Climate Change and increasing wildfires worldwide

The climate crisis is fuelling extreme fires across the planet

Hamish Clarke, The University of Melbourne

We’ve all seen the alarming images. Smoke belching from the thick forests of the Amazon. Spanish firefighters battling flames across farmland. Blackened celebrity homes in Los Angeles and smoked out regional towns in Australia.

If you felt like wildfires and their impacts were more extreme in the past year – you’re right. Our new report, a collaboration between scientists across continents, shows climate change supercharged the world’s wildfires in unpredictable and devastating ways.

Human-caused climate change increased the area burned by wildfires, called bushfires in Australia, by a magnitude of 30 in some regions in the world. Our snapshot offers important new evidence of how climate change is increasing the frequency and severity of extreme fires. And it serves as a stark reminder of the urgent need to rapidly cut greenhouse gas emissions.

The evidence is clear – climate change is making fires worse.

A view of the Palisades fire zone in Los Angeles, where climate change fuelled the fires in January. Allen J. Schaben/Getty

Clear pattern

Our study used satellite observations and advanced modelling to find and investigate the causes of wildfires in the past year. The research team considered the role that climate and land use change played, and found a clear interrelationship between climate and extreme events.

Regional experts provided local input to capture events and impacts that satellites did not pick up. For Oceania, this role was played by Dr Sarah Harris from the Country Fire Authority and myself.

In the past year, a land area larger than India – about 3.7 million square kilometres – was burnt globally. More than 100 million people were affected by these fires, and US$215 billion worth of homes and infrastructure were at risk.

Not only does the heating climate mean more dangerous, fire-prone conditions, but it also affects how vegetation grows and dries out, creating fuel for fires to spread.

In Australia, bushfires did not reach the overall extent or impact of previous seasons, such as the Black Summer bushfires of 2019–20. Nonetheless, more than 1,000 large fires burned around 470,000 hectares in Western Australia, and more than 5 million hectares burned in central Australia. In Victoria, the Grampians National Park saw two-thirds of its area burned.

In the United States, our analysis showed the deadly Los Angeles wildfires in January were twice as likely and burned an area 25 times bigger than they would have in a world without global warming. Unusually wet weather in Los Angeles in the preceding 30 months contributed to strong vegetation growth and laid the foundations for wildfires during an unusually hot and dry January.

In South America, fires in the Pantanal-Chiquitano region, which straddles the border between Brazil, Bolivia and Paraguay, were 35 times larger due to climate change. Record-breaking fires ravaged parts of the Amazon and Congo, releasing billions of tonnes of carbon dioxide.

Protestors march for climate justice and against wild fires affecting the entire country in Sao Paulo, Brazil. Faga Almeida/Getty

Not too late

It’s clear that if global greenhouse gas emissions continue to rise, more severe heatwaves and droughts will make landscape fires more frequent and intense worldwide.

But it’s not too late to act. We need stronger and faster climate action to cut fossil fuel emissions, protect nature and reduce land clearing.

And we can get better at responding to the risk of fires, from nuanced forest management to preparing households and short and long-term disaster recovery.

There are regional differences in fires, and so the response also need to be local. We should prioritise local and regional knowledge, and First Nations knowledge, in responding to bushfire.

Action at COP30

Fires emitted more than 8 billion tonnes of carbon dioxide in 2024–25, about 10% above the average since 2003. Emissions were more than triple the global average in South American dry forests and wetlands, and double the average in Canadian boreal forests. That’s a deeply concerning amount of greenhouse pollution. The excess emissions alone exceeded the national fossil fuel CO₂ emissions of more than 200 individual countries in 2024.

Next month, world leaders, scientists, non-governmental organisations and civil society will head to Belem in Brazil for the United Nations annual climate summit (COP30) to talk about how to tackle climate change.

The single most powerful contribution developed nations can make to avoid the worst impacts of extreme wildfires is to commit to rapidly cutting greenhouse gas emissions this decade.

Hamish Clarke, Senior Research Fellow, The University of Melbourne

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

Climate change - when rainforests are no longer carbon sinks - the Australian example

A crucial store of carbon in Australia’s tropical forests has switched from carbon sink to carbon source

Hannah Jayne Carle, Australian National University; Adrienne Nicotra, Australian National University; David Bauman, Institut de recherche pour le développement (IRD); Michael N Evans, University of Maryland, and Patrick Meir, Australian National University; University of Edinburgh

One approach to help fight climate change is to protect natural forests, as they absorb some atmospheric carbon released by burning fossil fuels and store large volumes of carbon.

Our new research on Australia’s tropical rainforests challenges the assumption that they will keep absorbing more carbon than they release.

We found that as climate change has intensified over the past half-century, less and less carbon has been taken up and converted to wood in the stems and branches of the trees in these forests. Woody biomass is a large and relatively stable store of carbon in forests, and acts as an important indicator of overall forest health.

The effect has been so pronounced that the woody biomass of these forests has gone from being a carbon sink to a carbon source. This means carbon is being lost to the atmosphere due to trees dying faster than it is being replaced by tree growth.

This is the first time woody biomass in tropical forests has been shown to switch from sink to source. Our research indicates the shift likely happened about 25 years ago.

It remains to be seen whether Australian tropical forests are a harbinger for other tropical forests globally.

What did we find?

Since 1971, scientists have tracked around 11,000 trees in 20 tracts of tropical rainforest in Australia’s far northeast, now part of the Queensland Permanent Rainforest Plots Network. This 49-year research effort is one of the world’s longest and most comprehensive of its kind.

We analysed this long-term data and found a clear signal: woody biomass switched from being a carbon sink to a carbon source about 25 years ago.

Why? One reason: trees are dying twice as fast as they used to.

Tropical rainforest tree species are adapted to generally warm, wet conditions. As the climate changes, they are subjected to increasingly extreme temperatures and drier conditions.These kinds of extreme climate events can damage wood and leaves, limiting future growth and leading to higher rates of tree death.

We also found tree deaths from cyclones reduced how much carbon these forests could absorb. Cyclones in far north Queensland are projected to become increasingly severe under climate change. They are also likely to push further south, potentially affecting new areas of forest.

Isn’t carbon dioxide plant food?

Burning fossil fuels and other human activities have increased carbon dioxide levels in the atmosphere. This should make it easier for plants to absorb CO₂ from the air, photosynthesise and grow. Given this, Earth system models predict higher atmospheric CO₂ levels will stimulate plant growth and increase how much carbon tropical forests can take up.

Also, remote sensing shows the canopies of tropical forests on Australia’s east coast are about 20% greener than they were in the 1980s. This suggests forest canopy growth has increased due to higher levels of CO₂ in the atmosphere. But this isn’t the whole picture.

Our data shows any potential increase in photosynthesis resulting in greener forest canopies has not translated to greater carbon storage in stems and branches.

The reason may be that tree growth can be limited by water, nutrients and heat. Our work suggest that warmer and drier conditions have limited tree growth even as CO₂ concentration has increased.

In a separate study, scientists artificially increased CO₂ and found the extra carbon taken up by leaves wasn’t being stored as extra woody growth. Rather, it was quickly released through roots and soil microbes.

What about other forest carbon stocks?

It will be challenging to find out whether these forests as a whole (including wood, roots, leaves and soils) have declined in carbon sink capacity.

The use of a specialised research tool known as eddy covariance towers could help, as these measure overall CO₂ movement into and out of ecosystems.

As of yet, only 15 years of this kind of data from three tropical Australian sites is available, which currently limits our ability to describe the fuller impact of climate change.

In any case, we know carbon stored in forest canopies and soils is often broken down and released back to the atmosphere faster than carbon in woody biomass.

So while Australia’s tropical rainforest carbon stores remain large, they may be less secure and reliable than in decades past.

Long term datasets are vital

When people visit Australia’s tropical rainforests, they can see intact stretches of biodiverse forest and large, carbon-rich trees. It’s hard to directly see the changes we have detected – for now, they’re only visible in the data.

Without high-quality long-term datasets, this signal would have been almost impossible to detect. Unfortunately, persistent funding shortages for long-term ecological monitoring threaten the continuity of these hugely valuable datasets.

Australia has the potential to assume a globally leading role in tropical ecosystem science. In light of state and national biodiversity and emission reduction commitments, Australian governments should support continued monitoring of vital ecological research sites.

Tropical forests may not be saviours

The fact that woody biomass in Australia’s tropical rainforests is now a net source of carbon has major implications.

These findings challenge our future reliance on forests as natural absorbers of extra atmospheric carbon.

We don’t know yet whether all tropical forests will respond similarly. Evidence on carbon sink capacity is mixed. Rainforests in South America are showing a decline while African rainforests are generally not.

Overall, the world’s tropical forests remain very significant stores of carbon and biodiversity. Their protection remains essential despite the climate risks they face.

Hannah Jayne Carle, Postdoctoral Researcher in Tropical Forest Ecology, Hawkesbury Institute for the Environment, WSU, Australian National University; Adrienne Nicotra, Professor of Ecology and Evolution, Research School of Biology, the Australian National University, Australian National University; David Bauman, Research Scientist in Plant Ecology, Institut de recherche pour le développement (IRD); Michael N Evans, Professor in Earths Systems Science, University of Maryland, and Patrick Meir, Honorary Professor of Forest Ecosystems, Australian National University; University of Edinburgh

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

Climate change - sea levels will rise even if the global temperature increase is only 1.5°C

                          Daytona, Florida, United States                  Shutterstock

With all the focus and debate on the target of limiting the temperature increase on the planet to 1.5°C pre-industrial levels, a very real concern is often overlooked. That concern is the impact of the temperature increase that has already happened. The reality is that even if the target of limiting the  increase to 1.5°C was achieved, ocean levels will still rise and at a rate much faster than previously predicted. Scientists at Durham University in the UK have reviewed three lines of evidence on the current situation: satellite observations of ice loss and sea level rise over the past three decades; studies of warm periods in the past; and computer models of ice sheets.

The conclusion was startling. The Greenland and West Antarctica ice sheets are already melting, decades earlier forecast in the last report of the Intergovernmental Panel and Climate Change (IPCC). The melting of the ice sheets is also accelerating. As the scientists at Durham concluded, every fraction of a degree of temperature increase really matters for ice sheets. To merely slow down but not stop the ice sheets melting, the global temrperature increase would need to be reduced to 1°C above the pre-industrial baseline.

In 2024, the average temperature increase world-wide was 1.51°C which makes a mockery of the desired target as it has already been surpassed. The world is on course with current trends to reach a 2.9°C increase in temperature by the end of the century.

The research article can be found at this link: Ice loss at 1.5C 

Health - using a smartphone on the toilet raises the risk of haemorrhoids

                                                                                                Shutterstock

Smartphones have become as ubiquitious in modern life as wearing footwear, so much so that unintended risks of their endless use are often entirely overlooked. It may surprise quite a few people to discover that research by Beth Israel Deaconess Medical Centre in Boston, Massachusetts, USA has found that the use of smartphones on the toilet is associated with a 46 % greater risk of developing haemorrhoids. While there has been anecdotal evidence of the risk of recent years, little to no research has been done on this subject.

The current research was based on a study using questionnaires provided to 125 people who were about to undergo colonoscopies. Two-thirds of the participants, who were all aged over 45 years, stated they used smartphones on the toilet and 37 % of them spent more than 5 minutes on the toilet as a result compared to just 7 % whom did not use a smartphone.

What is the suggested reason for developing haemorrhoids ? It's speculated that people's pelvic floor muscles have less support in the toilet sitting position than when sitting on a flat surface such as a chair. As a result there is an increase in passive pressure engorging the haemorrhoid cushion in that region of the body.  

The research article can be accessed at this link: Use of smartphones 

Health - men's brains shrink more rapidly with ageing

                                                                                                   Shutterstock

 
One of the more unusual studies into ageing that has been published this month, has demonstrated that men experience a greater reduction in brain volume across more regions as they age than women do. The longitudinal study released in the Proceedings of the National Academy of Sciences examined 12,500 magnetic resonance imaging (MRI) scans taken from 4,726 people (with at least 2 scans per person taken on an average of 3 years apart). The study participants did not have Alzheimer's disease or any cognitive impairments and were control participants in 14 larger data sets.

The researchers compared the brain structures of individuals over time such as the thickness of grey matter and the size of the hippocampus (which is essential to memory). The results found a greater reduction in volume across more regions in the brains of men than for women.  As one example, the postcentral cortex region (responsible for processing sensations of touch, pain, temperature and the body's own movements and position) declined by  2.0% per year in men and only 1.2% in women over the same period. 

The results of the study, not surprisingly, led  researchers to conclude that men age faster than women and have a shorter life expectancy. This is hardly new information. A question that remains unanswered by this study is why women are twice as likely to be diagnosed with Alzheimer's disease than men given their brains age more slowly. 

For men, this study only assists with the impression that as they age, they become old codgers.