By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
(German text translated/edited by P Gosselin)
Droughts increase the risk of forest fires; that’s logical. However it is false to reflexively assign every forest fire to climate change. There have always been droughts and forest fires. Anyone wishing to shift the blame over to climate change first has to show that the trend has already deviated from the range of natural variability. For many, that is simply too much work.
Thus they prefer to claim something and hope that nobody will bother to fact check the claim. They don’t like climate skeptics because they have the silly habit of carefully examining the facts. They prefer the silent, non-questioning audience who immediately say yes and amen in response to all alarmist claims.
And when the facts indeed do contradict their alarmist claims, they get personal. They attack the occupation of the skeptic, or education, or skin color, or, or, or.
Nowadays we can find a load of facts in the Internet. Example: forest fires in the USA. The size of the areas ravaged by forest fires is provided by a table from the National Interagency Fire Centers. Strangely the data are not offered in graphical form. You are forced to make your own, which is no problem. Most people however simply are left in the dark. Steven Goddard (Tony Heller) shows such a charts at his Real Science blog.
2004 – 2014 burn acreage trend is falling. Chart source: Tony Heller.
One cannot always just pull climate change at of his magic hat every time a forest fire appears. The University of Colorado at Boulder recently calculated that 84% of all forest and bush fires in den USA are caused by humans. Read the press release from February 2017:
Humans have dramatically increased extent, duration of wildfire season
Humans have dramatically increased the spatial and seasonal extent of wildfires across the U.S. in recent decades and ignited more than 840,000 blazes in the spring, fall and winter seasons over a 21-year period, according to new University of Colorado Boulder-led research. After analyzing two decades’ worth of U.S. government agency wildfire records spanning 1992-2012, the researchers found that human-ignited wildfires accounted for 84 percent of all wildfires, tripling the length of the average fire season and accounting for nearly half of the total acreage burned. The findings were published today in the journal Proceedings of the National Academy of Sciences.
“There cannot be a fire without a spark,” said Jennifer Balch, Director of CU Boulder’s Earth Lab and an assistant professor in the Department of Geography and lead author of the new study. “Our results highlight the importance of considering where the ignitions that start wildfires come from, instead of focusing only on the fuel that carries fire or the weather that helps it spread. Thanks to people, the wildfire season is almost year-round.” The U.S. has experienced some of its largest wildfires on record over the past decade, especially in the western half of the country. The duration and intensity of future wildfire seasons is a point of national concern given the potentially severe impact on agriculture, ecosystems, recreation and other economic sectors, as well as the high cost of extinguishing blazes. The annual cost of fighting wildfires in the U.S. has exceeded $2 billion in recent years.
The CU Boulder researchers used the U.S. Forest Service Fire Program Analysis-Fire Occurrence Database to study records of all wildfires that required a response from a state or federal agency between 1992 and 2012, omitting intentionally set prescribed burns and managed agricultural fires. Human-ignited wildfires accounted for 84 percent of 1.5 million total wildfires studied, with lightning-ignited fires accounting for the rest. In Colorado, 30 percent of wildfires from 1992-2012 were started by people, burning over 1.2 million acres. The fire season length for human-started fires was 50 days longer than the lightning-started fire season (93 days compared to 43 days), a twofold increase. “These findings do not discount the ongoing role of climate change, but instead suggest we should be most concerned about where it overlaps with human impact,” said Balch. “Climate change is making our fields, forests and grasslands drier and hotter for longer periods, creating a greater window of opportunity for human-related ignitions to start wildfires.”
While lightning-driven fires tend to be heavily concentrated in the summer months, human-ignited fires were found to be more evenly distributed across all seasons. Overall, humans added an average of 40,000 wildfires during the spring, fall and winter seasons annually—over 35 times the number of lightning-started fires in those seasons. “We saw significant increases in the numbers of large, human-started fires over time, especially in the spring,” said Bethany Bradley, an associate professor at University of Massachusetts Amherst and co-lead author of the research. “I think that’s interesting, and scary, because it suggests that as spring seasons get warmer and earlier due to climate change, human ignitions are putting us at increasing risk of some of the largest, most damaging wildfires.” “Not all fire is bad, but humans are intentionally and unintentionally adding ignitions to the landscape in areas and seasons when natural ignitions are sparse,” said John Abatzoglou, an associate professor of geography at the University of Idaho and a co-author of the paper. “We can’t easily control how dry fuels get, or lightning, but we do have some control over human started ignitions.”
The most common day for human-started fire by far, however, was July 4, with 7,762 total wildfires started on that day over the course of the 21-year period. The new findings have wide-ranging implications for fire management policy and suggest that human behavior can have dramatic impact on wildfire totals, for good or for ill. “The hopeful news here is that we could, in theory, reduce human-started wildfires in the medium term,” said Balch. “But at the same time, we also need to focus on living more sustainably with fire by shifting the human contribution to ignitions to more controlled, well-managed burns.” Co-authors of the new research include Emily Fusco of the University of Massachusetts Amherst and Adam Mahood and Chelsea Nagy of CU Boulder. The research was funded by the NASA Terrestrial Ecology Program, the Joint Fire Sciences Program and Earth Lab through CU Boulder’s Grand Challenge Initiative.”