There appears to be a very clear linkage between the increased severity of wildfires and a little as 1-degree of increase in global warming.  Kevin Drum writes at Mother Jones about why California's wildfires have been getting worse, larger, and more frequent.  It may be even worse in British Columbia and the Pacific Northwest.  Drum says that roughly half of the increase in western wildfire activity is due to land use issues - people building in undeveloped areas they ought not to build in, basically.  The other half is due to global warming.  Higher temperatures lead to reduced snowpack and an earlier melt, producing a longer and drier fire season. 

In addition, Drum refers to an article that Tom Kenworthy wrote at the American Progress entitled "What a 1-Degree Temperature Increase Means for Wildfires".  In it, Kenworthy talks about research done that indicates that "inaction on climate change will cost the western United States dearly".  He says that research published by Harvard University scientists in the Journal of Geophysical Research predicts that areas burned by wildfires could increase by 50% by 2050 "with even larger increases in the Pacific Northwest and Rocky Mountain West."  Those increases will have large impacts on the amount of carbon released into the atmosphere, the health of people downwind and the costs of fighting the fires. 

And, this is happening now.  "Since 2000, wildland fires in the United States have burned an average of more than 7 million acres a year, about double the average acreage for the previous four decades."

One of the major contributing factors according to Kenworthy, also related to climate change, is a "so far unchecked epidemic of mountain pine beetles that has killed millions of acres of trees from Colorado north into Canada has laid the foundation for a potentially large increase in catastrophic fires"  Warmer winter temperatures spare the mountain pine beetles, allowing them to kill millions of acres of forest, stressing the trees and making them less resistant to stress and more prone to fire.  The beetles have killed off 35 million acres in British Columbia, which has had a devastating fire season this year with more than 155,000 acres burned.  "Destruction of trees by the mountain pine beetle, combined with climate change and fire, makes for a dangerous feedback loop. Dead forests sequester less carbon dioxide. Burning forests release lots of carbon dioxide into the atmosphere. More carbon dioxide adds to climate change, which raises temperatures, stresses forests, and makes more and bigger fires more likely."