Which specific feedback mechanism contributes to accelerated permafrost thaw in Arctic regions?
The primary feedback mechanism that contributes to accelerated permafrost thaw in Arctic regions is the permafrost carbon feedback. Permafrost is ground that remains frozen for at least two consecutive years. Arctic permafrost contains vast quantities of organic carbon, accumulated from dead plants and animals over thousands of years. This carbon is preserved in the frozen state because the cold temperatures inhibit decomposition. As Arctic temperatures rise due to climate change, the permafrost begins to thaw. When permafrost thaws, the organic matter within it becomes available for decomposition by microorganisms. These microorganisms break down the organic carbon, releasing carbon dioxide (CO2) and methane (CH4) into the atmosphere. Both CO2 and CH4 are potent greenhouse gases that trap heat and contribute to global warming. The release of these greenhouse gases from thawing permafrost further warms the Arctic region, leading to more permafrost thaw. This creates a positive feedback loop, where the initial warming triggers the release of greenhouse gases, which in turn causes more warming and more permafrost thaw. This feedback loop accelerates the rate of permafrost thaw and the release of carbon into the atmosphere, amplifying the effects of climate change. The thawing permafrost can also lead to other environmental problems, such as ground subsidence, infrastructure damage, and the release of previously frozen bacteria and viruses.