A study by NSF-supported researchers has helped define the potentially significant contribution of permafrost thaw to atmospheric concentrations of carbon, which have already reached unprecedented levels. A lot of old carbon is stored deep in the tundra where it is locked in permafrost. As these areas start to thaw over about 15 years, large ice wedges in the soil get smaller causing pot-holing and soil depression. The newly available water prompts faster plant growth, and the carbon taken out of the atmosphere by the plants photosynthesizing is greater than the carbon released back into the atmosphere by plants respiring and microbes decomposing carbon. However, after about 50 years, as thawing continues and the soil settles even more, plants are growing faster yet, however the rate of plant respiration and old carbon release through microbes grows even bigger netting more carbon out into the atmosphere than into the soil. Read more about the research at www.nsf.gov/news/news_summ.jsp?cntn_id=114865

Credit: Zina Deretsky, National Science Foundation