drier west to the wetter east, near the coast.

Koalas are holding out in wetter, more intact refuges such as the Clarke-Connors Range, a coastal mountain range inland from Mackay. These mountains are now home to a significant koala population and, potentially, one of national importance.

Unfortunately, this koala haven has one major problem: fast-moving vehicles. The Peak Downs highway runs directly through this prime koala habitat.

When koalas go roaming for food or to find a mate, they often cross the highway. These exploring koalas are typically male.

What makes this stretch of highway particularly lethal for koalas is the fact the habitat is in good condition. Good land management by some local graziers has meant many eucalypts have been conserved, benefiting koalas and other wildlife. This has been done deliberately, as these trees provide shade for grazing animals. The gum trees koalas prefer – blue gums and ironbarks – are found all along the highway. As a result, we found koalas were being killed nearly anywhere along the stretch.

As yet, we don’t have a good idea about how many koalas are living in the area. More work needs to be done to get good estimates. But the population must be considerable, due to the numbers dying on the roads.

Fences and underpasses

In urban areas, small patches of koala habitat exist alongside houses, industrial parks, commercial centres, roads and parkland. So koalas tend to be concentrated in small patches. In turn, this means it’s actually easier to help them cross roads – you can direct them to a safe crossing point.

It’s much harder to safeguard koalas along a 51 km stretch of highway, with lots of good quality habitat all along the roadside.

On the plus side, the fact there are fewer private properties (mainly used for grazing cattle) would likely make it easier to negotiate to install road barriers or underpasses and overpasses.

Better still, there is some appetite for change. Many landholders in the area are on record expressing their concern about how many koalas are dying on the highway.

As one landholder told us:

All the local landholders that I know in the area seem to be quite proud and empathetic towards koalas. They are creatures that do not impact grazing operations in any way and are treasured for want of a better term.

Several said the solution was fencing. As one said:

Wildlife fencing is the only way to stop the absolute carnage of these wonderful creatures.

A number of landholders have expressed willingness to host fencing on their land.

In recent years, state road authorities have retrofitted several highway underpasses in an attempt to guide koalas to a safer route under the road. Unfortunately, these efforts have not worked.

Previous studies have shown wildlife exclusion fencing can work, but this has been tested only on a local scale. For the Peak Downs Highway, a much greater length of wildlife fencing would likely be needed to actually direct the koalas to safe passage.

The indirect toll from mining

One major reason why so many koalas die on this stretch of highway is because of the high volume of traffic, much of which is going to and from the coal mines in the Bowen Basin. This geological basin contains Australia’s largest body of coal, and has 48 active coal mines as of 2023. Queensland’s largest export is still metallurgical coal.

The high death toll is clearly an indirect consequence of mining operations.

As koala populations shrink in many areas, wetter mountains in Central Queensland have become a vital refuge. But even here, Australia’s iconic tree-dweller is under threat. Many koalas here have diseases such as chlamydia and koala retrovirus, and specialist care for injured or sick animals is harder to come by in this region.

Authorities have moved to tackle the koala road toll in some regions. But the koalas of Central Queensland have largely missed out. As the iconic species reels from a multitude of threats, making this dangerous highway safer to cross offers one way to stop more koalas from dying, week in, week out.

Rolf Schlagloth, Koala Ecologist, CQUniversity Australia; Charley Geddes, Research technician, CSIRO; Douglas Kerlin, Postdoctoral Research Fellow, Environmental Futures Research Institute, Griffith University, and Flavia Santamaria, Lecturer in Biology, CQUniversity Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Global temperature records are expected to exceed the 1.5 °C threshold for the first time this year. This has happened much sooner than predicted. So can life on the planet adapt quickly enough?

In our new research, published today in Nature, we explored the ability of tiny marine organisms called plankton to adapt to global warming. Our conclusion: some plankton are less able to adapt now than they were in the past.

Plankton live in the top few metres of ocean. These algae (phytoplankton) and animals (zooplankton) are transported by ocean currents as they do not actively swim.

Climate change is increasing the frequency of heatwaves in the sea. But predicting the future effects of climate change is difficult because some projections depend on ocean physics and chemistry, while others consider the effects on ecosystems and their services.

Some data suggest that current climate change have already altered the marine plankton dramatically. Models project a shift of plankton towards both poles (where ocean temperatures are cooler), and losses to zooplankton in the tropics but might not predict the patterns we see in data. Satellite data for plankton biomass are still too short term to determine trends through time.

To overcome these problems, we have compared how plankton responded to past environmental change and modelled how they could respond to future climate changes. As the scientist Charles Lyell said, “the past is the key to the present”.

We explored one of the best fossil records from a group of marine plankton with hard shells called Foraminifera. This comprehensive database of current and past distributions, compiled by researchers at the University of Bremen, has been collected by hundreds of scientists from the seafloor across the globe since the 1960s. We compared data from the last ice age, around 21,000 years ago, and modern records to see what happened when the world has previously warmed.

We used computational models, which combine climate trends with traits of marine plankton and their effect on marine plankton, to simulate the oceanic ecosystems from the last ice age to the pre-industrial age. Comparing the model with the data from the fossil record is giving us support that the model simulated the rules determining plankton growth and distribution.

We found that some subtropical and tropical species’ optimum temperature for peak growth and reproduction could deal with seawater warming in the past, supported by both fossil data and model. Colder water species of plankton managed to drift to flourish under more favourable water temperatures.

Our analysis shows that Foraminifera could handle the natural climate change, even without the need to adapt via evolution. But could they deal with the current warming and future changes in ocean conditions, such as temperature?

Future of the food chain

We used this model to predict the future under four different degrees of warming from 1.5 to 4 °C. Unfortunately, this type of plankton’s ability to deal with climate change is much more limited than it was during past warming. Our study highlights the difference between faster human-induced and slower-paced geological warming for marine plankton. Current climate change is too rapid and is reducing food supply due to ocean stratification, both making plankton difficult to adapt to this time.

Phytoplankton produce around 50% of the world’s oxygen. So every second breath we take comes from marine algae, while the rest comes from plants on land. Some plankton eat other plankton. That in turn gets eaten by fish and then marine mammals, so energy transfers further up the food chain. As it photosynthesises, phytoplankton is also a natural carbon fixation machine, storing 45 times more carbon than the atmosphere.

Around the world, many people depend heavily on food from the ocean as their primary protein sources. When climate change threatens marine plankton, this has huge knock-on effects throughout the rest of the marine food web. Plankton-eating marine mammals like whales won’t have enough food to prey on and there’ll be fewer fish to eat for predators (and people). Reducing warming magnitude and slowing down the warming rate are necessary to protect ocean health.

Don’t have time to read about climate change as much as you’d like?

Rui Ying, Postdoctoral Researcher, Marine Ecology, University of Bristol and Daniela Schmidt, Professor in Palaebiology, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The next major United Nations meeting on climate change, known as COP29, is about to get underway in Baku, Azerbaijan. These annual meetings are the key international summits as the world attempts to address the unfolding climate crisis.

The talks this year are crucial as climate change worsens. In recent years, a series of climate-fuelled disasters and extreme events, from Australia’s bushfires to Spain’s floods, have wrought havoc around the world.

What’s more, the continuing upward trajectory of greenhouse gas emissions suggests the window to limit warming 1.5°C is almost closed. And the re-election of United States President Donald Trump casts a pall over global climate action.

So, let’s take a look at the agenda for this vital COP meeting – and how we can gauge its success or failure.

The big issue: climate finance

COP stands for Conference of the Parties, and refers to the nearly 200 nations that have signed up to the UN Framework Convention on Climate Change.

Like last year’s conference in Dubai, the choice to hold this year’s meeting in Baku is controversial. Critics say Azerbaijan’s status as a “petro-state” with a questionable human rights record means it is not a suitable host.

Nevertheless, the meeting is crucial. COP29 has been dubbed the “finance COP”. The central focus is likely to be a much bigger target for climate finance – a mechanism by which wealthy countries provide funding to help poorer countries with their clean energy transition and to strengthen their climate resilience.

At the Copenhagen COP talks in 2009, developed countries committed to collectively providing US$100 billion a year for climate finance. This was seen as the big outcome of otherwise unsuccessful talks – but these targets are not being met.

The meeting also represents an opportunity to engage the private sector to play a bigger role in driving investment in the renewable energy transition.

But controversial questions remain. Who should be giving money and receiving it? And how do we ensure wealthy countries actually make good on their commitments?

The big outcome from last year’s COP was the establishment of a fund for unavoidable loss and damage experienced by vulnerable states as a result of climate effects. We’ve since seen some progress in clarifying how it will work.

But the US$700 million committed to the fund is far short of what is already required – and finance required is certain to increase over time. One estimate suggested US$580 billion will be needed by 2030 to cover climate-induced loss and damage.

Alongside these issues, the Baku talks will hopefully see some movement on adaptation finance, enabling further funds for building climate resilience in developing countries. To date, contributions and commitments have been well short of the goal set in 2021.

A final issue will be how to clarify rules around carbon markets, especially on the controversial topic of whether nations can use carbon trading to meet their Paris Agreement emission cut targets.

Talks on the latter have been stalled for years. Some analysts see movement on carbon markets as crucial for building momentum for the transition from fossil fuels.

Storm clouds over Baku

By far the biggest shadow over the Baku talks is the election of Republican Donald Trump as United States president.

Trump famously withdrew the US from the climate agreement in 2016, and has declared climate change as “one of the greatest scams of all time”.

Trump’s re-election will significantly affect US cooperation on climate change at a time when the stakes for the planet could barely be higher.

More broadly, geopolitical tensions and conflicts – from Gaza to Ukraine – also risk crowding out the international agenda and undermining the chance of cooperation between key players.

This especially applies to Russia and China, both of which are crucial to international climate efforts.

At past COPs, difficult geopolitics elsewhere haven’t been fatal for cooperation on climate policy – but it does make things harder. For this reason, Azerbaijan has called for a “truce” in global conflicts to coincide with the conference.

National commitments loom large at Baku

This COP represents the last big climate talks before national governments have to publicly state their new emission cut goals – known as “nationally determined contributions” – which are due in February 2025.

A few big players – such as Brazil, the United Kingdom, and the United Arab Emirates – have already indicated they’ll be announcing their new targets at Baku.

There will also be plenty of pressure on other nations to ramp up their targets. That’s because existing commitments put the world far off track to meeting the globally agreed target of limiting planetary warming to 1.5°C – a threshold beyond which devastating climate harms are expected.

The host nation Azerbaijan is also keen to increase transparency around reporting obligations for countries, to make it easier to track progress against emissions targets.

What about Australia?

Australia will almost certainly not be outlining a new emissions target in Baku. It has already signalled it may announce its updated targets after the February 2025 deadline.

For Australia, the main issue at Baku may be whether we – alongside at least one Pacific country – will be announced as the hosts of COP31 in 2026. Australia is tipped to win, but Turkey is a significant competitor.

What does success look like?

Azerbaijan sees agreement on a new collective quantified goal for climate finance as the most important outcome of the conference.

This and other finance outcomes will be important in ensuring a fair distribution of costs from the impact of climate change and the necessary energy transition.

Action on long stalled carbon trading cooperation would also be a win, and could turbocharge the global energy transition.

But real success would come in the form of significant new emissions targets and explicit endorsement of the need to move away from fossil fuels. Sadly, the latter is not prominent on the Baku agenda.

Humanity has run out of time to prevent climate change, and we are already seeing real damage. But an opportunity remains to minimise the future harm. We must pursue urgent and sustained international action, regardless of who is in the White House.

Matt McDonald, Professor of International Relations, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Across the animal kingdom, birds are some of the most colourful creatures of all. But how did all the amazingly coloured different bird species arise?

Nearly all birds with bright red, orange, and yellow feathers or bills use a group of pigments called carotenoids to produce their colours. However, these animals can’t make carotenoids directly. They must acquire them through their diets from the plants they eat. Parrots are the exception to this rule, having evolved an entirely new way to make colourful pigments, called psittacofulvins.

Although scientists have known about these different pigments for some time, understanding the biochemical and genetic basis behind how birds use them to vary in colour has been less clear. But two recent separate studies about parrots and finches have provided vital insight into this mystery.

One study, published in Current Biology, was led by one of us (Daniel Hooper), and the other was led by Portuguese biologist Roberto Abore and published in Science. Together, they advance our understanding of how birds produce their colourful displays – and how these traits have evolved.

A single enzyme

The two new studies involved large teams of international researchers. They used recent advances in genetic sequencing to examine which regions of the genome (an animal’s complete set of DNA) determine natural yellow-to-red colour variation in parrots and finches.

Remarkably, even though these two groups of birds produce their colourful displays using different types of pigments, scientists found they have evolved in similar ways.

Arbore’s study looked at the dusky lory (Pseudeos fuscata), a parrot native to New Guinea with bands of feathers that may be coloured yellow, orange or red. The research found that shifts between yellow and red feather colouring were associated with an enzyme called ALDH3A2. This enzyme converts red parrot pigments to yellow ones. When developing feathers contain large amounts of the enzyme, they end up yellow; when they have less, they end up red.

Scientists found the ALDH3A2 enzyme also explains colour variation in many other species of parrots which have independently evolved yellow-to-red colour variation.

Two special genes

The long-tailed finch (Poephila acuticauda) is a species of songbird native to northern Australia. There are two hybridising subspecies with different coloured bills. One is yellow-billed while the other is red-billed.

Most carotenoid pigments that birds might consume from their diet are yellow or orange, so birds’ bodies must somehow change the chemistry of the pigments after eating them to produce red colours.

Hooper’s study examined variation in this trait across the whole distribution of the long-tailed finch in the wild, and variation in the genomes of the measured birds. It turned out bill colour in these finches was mostly linked to two genes, CYP2J19 and TTC39B.

Together, these two genes drive the conversion of yellow dietary carotenoids to red ones.

In the long-tailed finch, yellow coloration appears to result from mutations that turn these genes off in the bill specifically while keeping them on in other parts of the body, such as the eyes.

By comparing the DNA code of these colour genes to other finch species, the researchers also found the ancestors of the modern long-tailed finch had red bills, but mutant yellow bills have slowly been growing more common.

Like a lightbulb dimmer

Together these studies show how colours can evolve in natural populations.

In both parrots and finches, the mutations responsible for yellow-to-red colour variation did not change the function of the enzymes involved. Instead they influenced where and when these enzymes were active. Think of it as changing the lighting in a room by installing a dimmer on an existing light switch, rather than removing an entire light fitting.

The scientists also showed that in wild populations of both parrots and finches, mutations to just a few genes can alter the chemical structure of the pigments profoundly – enough to make the difference between red and yellow.

The key genes change the chemical structure of the pigment molecule through the actions of an enzyme which adds just one atom of oxygen to the pigment. This changes it from a bright red to a bright yellow in parrots, and the opposite in finches, from bright yellow to bright red.

The wonder of nature

The evolution of colour in birds has been the focus of attention since Charles Darwin used them in outlining his theory of evolution by natural selection. The most obvious difference between the closely related species of birds that we see around us is their colour.

These two new studies have shown us how a few genes and the addition of that single oxygen atom can change the course of evolution, creating a new form that looks so dramatically different. If this improves the animal in an evolutionary sense – perhaps they look more attractive to potential partners or stand out more – it can lead to the origin of a new species.

This work reminds us of the wonder of nature and shows that evolution is an ongoing process.

To conserve species we need to protect as much of their genetic complexity as possible. Every individual in a population contains a unique genome and every small bit of variation is the product of millions of years of evolution in the past. It could also be the key to the development of a new species in the future.

Simon Griffith, Professor of Avian Behavioural Ecology, Macquarie University and Daniel Hooper, Postdoctoral Scholar, Bioinformatics and Computational Biology, American Museum of Natural History

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mangrove forests have been protecting coastlines around the world against erosion and storm surges for millennia. But in 2020, the residents on many islands in the Maldives noticed that many of their mangrove forests were starting to die off. Where once these forests had been lush, now they were turning brown and lifeless.

Our team of scientists has worked closely with coastal communities in the Maldives to investigate that 2020 phenomenon. In our new study, we highlight how mangrove die-off events like this have big implications not just for the Maldives, but also for other island nations and coastal ecosystems around the world.

Mangroves are remarkable trees and shrubs that grow along tropical and subtropical coastlines of more than 120 countries and territories.

Mangroves are carbon powerhouses, storing three to five times more carbon per equivalent area than tropical rainforests. They’re biodiversity hotspots and crucial fish nurseries. For many coastal communities, especially in developing nations, mangroves are essential for food security and livelihoods by providing important protein sources like prawns, crabs and fish.

Mangroves act as natural storm barriers, protecting coastlines from erosion and flooding. For island nations like the Maldives, mangroves are a vital defence against rising seas and storms. So, when over 25% of the Maldives’ mangrove-containing islands died off in 2020, local residents became seriously concerned. Using satellite imagery, we found that some islands lost more than half their mangrove cover.

To investigate potential causes, we examined the wood from affected mangroves. The chemical makeup of mangrove wood can reveal if the trees were struggling with too much salt. Our tests showed that the dead mangroves had been under significant salt stress, meaning they were drowning in saltwater.

Mangroves can typically keep pace with gradually rising seas by building up their own sediment. But when sea levels rise too quickly, and mangroves experience salt stress, this defence mechanism can’t keep up.

Sure enough, our research points to the culprit as being rapidly rising sea levels, supercharged by climate change. The Maldives is the world’s lowest-lying country, with an average elevation of just 1.5m above sea level. This makes it acutely vulnerable to rising sea levels.

We found that from 2017 to 2020, sea levels around the Maldives rose at a rate of over 30mm per year – much faster than the mangroves could build up sediment to stay above water. This rapid rise was linked to a climate phenomenon called the Indian Ocean dipole, which was unusually intense between 2019 and 2020.

Discovered in the late 1990s, the Indian Ocean dipole is a climate pattern which causes changes in wind, sea surface temperature and rainfall across the Indian Ocean basin.

During a positive phase, like between 2019 and 2020, countries in the western Indian Ocean, including the Maldives, experience warmer sea surface temperatures and an increase in sea level as the ocean expands. Meanwhile, the eastern Indian Ocean experiences cooler waters and a drop in sea level.

During a negative phase, this pattern is reversed. Worryingly, some studies suggest that climate change could increase the frequency and severity of future Indian Ocean dipole events, although more research is needed to reduce the uncertainties of these projections.

Signalling a global threat

This is a warning for coastal areas worldwide. As climate change and extreme events intensify, some mangrove forests around the world may struggle to keep up with rising sea levels.

The consequences could be serious. Losing mangroves doesn’t just remove a vital coastal defence – it could release large amounts of stored carbon, further accelerating climate change.

Our study of these Maldives’ mangroves illustrates how climate change can push natural systems past their limits, with cascading negative consequences for both nature and people. Mangroves do go through phases of natural die-off, but our evidence suggests that this event was unusual.

What happened in the Maldives is a reminder that the impacts of climate change are not evenly distributed. Small island developing states, which have contributed less than 1% to global greenhouse gas emissions, are on the front lines of climate impacts.

Natural recovery after a die-back is possible. We saw signs of this in the Maldives as seedlings and new trees were beginning to appear. Since 2020, a much more salt-tolerant mangrove species has become dominant here because it was able to handle the saltier conditions. While this regrowth is encouraging, there are some trade-offs as the shifts in species affect habitat structure, plant productivity and food security.

For example, people often eat the fruits of low salt-tolerant mangrove Bruguiera cylindrica, so the loss of this species has a negative impact on a staple food source. Future episodes of rapid sea level rise could also push even these more salt-tolerant species beyond their limit, potentially leading to more widespread and permanent mangrove loss.

As our planet continues to warm, events like the Maldives mangrove die-off may become more common. The fate of mangroves in the Maldives and other low-lying coastal areas will be a key indicator of how well countries are managing the climate crisis. Mangrove forests have thrived at the interface of land and sea for centuries. Whether they can survive the rapid changes of the coming decades will depend largely on our actions today.

Don’t have time to read about climate change as much as you’d like?
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Vasile Ersek, Associate professor in Physical Geography, Northumbria University, Newcastle and Lucy Carruthers, Postdoctoral Researcher, Department of Coastal Studies, East Carolina University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This year, dozens of new models of electric vehicles have hit the Australian market – and more are coming. New models of battery electric and plug-in hybrids come with bigger batteries. The average battery electric now has a range of over 400 kilometres.

But until now, there’s been a missing piece of the puzzle. The batteries in most new electric cars are huge – much larger than a typical home battery. A BYD Seal might have a battery capacity of 60 to 80 kilowatt hours (kWh), while the average home battery installed in Australia is 11 to 12 kWh.

So why can’t you plug your car in and power your house?

Soon, you will be able to. The suite of technologies already exists. They’re known as vehicle to grid (V2G, where you export power to the grid), vehicle to house (V2H, where you run your house off your car) and vehicle to load (V2L, where you run electric devices off your car).

There’s a cost – you need a bidirectional charger able to send power both to and from the car. But experts expect substantial benefits.

With V2G, you can sell power back to the grid at peak times, helping the grid stay stable. With V2H, you can weather power outages or even go off grid. V2L would be useful for campers and tradies.

One reason it’s not here already is that regulations and processes haven’t been in place. On Saturday, climate change minister Chris Bowen announced progress on this front. Vehicle to grid would be up and running by Christmas. That’s a very ambitious timeline, as there’s more to it than just regulations. But it is a jump forward.

“When you pick your next EV you won’t be buying just a car, you’ll be buying a household battery on wheels,” Bowen has said.

What changed?

Vehicle to grid isn’t totally new in Australia.

In late 2022, South Australia became the first state to greenlight bidirectional chargers in homes. But these chargers only work with two EV models, the electric Nissan Leaf and the plug-in hybrid Mitsubishi Outlander.

So what just changed? Crucial underpinning – the boring but important scaffolding which makes new technology robust and reliable. Specifically, Standards Australia has approved a new standard for bidirectional chargers.

Australian standards are technical standards outlining specifications and guidelines for new technologies. While voluntary, products are expected to meet the relevant standards. A V2G standard will level the playing field and give clarity for owners, grid operators and electric charger manufacturers.

A new standard is a leap forward. But to make V2G a reality will take more action. Car owners have to install bidirectional fast chargers, able to send power both ways. These aren’t cheap, at around A$3,500 a pop. Car companies have to ensure their chargers meet the new standard. And distribution networks have to approve charger models for use on the grid.

Trial projects such as the Realising Electric Vehicle-to-Grid Services in the Australian Capital Territory and the Amber/ARENA trial in New South Wales show we can meet some of the technical requirements. It will take time and money to integrate these changes nationwide.

Why should we be excited about this?

As more car owners go electric, the size of the battery fleet on Australian roads and driveways is growing fast.

Without V2G, these batteries are just used for one thing – to make a car, truck or bus operate. But these batteries could do much more. Australia’s electric fleet is now over 180,000. If the average battery pack size was 50 kWh, that would represent a giant distributed battery of 9 gigawatt hours. The largest grid-scale battery under construction in Australia will have 2.4 gigawatt hours.

For energy authorities, this fleet of batteries presents a huge opportunity. At times of peak demand, they could offer financial incentives for EV owners to discharge to the grid. Used carefully, EV batteries could avert blackouts. A decentralised power source is more resilient to shocks. It could mean avoiding the need to fire up expensive gas plants at times of peak demand.

For EV owners, the financial incentives could be enough to let their cars be used to keep the grid stable. In testing, early V2G users have been able to turn large power bills into power payments. Annual earnings could be as high as $9-$12,000 per vehicle in New South Wales, according to one report.

Many carmakers are moving towards including V2G.

2025 could be the year

Overseas, vehicle to grid technology is gaining traction. California has mandated V2G capabilities in all light EVs sold from 2027 onward.

In Australia, regulatory change and incentives will be needed to encourage broader adoption.

It’s encouraging to see Australian standards for V2G arrive. But while Bowen is pitching V2G as about to happen, there is still some spadework left to do before it’s really here.

Syed M Nawazish Ali, Research Fellow in Transport Electrification, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Your hot shower or bath uses 15-30% of your household’s total energy, second only to the heating and cooling of air.

More than half of all Australian households rely on electric water heaters with a storage tank. These act like thermal batteries and often store more energy than a home battery. Traditionally, these heaters operated during off-peak hours overnight when power demand was low. This practice also helps maintain stability for coal power stations.

But there’s a better option: cheap heating at daytime. More than 40% of freestanding Australian houses now have solar. Switching water heaters to charge during the day can soak up solar power going to waste – known as curtailment – and make sure electricity supply and demand match.

In our new real world trial, we put this technique to the test and found it works.

From propping up coal to soaking up solar

Electric water heaters have traditionally be set to operate off-peak. On your electricity bill, it would be listed as a “controlled load” item. Switching from night to day isn’t as easy as flicking a switch. It’s often hardwired.

The solution: use smart meters. Almost all Victorian households (99.6%) and most Tasmanian (79%) have smart meters, while other states sit around 35-40%, according to the Australian Energy Regulator. By 2030, every Australian household is projected to have one.

Smart meters can do more than just monitoring use – they can remotely control appliances such as electric water heaters.

Electricity retailers or distribution network operators could offer to change the times of hot water heating via smart meters. Consumers could approve this change and it could be done remotely.

For this to become a reality, the method has to be tested in trials like ours.

Why does this matter?

In October this year, rooftop solar met 18% of Australia’s electricity demand.

One problem with the rooftop solar boom is matching supply with demand. Solar power peaks in the middle of the day but household demand is highest in the afternoon and evening, as people return from work and school.

When there’s more solar power than a household can use, it returns to the grid. Scaled up, this creates new challenges, such as minimum network demand, where floods of cheap solar can destabilise the grid or overload its voltage, forcing authorities to temporarily stop or reduce households sending their solar power back to the grid. That’s where heating water could help – by soaking up excess solar.

What did we learn?

To do real-world testing, we enrolled 18,000 South Australian households with smart meters and electric water heaters. The trial was funded by the Australian Renewable Energy Agency and led by metering company PLUS ES in collaboration with energy retailer AGL and the University of New South Wales.

Over the course of a year, the retailer shifted close to 50% of the water heating from night to day. Most householders reported no noticeable change to their hot water. Only 0.3% of households opted out. Participating households cut their emissions from water heaters by about 15%.

Energy retailers buy power at wholesale prices from generators. Nighttime power used to be cheapest. But daytime rates are falling as solar floods the grid. In the trial, the retailer’s use of daytime power produced savings of A$63 per household. We would expect these savings to increase as more renewables enter the grid.

At present, these savings go to the retailer. But as cheap solar pushes out other forms of power, we are seeing this ripple through to cheaper daytime rates which should be offered by retailers to consumers. This will allow households to take direct advantage of savings.

DIY water heating has a cost for the grid

At present, most people can’t directly use rooftop solar to heat water. Solar and hot water are generally installed on different circuits, even in households with smart meters.

But about 25% of Australian households have already taken matters into their own hands and opted out of controlled load circuits so they could use rooftop solar to heat water.

This appeals to some consumers, as it can significantly cut their water heating bill, but the extra cost of installing timers or diverters may put others off. Some diverters can also worsen the quality of the power on the grid.

By contrast, if the smart meter method gains traction, retailers and energy authorities would be better able to manage the grid as more renewables enter.

What’s in it for consumers? If retailers pass on savings from cheaper wholesale rates, households would be more likely to take the automated smart-meter control option.

Rooftop solar can lead to household voltage increasing slightly, which makes it harder to export solar and can reduce the lifespan of some appliances. That’s because household inverters need to push voltages higher than the grid to be able to push solar onto the network.

But if water heaters run during the day, they soak up more of the output from rooftop solar and keep voltages lower. Voltage levels in trial households dropped by an average of 2.6V, or up to 3.4V for homes regularly experiencing high voltages.

The trial also showed water heating demand could be predicted very accurately, benefiting network operators in day-ahead planning and operations.

What’s next?

Now that we have real-world evidence this method works, authorities can think bigger.

If smart meters were taken up across Australia’s main grid, the National Electricity Market, we could shift 3.8 terawatt hours of electricity use from night to day. That would represent 1.4% of our current electricity consumption of 273 TWh.

At present, about 2.3 TWh worth of utility-scale solar is curtailed annually. Far better to use it to heat water at daytime.

Would this approach work for heat pumps? Yes, with caveats. Heat pumps use electricity to heat water much more efficiently than older heaters. They do, however, require longer heating times. Our trial suggests heat pumps are largely compatible with smart meter control, but they may need different control strategies.

As ever more renewables enter the grid and more Australian households go electric, many of us will ditch gas hot water systems. These trends mean heating water during the day will be even more valuable.

Baran Yildiz, Senior lecturer in Renewable Energy Engineering, UNSW Sydney and Hossein Saberi, Research Associate in Renewable Energy Engineering, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Samantha Harvey’s Orbital has won the 2024 Booker prize. What it so skilfully and ambitiously exposes is the human cost of space flight set against the urgency of the climate crisis.

While a typhoon of life-threatening proportions gathers across south-east Asia, six astronauts and cosmonauts hurtle around Earth on the International Space Station. Their everyday routine of tasteless food and laboratory work is in stark contrast to the awesome spectacle of the blue planet, oscillating between night and day, dark and light, where international borders are meaningless.

Orbital was written during lockdown when the meaning of home (for those lucky enough to have one) changed forever. There’s a sense in which Harvey’s six astronauts return us to that moment when our homes became prisons and we were forced to contemplate the global effects of a virus that had no respect for national boundaries.

On the International Space Station, borders are only visible on the side of the Earth that is under night and only really as clusters of artificial light which shows cities. Rivers are “nonsensical scorings … like strands of long fallen hair” and “the other side of the world will arrive in 40 minutes” blurring it all.

Russian cosmonaut Anton contemplates US astronaut Michael Collins’ iconic photograph of Apollo 11 leaving the surface of the Moon in 1969 with the Earth beyond. He thinks “no Russian mind should be steeped in these thoughts”, but he is captivated by where the people are in the photograph. Is Collins the only human not to appear in it? Or is he the only human presence we can be sure of?

Shaun has a postcard of Diego Velázquez’s Las Meninas, sent to him by his wife. The painting’s complex composition has been said to create a unique illusion of reality where it is unclear who the subject is. Is it the viewer? The royal child? King Philip IV and Queen Mariana of Spain who are depicted on the wall?

“Welcome,” Shaun’s wife writes on the postcard, “to the labyrinth of mirrors that is human life.” The Italian astronaut Pietro solves the labyrinth with the simple observation that the dog at the child’s side must surely be the subject of the painting. “[It is] the only thing… that isn’t slightly laughable or trapped within a matrix of vanities.” Humans, Shaun concludes, are no big deal.

While we gaze at ourselves and try to “ascertain what makes us different” from a dog, which as French theorist Michel Foucault also observed is the only object in the painting that has no function other than to be seen, it reminds us that our differences are negligible. As Shaun concludes, we are also animals fighting for survival.

In 16 orbits, the Earth on its tilted axis delivers a succession of landmasses that the astronauts can name but are de-familiarised by distance and momentum. The Pyramids, the New Zealand fjords, and a desert of dunes are “entirely abstract [and] … could just as easily be a closeup of one of the heart cells they have in their Petri dishes”. Japanese astronaut Chie’s laboratory mice – the canaries in the coal mine of their endeavour – finally learn to negotiate micro gravity “rounding their shoebox module like little flying carpets”. And, on a spacewalk, British astronaut Nell looks back at the “vast spread of the space station and, in this moment it, not earth, feels like home”.

This disassociation from the planet is common among returned astronauts who often report a feeling of closer affinity with their spacecraft. Harvey’s evocative prose describes the tension between a longing for the planet they think of as “mother” and the ambition to leave home forever. At one point Shaun wonders why they are trying to go where the universe doesn’t want them when “there’s a perfectly good earth just there that does.” But later he expresses frustration with the necessity to orbit two hundred and fifty miles above the earth. The moon, he reckons, is just the start.

What Harvey’s novel so skilfully exposes is the human cost of space flight set against the urgency of the climate crisis. The future of humanity is written, Shaun tells Pietro, “with the gilded pens of billionaires”. So while an unprecedented weather event threatens life below, the six astronauts and cosmonauts are rigorously documenting “their own selves”, taking “blood, urine, faecal and saliva samples” and monitoring “heart rates and blood pressure and sleep patterns” to satisfy some “grand abstract dream of interplanetary life” away from Earth.

Orbital is a slim volume of 135 pages but the economy of Harvey’s writing manages to convey a whole universe of meaning. She taps the contemporary zeitgeist of planetary insecurity alongside the span of history from Las Meninas to the spectacle of astronauts “imagineered, branded and ready”, prepared for consumption by “Hollywood and sci-fi, Space Odyssey and Disney.” “They’re humans,” writes Harvey, “with a godly view that’s the blessing and also the curse.”

Hollywood aside, I was reminded more of John Carpenter’s budget film Dark Star where bored astronauts on an interminable mission to destroy unstable planets are fixated on their dwindling supply of toilet paper. There is a sense, in Orbital, that the mundanity of decay is already overwhelming the spectacle of orbit. The module is “old and creaky” and “a crack has appeared”. The International Space Station is, after all, due to be decommissioned in 2031. Harvey has written a novel for the end of the world as we know it. The hope it offers is that we might learn to know the earth differently, while we can.

Debra Benita Shaw, Debra Benita Shaw is Reader in Cultural Theory in the School of Architecture and Visual Arts, University of East London

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Growing up in a Pakistani village in the 2000s, sustainability was embedded throughout my daily life. My family has always been cautious of wasting energy, gas or water because these resources are expensive. We grew most of our own vegetables and reared poultry for eggs. By just buying a few essential groceries from the nearby market, we produced very little household waste. Food scraps were fed to our cattle, and we’d save any plastic bags to reuse.

But now, living in Ireland, I feel anxious about society’s increasing plastic footprint and level of overconsumption.

The United Nations defines sustainability as “meeting the needs of the present without compromising the ability of future generations to meet their own needs.”. But so much complicated jargon makes it difficult to distinguish between environmentally ethical practices and mere feelgood marketing.

Some major brands and big corporations promote and package their products as more eco-friendly than they actually are. In 1986, American environmentalist Jay Westerveld coined the term “greenwash” to describe hotels that were promoting towel reuse as an environmentally conscious initiative, when it was really a cost-cutting measure.

Today, greenwashing encompasses a wide range of deceptive marketing tactics, but as consumers, we have the right to know the true environmental impact of our choices. Here are four ways to avoid being duped by greenwash:

1. Look for marketing buzzwords

Look out for feelgood marketing and buzzwords such as “natural”, “eco-friendly”, “sustainable” and “green”. These labels can be open-ended, without a technical definition or any legal requirements. For example, the term “compostable” differs from “home compostable” – it requires industrial processing with high temperatures, even though it may sound eco-friendly.

There’s no legal time limit for calling something degradable – everything breaks up eventually, even plastic bags.

There is no such thing as a totally carbon-free product. Every process, every product, every supply chain has carbon emissions associated with it. So any marketing language should mirror the impact of that particular product or brand.

Some brands use cute-looking emojis and caricatures with buzzwords that look similar to some certifications, but in reality, they are meaningless. To address this, the European Commission recently proposed a directive, requiring companies to back up green claims with evidence, focusing on life-cycle and environmental footprint methods, setting minimum requirements for sustainability labels and logos.

2. Verify any claims

Pause before you purchase anything and demand evidence to back up any claims that a brand makes.

Either look for statistics that prove the claims on a company’s website, third-party certification or ask the brand and supplier for the evidence of their claims. If they are truly eco-conscious, they’ll proudly share the real numbers.

3. Look for certification

Legit third-party certifications like the EU-mandated energy labels provide valuable and true information about the energy efficiency of household electric appliances. Don’t fall for random stickers that give the impression of formal validation but don’t require any specific criteria to be met.

Plastic recycling labels can be confusing too. The triangle with three chasing arrows, called the Mobius Loop is a universal symbol that means “recyclable”. But, the Mobius Loop with a number in it indicates the type of plastic (there are seven different types) – not that the packaging is recyclable.

Even if technically recyclable, plastic needs to be dry, clean and separated before being recycled. One plastic water bottle may contain three or four different types of plastics, from the bottle itself to the cap and label. Together as a composite, some can be difficult to recycle.

Tthe new tethered bottle caps are mandated by the EU to prevent litter, but they still don’t make recycling any easier.

4. Take a big picture view

Some companies genuinely care. For 35 years, outdoor clothing company Patagonia has pledged 1% of sales to conservation. More than US$89 million (£69 million) has been donated to environmental groups globally through its 1% for the Planet initiative. Cosmetics retailer Lush is working hard to close the loop by limiting water consumption and preventing as much packaging waste as possible.

Investigate the brand’s overall effort to be transparent and environmentally friendly, rather than just looking at one product. If companies aren’t setting clear targets, sharing their progress and being open with their customers, switch to brands that do provide the evidence, listen to their customers and respond.

As paying customers, we have a right to know the environmental footprint of the products and services we’re buying.

Don’t have time to read about climate change as much as you’d like?
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Lala Rukh, Doctoral Researcher in Energy, University of Galway

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Is it possible to heat the planet to dangerous levels and then cool it down later? Economic models charting the world’s path to net zero emissions say yes.

Theoretically, the cheapest way to global decarbonisation is to delay cutting emissions to reach net zero and assume it will be possible to remove huge volumes of CO₂ from the atmosphere later. As the annual UN climate conference kicks off in Azerbaijan, hopes of sticking to the 1.5°C target, while continuing to expand fossil fuel production, are based on this assumption.

However, this bet on future large-scale carbon removal risks becoming a “get out of jail free” clause that allows high emissions to continue inflaming the climate crisis.

A new study by leading scientists has criticised the overconfidence of policymakers and climate modellers – even the authors of the 2015 Paris agreement – for making this gamble. Their research highlights the pitfalls of assuming temperature thresholds can be safely exceeded and then reinstated.

They’re right – and the problem runs even deeper. The challenge of implementing carbon removal at the scale required isn’t simply a matter of the technology being available and cost effective to deploy. Large-scale CO₂ removal depends on there being vast amounts of land to store carbon in trees and soil.

Credible and sustainable limits

The sheer space needed for schemes like tree planting and bioenergy with carbon capture and storage (burning biomass, capturing the carbon and storing it underground) would demand a transformation of how we use and manage land that may be almost impossible to deliver. And if it were actually deployed, it would further traverse other planetary boundaries, with potentially irreversible consequences.

If scientific modelling of the path to net zero emissions fails to account for these obstacles, policymakers could receive flawed advice.

In articles we published recently in the academic journals Nature Communications, Science and One Earth, we proposed how to reframe the role of carbon removal in reaching net zero emissions. A more sober assessment of carbon removal’s real-world potential will help realise its contribution to keeping global temperatures down, and refocus attention on the primary task of cutting emissions: phasing out fossil fuels.

Changing how people use land looks feasible on paper, but it often falls apart in the real world because of a complex web of social, cultural, environmental and political factors unique to each region.

Think about British sheep farmers. Their operations might not be highly profitable or climate friendly, but farming is their identity and heritage. Cold rationality says we should turn that land into forests, but culture and politics say that’s impossible.

In Brazil, soybean farmers often accrue significant debt and enter exclusive contracts with multinational seed producers, legally binding them to certain farming practices. Their use of land isn’t just a job, it’s often a trap of inescapable legal and financial commitments.

Setting aside vast territory to whisk away carbon would force major trade-offs and leave governments relying on the fantasy of perfectly balanced trade to feed their populations. In reality, governments will always put a plentiful food supply first. India’s 2023 ban on rice exports after a poor harvest shows how food security influences government decisions.

Changing how people use land to produce food, timber and fibre for clothes at the scale needed to lower temperatures means working with tens of millions of small family farms. Or it implies horrific human rights abuses if their consent is overridden.

These hurdles are systemic challenges to land-based carbon removal – and hence, of scenarios that assume overshooting and then returning below 1.5ºC of global warming.

Don’t forget ecology

Take California, where the state government experimented with rolling out a forest-based carbon removal project. This was found to be among the cheapest forms of land-based removal in the most recent IPCC report. The project included an additional risk pool of extra trees to mitigate against fire consuming the carbon the forest had removed.

The pool was intended to last a century, but burned down after ten years. The implication? Carbon removal in California will need to gobble up even more land than planned.

These examples tell us that we haven’t accepted the reality of mitigating climate change using land. Compare this with renewable energy. Researchers have a sophisticated understanding of challenges like the intermittency of energy generation from solar panels and wind turbines that can engender solutions like battery storage. As a result, clearer routes exist for scaling up renewables than for sustainable carbon removal.

A plan for global carbon removal will need to take social and political systems seriously. It also needs to factor in ecological limits – what evidence suggests ecosystems can tolerate without collapsing. This implies we should prioritise (at sustainable scales) carbon removal that also boosts biodiversity, such as restoring degraded forests, which sequester much more carbon than single-species plantations and are more resilient to increasing climate hazards like fires.

Durable, nature-positive schemes will require engaging and consulting with local communities, rather than top-down identikit solutions. This takes time.

Changing the way people use millions of hectares of land can’t be done on a spreadsheet. It requires policymakers to engage with the rich and messy reality of the way humans live on it. The patchwork of failed carbon removal schemes around the world suggests that doing this is much harder than is currently understood.

Both science and politics need to take account of this, and fast.

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O.l. Perkins, Research Associate, King's College London; Alexandra Deprez, Research Fellow, International Climate Governance, Iddri, Sciences Po , and Kate Dooley, Research Fellow, School of Geography, Earth and Atmospheric Sciences, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Carbon offsets have become big business as more companies make promises to protect the climate but can’t meet the goals on their own.

When a company buys carbon offsets, it pays a project elsewhere to reduce greenhouse gas emissions on its behalf – by planting trees, for example, or generating renewable energy. The idea is that reducing greenhouse gas emissions anywhere pays off for the global climate.

But not all offsets have the same value. There is growing skepticism about many of the offsets sold on voluntary carbon markets. In contrast to compliance markets, where companies buy and sell a limited number of allowances that are issued by regulators, these voluntary carbon markets have few rules that can be enforced consistently. Investigations have found that many voluntary offset projects, forest management projects in particular, have done little to benefit the climate despite their claims.

I specialize in sustainable finance and corporate governance. My colleagues and I recently conducted the first systematic, evidence-based look at the global landscape of voluntary carbon offsets used by hundreds of large, publicly listed firms around the world.

The results raise questions about how some companies use these offsets and cast doubt on how effective voluntary carbon markets – at least in their current state – are in assisting a global transition to net-zero-emissions.

Which companies use low-quality offsets might surprise you

Our analysis shows that the global carbon-offset market has grown to comprise a rich variety of offset projects. Some generate renewable energy, contribute to energy-efficient housing and appliances, or capture and store carbon. Others preserve forests and grassland. The majority are based in Asia, Africa and the Americas, but they exist in other regions too.

Companies use these projects to boost their environmental claims in order to help attract investors, customers and support from various groups. That practice has skyrocketed, from virtually nothing in 2005 to roughly 30 million metric tons of carbon offset per year in 2022. Investment banking firm Morgan Stanley in 2023 forecast that the voluntary offset market would grow to about US$100 billion by 2030 and to around $250 billion by 2050.

For our analysis, we examined 866 publicly traded companies that used offsets between 2005 and 2021.

We found that large firms with a high percentage of big institutional investors and commitments to reach net-zero emissions are particularly active in voluntary carbon markets.

Our results also reveal a peculiar pattern: Industries with relatively low emissions, such as services and financial industries, are much more intensive in their use of offsets. Some used offsets for almost all of the emissions cuts they claimed.

In contrast, high-emissions industries, such as oil and gas, utilities or transportation, used negligible amounts of offsets compared to their heavy carbon footprints.

These facts cast a cloud of doubt on how effective voluntary carbon markets could really be at cutting global greenhouse gas emissions. They also raise questions about companies’ motives for using offsets.

Why companies rely on offsets: 2 explanations

One explanation for these patterns is that offsetting is a means to “outsource” efforts to transition away from greenhouse gas emissions. Companies with smaller carbon footprints find it cheaper to buy offsets than to make expensive investments in reducing their own emissions.

At the same time, we found that emissions-heavy companies were more likely to reduce their own emissions in-house, because offsetting massive amounts of emissions every year for an indefinite future would be more costly.

A more pernicious explanation for the growth in voluntary offsets is that offsets enable “greenwashing.” In this view, companies use offsets to cheaply refurbish their image to naive stakeholders who are not well informed about the quality of offsets. Agencies rate offset projects on how likely they are to meet their climate claims, among other indicators of the trustworthiness of offsets. Our reviews of pricing data and ratings found that projects rated as low quality have substantially lower prices.

We found that relatively few of the 1,413 offset projects used by companies in our sample had been verified as high quality by an external carbon rating agency. Most offset credits used by companies were strikingly cheap. More than 70% of retired offsets were priced below $4 per ton.

These explanations are not mutually exclusive. We found that low-emissions companies could easily alter their peer rankings for ESG performance – how well they do on environmental, social and governance issues – by offsetting a small quantity of emissions.

Fixing the voluntary market for the future

Our findings have important implications as policymakers and regulators debate rules for the voluntary carbon markets.

The data suggests that voluntary carbon markets are currently flooded with cheap, low-quality offsets, likely due to a lack of integrity guidelines and regulations for voluntary carbon markets to ensure the transparency and authenticity of offset projects. This lack of guidelines may also encourage the use of low-quality offsets.

Ever since Article 6 of the Paris climate agreement created principles for carbon markets and ways countries could cooperate to reach climate targets, agreeing on how to implement those principles has been a challenge. For the principles to be successful, negotiators must agree on project eligibility and information disclosure standards, among other issues.

In April 2024, SBTi, the world’s leading science-based arbiter of corporate climate targets, added urgency to that process when it announced that it would allow companies to meet their carbon goals with carbon offsets to cover emissions in their supply chains.

The following month, the U.S. Treasury, Energy and Agriculture departments jointly released a policy statement laying out their own template for rules to govern voluntary carbon markets. “Voluntary carbon markets can help unlock the power of private markets to reduce emissions, but that can only happen if we address significant existing challenges,” U.S. Treasury Secretary Janet Yellen said at the time.

Article 6 and standards for carbon offsets are on the agenda for the 2024 United Nations climate conference, COP29, Nov. 11-22 in Baku, Azerbaijan.

With many segments of voluntary carbon markets faltering, the COP29 summit may be a make-or-break moment for voluntary carbon offsets to become a viable contributor to decarbonization going forward.

Sehoon Kim, Assistant Professor of Finance, University of Florida

This article is republished from The Conversation under a Creative Commons license. Read the original article.

For the third year in a row, the United Nations Climate Change Conference will be hosted by an authoritarian state that sells fossil fuels. This week the 29th “conference of the parties”, COP29, is being held in Baku, Azerbaijan. It follows COP28 in Dubai, the United Arab Emirates last year and COP27 in Sharm El-Sheikh, Egypt the year before that.

It’s concerning that a succession of authoritarian and fossil fuel-rich states have been selected to host international climate negotiations. It means we must pay extra attention to political influences on the talks and beware of greenwashing by the hosts.

The domestic politics of these states also shapes global supply chains of fossil fuels and critical minerals. This in turn directly affects Australia’s trade, economy and foreign policies.

There are now more authoritarian and hybrid regimes globally than there are democracies. So some basic understanding of how authoritarian states respond to climate change matters, for Australia and the rest of the world.

What is an authoritarian state and why should we care?

Power in authoritarian states is concentrated in the hands of a single ruler or group of elites. People under authoritarian rule lack many basic human rights, and risk punishment for speaking out against the political regime. Rule of law and political institutions are weak, so abuse of power can go unchecked.

Not all authoritarian states are fossil fuel producers, although many are. Some also supply critical minerals for electric vehicles and renewable energy.

China dominates global critical minerals supply chains and electric vehicle manufacturing.

Russia remains one of the largest fossil fuels producers and exporters, despite sanctions since 2022. It is also using revenues from these exports to continue its war in Ukraine.

Most of the major oil, coal and gas producers in the Middle East and Central and Southeast Asia are non-democracies or hybrid autocracies. UAE lifted oil production after hosting COP28.

Indonesia, considered “partly free”, is the world’s largest coal exporter. Despite having signed the Paris Agreement, the Indonesian government recently approved close to one billion tonnes of coal mining. Domestic coal consumption and export is expected to rise.

What is at stake at COP29?

At COP29, countries are expected to announce stronger national climate commitments. This is essential for limiting global temperature rise to 1.5°C and achieving net-zero emissions by mid-century.

It is hoped more concrete steps will also be taken towards providing financial support to developing countries struggling with the energy transition.

In previous years, authoritarian states have been able to block or undermine progress at international climate negotiations. Expect to see more of this at COP29.

China’s cautious approach to phasing out coal has affected COP negotiations in the past. Even after COP28, where a roadmap to transition away from fossil fuel was agreed, coal remains crucial to China’s economy.

At COP27 in Egypt, Russian energy lobbyists were permitted to attend even after the invasion of Ukraine. They met with heads of states and energy ministers from Africa, Asia and the rest of the world.

Russia will likely use COP29 to promote its own agenda, including its nuclear export industry. Since the war began, Russia has sought to frame Western-led cooperation on climate as a form of neo-colonialism designed to undermine its economy and others like it.

The mere fact COP29 is being held in Azerbaijan may be a consequence of Russian intervention. Russia reportedly opposed COP29 being held in Bulgaria after the European Union condemned the invasion of Ukraine and imposed sanctions.

Climate politics in autocracies

Finally, evidence suggests as climate change intensifies, authoritarianism could gain legitimacy over liberal democratic norms, for several reasons.

First, authoritarian states can provide effective short-term disaster response and relief. The central authorities in these states can mobilise considerable human and material resources without many institutional checks and balances.

Second, authoritarian states can introduce large-scale green energy technologies, such as solar, wind, hydro and nuclear, using substantial government funding. This has happened in China and many other states, including Laos, Vietnam, and Morocco. In doing so, authoritarian states can portray themselves as more capable than democracies.

Finally, following the demise of fossil fuel-related industries, functioning authoritarian states can manage massive job losses and suppress social resentment in ways democratic governments do not.

Challenges lie ahead

Long-standing democracies such as the United States and Australia have been bogged down in the complex politics around climate and energy transition. This has led to scientific evidence being questioned, crackdowns on environmental activism, and restrictions on media freedom. We need to make sure addressing climate change doesn’t undermine democratic principles.

What’s more, authoritarian and fossil fuel rich states have actively funded climate denial in democratic societies. For example, Russia was found to be promoting anti-climate misinformation on social media.

As far as China goes, the global superpower is extending its geopolitical influence by helping developing countries access cheap renewable energy technologies from non-Western sources. This challenges the leading role of the US and the West in the field of international cooperation on climate change.

As COP29 gets underway, the potential for authoritarian states to shape the outcomes remains strong. Understanding how these regimes work, and what they want, is vital as they affect global cooperation on climate change.

Ellie Martus, Senior Lecturer in Public Policy, School of Government and International Relations, Griffith University and Fengshi Wu, Associate Professor in Political Science and International Relations, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

It’s a big year in America – for wildlife as well as for politics. I’m talking about periodical cicadas.

These curious creatures spend most of their lives in the ground, emerging after 13 or 17 years to eat, breed, die and repeat the cycle. For the first time in more than 200 years, two specific broods of the 13- and 17-year cicadas have emerged together: Brood XIX, in the southeastern United States, and Brood XIII, found in the country’s Midwest.

What’s more, this time the emergence of these broods also happens to coincide with an unrelated event on the other side of the world: the emergence of a big batch of Australian greengrocer cicadas, which have a seven-year life cycle.

This remarkable event has been 1,547 years in the making. Thinking about it sheds light on some of the deepest questions about mathematics.

Did we invent mathematics, or was it there all along?

Are mathematical facts created or discovered? Ask a mathematician, and they are likely to tell you that mathematical facts are discovered.

But this is perplexing: if such facts are discovered, what are we discovering? Are mathematical facts somehow “out there” before we discover them? Does that mean there’s some realm of pure mathematics that we uncover with our minds?

These sorts of questions quickly begin to feel pretty uncomfortable. We find ourselves in deep metaphysical territory, beset by questions about the nature of reality.

For it seems that in addition to the physical components of the world, there must also exist things like numbers, and even more exotic mathematical entities such as sets and functions. These seem to be real objects, that we gradually uncover through the activity of mathematics.

On the other hand, if we think of mathematics as an act of creation, these metaphysical questions disappear. Mathematics can be like a language we’ve invented to describe the world.

In this picture, mathematics is just a very precise way of speaking that happens to be useful.

Which brings us back to the cicadas: these little critters put pressure on the idea that mathematics is something we created ourselves.

Cicada life cycles

North American cicadas have life cycles that last for prime numbers of years. Why 13 or 17 years? Why not 12, 14, 15 or 16?

One explanation asks us to imagine the cicadas are hunted by periodical predators that spend most of their lives in the ground and then, after a period of time, emerge to hunt. In particular, suppose there are five species of predator, with life cycles of two, three, four, five, six and seven years.

A cicada will have the best chance of survival if it can emerge from the ground when its predators are lying dormant. The cicadas with the best chance of survival will therefore be those that manage to avoid emerging at the same time as their predators.

It turns out the best way to avoid periodical predators is to move to a life cycle that lasts a prime number of years.

To see this, suppose a cicada has 12-year life cycle. Whenever it comes out of the ground, there will be predators with two-, three-, four- and six-year life cycles on the hunt.

A cicada with a 14-year life cycle will overlap with predators possessing two- and seven-year life cycles, and a cicada with a 15-year life cycle will overlap with predators on three- and five-year cycles. Cicadas with 13- or 17-year life cycles, by contrast, will generally avoid all of these predators.

There is a general mathematical result that explains all of this, involving the lowest common multiple of two numbers: the smallest number that both can divide into evenly.

How often a cicada overlaps with a predator turns out to depend on the lowest common multiple of the cicada and predator life-cycles. For instance, a cicada with a 12-year life cycle and a predator with a two-year life cycle will overlap every 12 years, which is the lowest common multiple of two and 12. By contrast, a cicada with a 13-year life cycle and a predator with a 2-year life cycle will only overlap every 26 years.

As a general rule, having a prime-numbered life cycle is a very good way for a cicada to ensure it overlaps as little as possible with its predator.

Another theory suggests the prime-numbered life cycles actually help cicadas avoid interbreeding with other broods. Either way, similar mathematical logic applies.

This is also why Australian cicadas (with their seven-year cycle) overlap so infrequently with their US cousins (with 13- and 17-year cycles). The lowest common multiple of seven, 13 and 17 is 1,547!

What happens when mathematics explains biology?

As the US philosopher Alan Baker has argued, this biological explanation for why cicadas have prime-numbered life cycles relies heavily on mathematics. In this case, it seems like facts about mathematics explain facts about biology and evolution.

This is very hard to understand if mathematics is something we have simply created. If mathematics is a language we invented, why should it apparently guide the evolutionary history of cicadas? This would be a bit like saying the planets move the way they do because of how we talk about them in English.

Once we start looking for these explanations involving mathematics, they seem to be everywhere. To take an example from my own research: why do gears in machinery generally have prime numbers of teeth?

The answer is very similar to the cicada story. If gears have a prime-numbered amount of teeth, then the same two teeth will contact each other much less frequently than if the gear-teeth are not prime-numbered.

This ensures that if there is an imperfection on a specific pair of teeth, one from each gear, then the imperfections won’t keep striking each other. This way, the chance of the gear failing is minimised.

The end of an empire

One thousand, five hundred and forty-seven years is a long time – long enough to see empires rise and fall.

Indeed, the last time American and Australian cicadas emerged together, in the year 477, the Western Roman Empire was in the throes of collapse.

It is, of course, a coincidence that they have emerged again at what may be another turning point in Western civilisation. One can’t help but wonder, though: are the bugs to blame?

Sam Baron, Associate Professor, Philosophy of Science, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.