Forest fires. Not sure how common peat fires are - don't know almost anything about them. Looks like a much bigger deal (because it's rare, hence the ecosystem/communities are not prepared to deal with them).

Also they're having forest fires too, like every year: http://smoke.alaska.edu/current_fires.html

> Pierre Markuse, a satellite imagery processing guru, has documented some of the blazes attacking the forests and peatlands of the Arctic.

I was just there a few weeks ago. Reduced visibility in many places due to smoke, many "thank you firefighters!" signs along the road, helicopters picking up water from some of the millions of Alaskan lakes. It's still a very beautiful place.