July 07, 2006
|Wildfires Boosted By Global Warming||Environment|
One of the most ominous aspects of global warming is the many ways in which it is self-reinforcing. Warming causes phenomena which lead to more warming, in ever-strengthening feedback loops. Here's an example. Boston Globe:
Global warming may be largely to blame for the increasingly destructive wildfires in the Western United States in the last two decades, new research suggests.
Longer and fiercer wildfire seasons since 1986 are closely associated with warmer summer temperatures, earlier arrival of spring, and earlier snowmelts in the West, scientists reported yesterday in the online edition of the journal Science.
The new findings suggest that the most up-to-date forest management methods may be insufficient to slow the uptick in large forest fires. [...]
Westerling and his colleagues analyzed a comprehensive government database of forest fires larger than about 1,000 acres in the West since 1970. They found a dramatic increase in wildfires after 1986, with large fires four times more frequent than during the preceding years, and burning through 6 1/2 times more area. Also, the average wildfire season increased by 2 1/2 months.
Scientists had previously believed that increased wildfire activity resulted from changes in land use practices. In particular, tactics to suppress fires had allowed dead and dry vegetation to build up in Western forests, providing more fuel for fires.
But the new study shows that most of the increase in wildfires has occurred in the Northern Rocky Mountains, where few land-use changes have occurred. Also, the scientists found that 66 percent of the yearly variation in forest fires could be explained by temperature changes alone, with hotter years producing more fires.
The wildfires were also much more common in years with an early snowmelt, the researchers reported. When snow melts earlier, it allows more time for soil and vegetation to dry out, permitting fires to begin earlier in the season. On average, snowmelt in the West came about a week earlier after 1986, with spring and summer temperatures higher by about 1.6 degrees Fahrenheit.
Thomas W. Swetnam of the University of Arizona, a coauthor of the paper, said he was surprised that the study showed temperature had a greater influence than land-use changes on wildfire activity. Steven W. Running, a forestry professor at the University of Montana who was not involved in the study, said the research shows that climate change is already making its impact felt. As he talked, a forest fire burned less than a mile from his office, he said. [Emphasis added]
Atmospheric CO2 leads to warming which leads to wildfires which lead to more atmospheric CO2, and around it goes. Fiddling while the world burns.
To see just how much smoke comes from forest fires, check out these satellite images over Canada of fires that are burning right now. The immense breadth of smoke and gases is awesome, and is a sobering visualization of large volumes of CO2 being released into the air.
Two completely unrelated human activities are going to bring greater prominence to forest fires in the upcoming years; global warming along with our desire and need to sequester them. Fire is part of a natural life cycle of forests, and every time we successfully put out forest fires we create more mature forests having a greater number of large trees. Forests bulge, if you will, so when they eventually do burn they produce more CO2 than younger forests normally would. This has been known for some time and I believe there are some policies in place, that whenever feasible, allow fires to burn out naturally so long as it's safe to do so (for reasons other than CO2 release). But there's still a reserve of overly mature forests from decades past that are a ticking time-bomb. Global warming is merely the fuse.
Posted by: Jeff at July 8, 2006 01:32 PM
NASA's Terra satellite has now detected high concentrations of carbon monoxide over the areas of Canada that recently had forest fires. Carbon Monoxide - being toxic in high concentrations - has reduced the air quality.
Posted by: Jeff at July 11, 2006 03:30 PM