One of the quirks of global warming is that average temperatures in the polar regions are rising a lot faster than they are in the rest of the world. (See here for an explanation.) That's not exactly reassuring, since a lot of the climate impacts we care about, especially the melting of Greenland and Antarctic glaciers and the potential release of methane gas from the tundra, will occur in exactly those areas. And today the AP's Charles Hanley takes a look at two more nasty climate feedback mechanisms at work in the northern latitudes: beetles and forest fires.

The beetles are already causing all sorts of chaos—they're probably one of the most significant impacts of climate change we've seen to date. In places like the Yukon and Pacific Northwest, warmer summers have sped up the reproductive cycle of bark beetles, while fewer larvae are being killed off during the milder winters. The beetles are then feasting on forests, reducing their ability to absorb carbon-dioxide—which, in turn, helps boost global temperatures even further. In recent years, an unprecedented epidemic of mountain pine beetles has gobbled up 35 million acres of forest in British Columbia, and the bugs are expected to kill 80 percent of the area's lodgepole pines. A cheerful study in Nature last year forecast that, by 2020, the pine beetles would transform British Columbia's forests from a net carbon absorber to a net carbon emitter. (Beetle invasions down in the western United States are on the way, too.)

If that wasn't enough, there's also the overlapping fire threat. In Siberia, the hotter, drier weather has turned eight of the past ten summers into "extreme wildfire seasons." In Canada, area burned is double what it was in the 1970s, despite better firefighting capacity. And, of course, beetle or other insect infestations that leave lots of dead, dry wood in their wake also help increase the chances for fires. (Although in Siberia, scientists seem to be less obsessed with beetles and spend more time worrying that warmer temperatures will lead to a Siberian moth onslaught. Basically the same thing.)

Interestingly, according to the Nature study, the dread beetle feedback hasn't yet been incorporated into the climate models used to predict the future course of warming. So here's a good example of how those much-lambasted models are incomplete—except it's not really comforting news. As little as a decade ago, no one knew this sort of beetlemania was even possible, which is why many scientists are wondering, uneasily, what other surprises a warming world might bring.

(Flickr photo credit: johnhallmen)