The science of attribution of major weather events to climate change has come on leaps and bounds in recent years. Instead of always having to say “we can’t attribute this particular storm, drought, or flood to climate change, but it is exactly the kind of thing that is predicted…”, scientists can be much clearer that climate change is responsible. The World Weather Attribution project does exactly this, for instance, saying quite clearly that record high temperatures in April in South East Asia were largely driven by climate change.

A very interesting development in this field is to link the emissions of oil companies to historical wildfires in North America. This spring the Canadian state of Alberta has seen 520 fires burning more than a million hectares of forest, a record for this early in the wildfire season. More fires, and new records, are expected through the summer and to the end of the fire season in October.

More generally, there have been several decades of increasing wildfires in the western United States and southwestern Canada. The average area of wildfires, the number of large fires, the length of the fire season, and the altitude that fires extend to have all increased, as climate change has driven temperatures up and humidity down.

Now a new study has looked at how much the availability of moisture in the atmosphere has declined over the period between 1901 and 2021. This reduction in water content means a greater likelihood that wood will ignite and more chance that fire will spread once it does.

The clever bit is that they have been able to estimate how much of this change is due to companies. Their conclusion is that around half the change in water availability from 1901 to 2021 was caused by the climate pollution attributed to 88 major fossil fuel producers and cement manufacturers. Thirty-seven per cent of the increase in the area burnt over a shorter period, 1986 to 2021, was due to these companies. And they also find that these companies are responsible for half the total global warming observed between 1900 and 2015.

Nearly $4 billion are spent fighting these fires every year, firefighters risk their lives and sometimes die, local people are killed, property and businesses are destroyed and wildlife is massacred. Another new study puts the cost of death and illness from air pollution from US wildfires at $7bn a year, predicting this will rise to $36bn by 2090. The insurance costs are massive, with just the 2018 fires in California destroying more than 22,000 structures and racking up a bill of $140bn.

This is not the first study to link the products of the fossil fuel industry directly to real-world impacts, but it’s perhaps the most interesting because it highlights the very real costs to society occurring in one of the world’s most litigious places. If a third of the cost of hundreds of billions of damage is caused by identifiable companies, surely it will not be long before states, companies and individuals add the cost of wildfires to the roll of climate change lawsuits stacking up against Big Oil.

Dr Richard Dixon is an environmental campaigner and consultant

Climate change: Prospect of legal action rises after 88 major fossil fuel producers blamed for half of all global warming – Dr Richard Dixon