Has climate change affected California's wildfire season?
In 2018, the California wildfire season was more destructive than any previous California wildfire season on record. Throughout late summer and autumn a series of wildfires broke out across the state with the most severe consequences occuring in Northern California. The most dangerous fire, known as the Camp Fire, killed over 80 civilians.
Experts have drawn links between this year’s extreme wildfire season and increasing global temperatures, but it is difficult to pinpoint exactly how climate change has affected the California wildfires.
The dry vegetation and drought-like conditions over summer offered signs that the fire season would be at least as devastating at the year before, but looking back further, wildfire intensity has been increasing in frequency and intensity over the last decade and fifteen of the largest wildfires in California’s history have taken place this century.
Ioana Colfescu, Research Scientist at the National Centre for Atmospheric Science, has outlined three factors affecting the California wildfires and says that climate change must be considered.
Wildfires in California have been increasing in intensity over the last decade. In 2016, a study published in Proceedings of the National Academy of Sciences found that human-caused climate change was a significant factor in increasing fuel dryness since 1970, and has doubled the cumulative forest fire area since 1984.
Scientists have also shown that rising global temperatures are linked to the earlier onset of Spring. This causes snow and ice to melt earlier in the year, and provides land with more time to dry out over the warmer summer months.
One further factor is the frequency of lightning strikes, which may be increased by climate change, and can be responsible for igniting fires.
Long droughts occur naturally in California, often spanning several years, and wildfires are a natural part of the regional ecology. It can be difficult to detect the local-scale effects of climate change because detailed observational records are relatively short-term. This makes it hard to confidently attribute the cause of any one event.
California has a population of nearly 40 million people, and large numbers of citizens live within forest areas that are at risk of fire. As the regional population continues to rise and more people move to woodland areas, the risk of people encountering wildfires has significantly increased.
Although it is difficult to attribute regional climate or weather events to a specific cause, it is impossible to talk about California’s wildfire season without considering the role of climate change. Climate change is increasing the frequency of extreme weather, and must be considered when looking at regional, individual events.