How can a glacier be a source of the organic carbon? His curiosity peeked [sic], in spring 2009, Hood’s Ph.D. student, Jason Fellman, collected samples from 11 watersheds along the Gulf of Alaska from Juneau to the Kenai Peninsula. The samples were analyzed to determine the age, source, and biodegradability of organic matter derived from glacier inputs.
“We found that the more glacier there is in the watershed, the more carbon is bioavailable. And the higher the percentage of glacier coverage, the older the organic material is – up to 4,000 years old,” said Scott.
Hood and Scott hypothesize that forests that lived along the Gulf of Alaska between 2,500 to 7,000 years ago were covered by glaciers, and this organic matter is now coming out. “The organic matter in heavily glaciated watersheds is labile, like sugar. Microorganisms appear to be metabolizing ancient carbon and as the microorganisms die and decompose, biodegradable dissolved organic carbon is being flushed out with the glacier melt,” said Scott.
How much? “Our findings suggest that runoff from glaciers may be a quantitatively important source of bioavailable organic carbon for coastal ecosystems in the Gulf of Alaska and, as a result, future changes in glacier extent may impact the food webs in this region that support some of the most productive fisheries in the United States,” said Hood.
Bold mine. Now, it would seem that it had to have been warmer at some point for those forests to have grown, then it cooled and the glaciers came down, and now some glaciers are melting; why, it almost sounds like some kind of natural cycle!