Air is getting thirstier, increasing the risk of wildfires

As temperatures climb, the air is demanding more water, increasing the risk of major fires across the globe, new research has found.  

Unless urgent action is taken to combat the climate crisis, it’s believed forests will be more likely to dry out and forest fires will occur more often, with major implications for carbon storage and human health.  

‘Without strong climate action, there will be many more days each year – at least 30 – when Earth’s forests cross over into this critical flammability zone,’ said Dr Hamish Clarke from the University of Melbourne FLARE Wildlife Research group. ‘This means we’re likely to see more major fires, with all the risks that come with them. 

‘It is currently estimated that over 330,000 annual deaths globally are attributable to smoke inhalation, a number that could increase notably by the turn of the century, particularly in the most populated areas of east Asia.’  

Examining global climate and fire records in all of the world’s forests over the last 20 years, researchers discovered a strong connection between fire activity and vapour pressure deficit (VPD).  

This is how ‘thirsty’ the atmosphere is, calculated by finding the difference between how much moisture is in the air and how much the air can hold when its saturated. The bigger the difference, the more likely forests are to dry out.  

Crucially, warmer air can hold more water, causing the VPD to increase and fuels to dry out more as the climate crisis continues.  

Scientists measured the maximum daily VPD for every forest fire detected using satellite records and a global climate dataset, encompassing 30 million records.  

They the measured the relationship between the VPD and fire activity and found a strong link in forests across the world, from tropical rainforests to boreal coniferous forests.  

Forest fires are much more likely above a certain threshold of VPD, according to the study, which was found to differ between forest types. The threshold was lower in boreal settings compared to temperate forests, for example.  

Dr Clarke said that all around the world we’re likely to see more of the conditions under which forests dry out and become flammable. 

‘Some of the biggest areas of concern are the Amazon rainforest and other tropical forests, as well as northern hemisphere temperate and boreal forests.’ 

It’s hoped the research will help to develop better fire predictions which could help to fight fires and establish warning systems for those living in at risk areas.  

Photo by Matt Howard