Spent quite a bit of my time sunday night trying to absorb a review article in Bioscience on the thawing permafrost and the carbon cycle. The thawing of permafrost increases the ability of microbes to release carbon contained in permafrost organic matter. The international group of scientists estimate that permafrost C pool is double the amount of the atmospheric C pool. A significant transfer of C from permafrost into the atmosphere is something we need to be concerned about because 1) the shear size of the permafrost C pool (permafrost covers 22% of the northern hemisphere landmass), and 2) the potential for a positive feedback cycle between C release, further heating, further C release...

One issue of particular concern to the scientists is the fact that water goes through a phase transition as it switches from ice to water. The scientists worry that because of this, and with larger temperature increases expected at higher latitutes, we might hit a threshold point where permafrost system dynamics change rapidly. The dynamics of permafrost thawing still needs more research to know exactly how events will play out.

Thawing permafrost is the largest "vulnerable" C pool, however, there are 4 other major C pools that potentially are vulnerable to climate change:

• wetland drying
• fires/land-use change
• methane hydrates
• ocean biological pump

To learn more about permafrost, visit the Permafrost wikipedia page, or What is Permafrost by the Geological Survey of Canada.