Repost from the San Francisco Chronicle

Scientists say widespread wildfires can make global warming worse

Washington Post, October 20, 2015 7:26pm

 

In not much more than a month, leaders from around the world will assemble in Paris in order to — hopefully — find a way to cap the world’s greenhouse gas emissions and bring them down to safe levels.

But there’s a problem. There are some greenhouse gas sources that these leaders can’t fully control — and in some cases, reasons to think that these sources may grow in the future. The point is being driven home this year by raging peat fires in Indonesia, which have already contributed more than a billion tons of carbon dioxide equivalent emissions to the atmosphere — as much as Japan produces in a year from fossil fuels.

Indonesia isn’t the only part of the world where fires — which in many areas are expected to be worsened by climate change — could provide a new net source of emissions to the atmosphere. Another region of major worry is the world’s boreal or northern forests, which store a gigantic amount of carbon in trees as well as soils and frozen permafrost layers beneath the surface. Permafrost is a repository of carbon that has accumulated over many thousands of years, but could now be released back to the atmosphere on a much shorter time scale.

Alaska’s dramatic wildfire season this year — where more than 5 million acres of largely black spruce forests burned — raised great concerns about how events such as this could make global warming worse. The fear here is of a sort of triple whammy — forests release the carbon stored in trees back to the atmosphere when they burn; the forests contain a deep upper soil layer that also burns off, releasing more carbon; and finally, beneath all of that is the carbon rich permafrost, which becomes exposed after fires and can then thaw and start to emit.

And now, a new study in Nature Climate Change reaffirms these concerns about the emissions of northern fires. The study, led by Ryan Kelly of the University of Illinois at Urbana, looked at a particular Alaskan region that has seen intensive burning of late — the remote Yukon Flats. The researchers confirmed that the recent fires have been releasing much of the carbon that has been stored up over hundreds of years.

In addition, the researchers also determined that over time, change in fires patterns were by far the largest factor in how much carbon the ecosystem stored.

The new research reaffirms that fire is a powerful determinant of how much carbon resides in land, rather than in the air, across our globe.