Like every October, when the Santa Ana winds strengthen wildfires in southern California, the debate is on. Is the seeming increase in recent California fires, as Gov. Schwarzenegger suggested this summer, due to higher temperatures and droughts brought about by global warming? Or are the fires a lot like hurricanes—similar in strength and number over the past century, but perceived as a lot more damaging now because there are simply a lot more houses (and camera crews) in the way?

One of the Los Angeles-area wildfires, whipped by Santa Ana winds gusting to 50 miles per hour, threatened to break out to the Pacific Ocean Tuesday, forcing the evacuation of thousands of residents and torching parts of Los Angeles and the San Fernando Valley. Gov. Arnold Schwarzenegger declared a state of emergency for the area.

The answer, it seems, is a little bit of everything. Scientists figure that climate change, including melting snowpacks and warmer temperatures, primes the ground for the naturally-ocurring fires and makes wildfire season last longer. Other causes include environmental strategies that appear to have backfired—like snuffing out small wildfires that traditionally eliminated underbush which now serves as kindling.

But the majority of new development in southern California also takes place in fire-prone areas (as the L.A. Times pointed out in its five-part series this summer, and as The Onion wryly noted). That kind of pell-mell growth is like “pitching a tent on the railroad tracks,” the Washington Post argued.