The Lengthening of the Wildfire Season due to Climate Change

The last couple of year’s wildfires have made more appearances in the news with their frequency and magnitude of devastation.  A wildfire is defined as an uncontrolled, quickly spreading fire in an area of combustible vegetation that is unwanted or unplanned. A wildfire season is when wildfires are more likely to occur, which is usually from the spring when the snow melts until full foliage is present. Thirty-five Years of meteorological data has recently been published and confirms a lengthening in the season of wildfires (NASA, 2015). The study observed four variables that affect the length of fire seasons temperature, humidity, precipitation, and wind speed. A combination of high temperatures, low humidity, rainless days, and high winds make wildfires more likely to spread and lengthens fire seasons (NASA, 2015). Research found that fire seasons in parts of the western United States and Mexico, Brazil, and East Africa face wildfire seasons more than a month longer than they were 35 years earlier.

Figure 1.1 Changes in Fire Season Length 1979-2013 (NASA)

The overall 18.7% length increase worldwide is attributed to more rain-free days and hotter temperatures (Cochrane, 2015). The longer season in The United States is attributed to changes in the timing of snowmelt, vapor pressure, and the timing of spring rain, which all are linked to global warming and climate change. Not only are seasons becoming longer but it was found that they are becoming more frequent regardless of length.

Figure 1.2 Changes in Frequency of Long Fire Seasons 1979-2013 (NASA)

The researchers found that the number of rain-free days has increased by 1.31 days per decade. The average temperature on vegetated land increased by 0.185 degrees per decade, while the annual relative humidity dropped by 0.127 percent per decade. Conversely, the mean annual precipitation worldwide is the same, according to Cochrane. "It's still the same amount of rainfall, just concentrated in fewer days." This means more dry days when conditions are agreeable to burning (Cochrane, 2015).

Increased wildfire seasons lead to more destruction of not only woodlands and other habitats but in property and the relocations of people’s lives. This all leads to substantial investments in fire suppression by the government (CNBC, 2015). Since 2000 the US Forest Service has doubled its spending from 540 million dollars to 1.7 billion dollars (Goldenburg, 2013).  To feed this needed fund to suppress fires the US government is pulling funding from other Forest Service areas to compensate, in turn leaving these other groups short on funds. The Deferred Maintenance and Infrastructure Improvement program is projected to lose 95% of its budget, Roads 46%, Facilities 68%, and other such areas as recreation, and habitat management (USDA Forest Services, 2015). 

As the wildfires burn they add more CO₂ into the atmosphere contributing to the global warming which is enabling these fires to occur. Future outlooks show a somewhat cyclic effect of increased funds needed to fight increased fires which are increasing preferable conditions for future wildfires. Currently the only ways to limit the potential damage is public education on potential fire starters, cheaper more effective fire retardants, and a better allocation of funds.