Human-induced climate change promotes the conditions on which wildfires depend, increasing their likelihood – according to a review of research on global climate change and wildfire risk.
In light of the Australian fires, scientists from the University of East Anglia (UEA), Met Office Hadley Centre, University of Exeter, Imperial College London, and CSIRO Oceans and Atmosphere, have conducted a Rapid Response Review of 57 peer-reviewed papers published since the IPCC’s Fifth Assessment Report in 2013.
All the studies show links between climate change and increased frequency or severity of fire weather – periods with a high fire risk due to a combination of high temperatures, low humidity, low rainfall and often high winds – though some note anomalies in a few regions.
The Rapid Response Review is published as NASA reveals the smoke from Australia’s wildfires will make a “full circuit” around the world.
The fires in Australia are not just causing devastation locally. “The unprecedented conditions that include searing heat combined with historic dryness, have led to the formation of an unusually large number of pyrocumulonimbus (pyrCbs) events”, NASA said in a statement. PyroCbs are essentially fire-induced thunderstorms. They are triggered by the uplift of ash, smoke, and burning material via super-heated updrafts. As these materials cool, clouds are formed that behave like traditional thunderstorms but without the accompanying precipitation.
PyroCb events provide a pathway for smoke to reach the stratosphere more than 10 miles (16 km) in altitude. Once in the stratosphere, the smoke can travel thousands of miles from its source, affecting atmospheric conditions globally.
NASA is tracking the movement of smoke from the Australian fires lofted, via pyroCbs events, more than 9.3 miles (15 kilometers) high. The smoke is already having a dramatic impact on New Zealand, causing severe air quality issues across the county and visibly darkening mountaintop snow.
Beyond New Zealand, by January 8, the smoke had travelled halfway around Earth, crossing South America, turning the skies hazy and causing colorful sunrises and sunsets. The smoke is expected to make at least one full circuit around the globe, returning once again to the skies over Australia.
Rising global temperatures, more frequent heatwaves and associated droughts in some regions increase the likelihood of wildfires by stimulating hot and dry conditions, promoting fire weather, which can be used as an overall measure of the impact of climate change on the risk of fires occurring.
The Rapid Response Review says observational data shows that fire weather seasons have lengthened across approximately 25 per cent of the Earth’s vegetated surface, resulting in about a 20 per cent increase in global mean length of the fire weather season.
The literature review was carried out using the new ScienceBrief.org online platform, set up by UEA and the Tyndall Centre for Climate Change Research. ScienceBrief is written by scientists and aims to share scientific insights with the world and keep up with science, by making sense of peer-reviewed publications in a rapid and transparent way.
Dr Matthew Jones, Senior Research Associate at UEA’s Tyndall Centre and lead author of the review, said: “Overall, the 57 papers reviewed clearly show human-induced warming has already led to a global increase in the frequency and severity of fire weather, increasing the risks of wildfire.
“This has been seen in many regions, including the western US and Canada, southern Europe, Scandinavia and Amazonia. Human-induced warming is also increasing fire risks in other regions, including Siberia and Australia.
“However, there is also evidence that humans have significant potential to control how this fire risk translates into fire activity, in particular through land management decisions and ignition sources.”
At the global scale, burned area has decreased in recent decades, largely due to clearing of savannahs for agriculture and increased fire suppression. In contrast, burned area has increased in closed-canopy forests, likely in response to the dual pressures of climate change and forest degradation.
Co-author Professor Richard Betts, Head of Climate Impacts Research at the Met Office Hadley Centre and University of Exeter, said: “Fire weather does occur naturally but is becoming more severe and widespread due to climate change. Limiting global warming to well below 2°C would help avoid further increases in the risk of extreme fire weather.”
Professor Colin Prentice, Chair of Biosphere and Climate Impacts and Director of the Leverhulme Centre for Wildfires, Environment and Society, Imperial College London, added: “Wildfires can’t be prevented, and the risks are increasing because of climate change. This makes it urgent to consider ways of reducing the risks to people. Land planning should take the increasing risk in fire weather into account.”
The Rapid Response Review is published on ScienceBrief. The papers used in review can be viewed here. This is the first review to use the ScienceBrief resource, with further work planned on areas related to climate change science and its impacts in the run up to the United Nations Climate Change Conference – COP26 – in November.
Given the evidence pointing to the human impact on climate change, it is perhaps surprising that some countries are failing to introduce urgent policy to ensure humans help, not hinder, the climate change issue. CNN reported on January 11 that the Trump administration has “remained steadfast in pursuit of one of its signature policy goals: the gutting of environmental regulations, which include those aimed at curbing climate change.”
CNN continued, “from changes in early January to curb key parts of a landmark environmental protection law to relaxing restrictions on power plant emissions, Trump has attempted to remove many of the guardrails installed by the Obama and previous administrations that can limit the scope of global warming.”
During a White House event on January 9, President Trump said that he did not believe global warming to be a hoax. He added that he wants clean air and clean water, although both relate more to pollution and climate change rather than directly to global warming. He added that he intends to read a book about climate change. New York Times reporter Lisa Friedman asked which book this might be and later tweeted “White House confirmation” that the book in question is “Donald J. Trump: An Environmental Hero,” by Ed Russo. Russo formerly worked as a consultant for Trump.
Meanwhile, the British government is considering reducing the cost of domestic air travel, via Air Passenger Duty, something environmental groups have described as “reckless” (Friends of the Earcth) and “shocking” (Greenpeace), who would instead prefer to see the government channel investment into the U.K. rail system to provide more affordable, greener methods of travel within Britain.