Are Wildfires Getting Worse?

The Mendocino wildfire which decimated four counties in California is the largest ever to be recorded in the state’s history. The blaze was finally contained on the 18^th September, having already consumed 459,000 acres of land, destroyed 280 buildings and claimed one human life. The second biggest wildfire in Californian history was the Thomas inferno, which occurred just last year.

While this is a very small sample upon which to base judgements, there is a clear case to be made that the intensity and frequency of wildfires in California and beyond is becoming more extreme ever year. That viewpoint has been lent extra weight by new research conducted by scientists at the University of California Santa Barbara’s Bren School of Environmental Science and Management.

The ENSO effect

At the heart of the new research are the two meteorological patterns of El Niño and La Niña, which affect the warming and cool of the Pacific Ocean. Collectively, these patterns have been shortened to the acronym ENSO (for El Niño Southern Oscillation) and the scientists behind the new study were interested in how ENSO is affected by climate change, and how in turn this might impact future wildfires.

In order to obtain their findings, the team behind the research used a series of complex climate models and analysed data sets gathered over a large amount of time. One of those models was the Community Earth System Model (CESM), which simulated the probability of a wildfire occurring based on amount of combustible fuel, soil moisture and the statistical relationship between typical lengths of the fire season and the total combustible area. Their results were universally discouraging.

A vicious cycle

“This paper is really saying that in fire-prone places like California and Australia, we can expect future El Niño and La Niña events to have a bigger impact on fire risk in a given year,” explained Samantha Stevenson, co-author on the paper. “That's because the sensitivity of land temperature and precipitation to changes in tropical Pacific Ocean temperature is increasing due to climate change.”

Climate change will lead to increased evaporation, which will result in drier soils and fuels, thus multiplying the likelihood a wildfire will occur - and that it will be more extreme. At the same time, those very same wildfires cause significant amounts of pollution, which can be a contributing factor to climate change… thus creating a snowballing situation which continues to deteriorate.

Nothing for certain as yet

Despite the alarming results of the study, the authors of the paper were quick to point out that, much like the pollution caused by tropical storms, there are so many contributing factors to wildfires that it’s near impossible to say with certainty that they will become worse going forwards. However, if the Earth continues to warm at its current rate and El Niño events continue at theirs, the impacts are likely to be far greater.

“To me this just really highlights the importance of getting future projections of El Niño impacts and magnitudes correct,” Stevenson added.