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The Trouble with Humans

posted Mar 24, 2017, 2:53 PM by Joe Christy
It’s a maxim amongst wildland firefighters that the three most important causes of wildland fire are men, women, and children (though obviously not in that order). The new era of big data analysis and the vast accumulated US weather data sets from the last century and a half are now bearing out the factual truth of that maxim. Two recent studies published in the Proceedings of the National Academies of Sciences expose two facts.
The first study, Human-caused climate change is now a key driver of forest fire activity in the western United States, looked at fuel aridity, which is in a sense the flipside of our old friend fuel moisture, and which has an obvious correlation with fire severity. Scientists from Lamont–Doherty Earth Observatory, University of Idaho, and the NASA Goddard Institute for Space Studies have been able to parse out, first in California, then across the West, the impact of human caused climate change from the statistically normal oscillations in weather, e.g. El Nino. They found that while the maximal severity of California’s annual summer drought is not increasing, the frequency of extreme droughts is, and that increased frequency is primarily due to the component of warming of the earth’s atmosphere correlated with increase of greenhouse gasses. Across the west, they found that “human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984”.
In the second, Human-started wildfires expand the fire niche across the United States, using the government wildfire data for the entire US, scientists from the Universities of Colorado, Massachusetts, and Idaho, found that “human-started wildfires accounted for 84% of all wildfires, tripled the length of the fire season, dominated an area seven times greater than that affected by lightning fires, and were responsible for nearly half of all area burned.” In our eco-region of California, 97% of wildfires are being caused by humans, who have doubled the length of fire season (though in 2014-2015 we saw one year’s fire season merge into a second), and are responsible for 89% of the area burned!
In other words, humans are both making our environment more susceptible to large, severe wildfires, and supplying the sparks that start those fires. Our mission is all the more important.