Attribution of the Influence of Human‐Induced Climate Change on an Extreme Fire Season

A record 1.2 million ha burned in British Columbia, Canada's extreme wildfire season of 2017. Key factors in this unprecedented event were the extreme warm and dry conditions that prevailed at the time, which are also reflected in extreme fire weather and behavior metrics. Using an event attribution method and a large ensemble of regional climate model simulations, we show that the risk factors affecting the event, and the area burned itself, were made substantially greater by anthropogenic climate change. We show over 95% of the probability for the observed maximum temperature anomalies is due to anthropogenic factors, that the event's high fire weather/behavior metrics were made 2–4 times more likely, and that anthropogenic climate change increased the area burned by a factor of 7–11. This profound influence of climate change on forest fire extremes in British Columbia, which is likely reflected in other regions and expected to intensify in the future, will require increasing attention in forest management, public health, and infrastructure. Plain Language Summary A record 1.2 million ha burned in British Columbia, Canada's extreme wildfire season of 2017. Key factors in this unprecedented event were the extreme warm and dry conditions that prevailed at the time, which are also reflected in extreme fire weather and behavior metrics. To quantify the influence of human‐induced climate change on this event, we compare the likelihood of the risk factors affecting the extreme fire season to an estimate of what the likelihood might have been without the human component. We find that human‐induced climate change contributed greatly to the probability of the observed extreme warm temperatures, high wildfire risk, and large burned areas. Key Points An event attribution analysis is performed for the record‐breaking wildfire season of 2017 in BC Anthropogenic climate change greatly increased the likelihood of extreme warm temperatures and high fire risk A strong anthropogenic climate change contribution is also found for the large area burned