Arnold Schwarzenegger injects Hollywood glamour wherever he goes. When California鈥檚 governor inspected the 2000 square kilometres charred in last week鈥檚 wildfires, he looked every bit the movie hero. The script worked out well, too. Arnie won praise for mobilising rescue workers quickly and even the wind turned in his favour, dying down in time for firefighters to limit the damage.
Yet there is an alternative plot line that Schwarzenegger would not be pleased with. It鈥檚 the story being told by wildfire experts. In this version, state and federal policies are partly to blame for the fires, and the moral of the tale is that policies must change if the million people ordered to evacuate last week are to be spared a repeat performance. There is accumulating evidence that rather than suppressing fire, we should allow it to return to the role it used to play in Californian ecosystems.
The latest evidence comes from a study of the era before European settlers arrived; a time when wildfires were sparked by lightning or started by Native Americans, who used them to for a variety of purposes including flushing out wildlife when hunting. Ethnographic studies and data from tree rings suggest that 18,000 square kilometres burned every year in California (Forest Ecology and Management, ). That鈥檚 almost as much as the area that burned across the whole of the US between 1994 and 2004.
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In other words, says Nicholas Clinton at the University of California, Berkeley, last week鈥檚 wildfires 鈥� labelled 鈥渆xtreme events鈥� and judged the worst national disaster since hurricane Katrina 鈥� would have been unremarkable prior to 1800.
So what happened? Wilderness has been converted to agriculture, reducing the area that might burn, but the remainder would still experience large fires if forest managers allowed it. Instead, the authorities tend to suppress blazes.
It is an understandable response: California is one of the more densely populated states in the US, and residents inevitably want nearby fires stamped out as quickly as possible. Nevertheless, this small-picture attitude may be making the big picture worse. Richard Minnich, at the University of California, Riverside, has compared wildfires in California with those across the Mexican border, where land is managed less intensively. A similar amount of land burns on both sides, but the US fires are less frequent and larger because smaller fires 鈥� which use some of the available fuel 鈥� occur less often. That means that US fires are more likely to get out of control in high winds, as happened last week.
One solution would be to allow small fires to burn out naturally, at least in areas away from homes, says Clinton. Such policies have the backing of many wildfire experts, but remain controversial, not least with members of the voting public who live near forests, so progress in this direction has been minimal. Minnich鈥檚 research, for example, is now almost 25 years old (). Last week鈥檚 events show that the script has not changed a great deal in a quarter of a century 鈥� just be prepared for the sequels.
