Changes in Permafrost and Carbon Cycle in the Arctic

Permafrost has received much attention recently because surface temperatures are rising in most permafrost areas of the Earth, which may lead to permafrost thaw. Thawing of permafrost has been observed at the southern limits of the permafrost zone and this can lead to changes in ecosystems, in water and carbon cycles, and in infrastructure performance. Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. Accounting for C stored deep in the permafrost more than triples previous high latitude inventory estimates, with this new estimate equivalent to twice the atmospheric C pool. Thawing of permafrost with warming occurs both gradually and catastrophically, exposing organic C to microbial decomposition. If the current trends in climate continue, warming of permafrost will eventually lead to widespread permafrost thawing in the colder permafrost zones. Examination of past trends in permafrost conditions and distribution (especially during the last glacial-interglacial cycle) can facilitate better understanding of the possible rates and pathways of permafrost degradation in the future. The main reasons for this are: 1) the main present-day features in permafrost distribution both vertically and laterally were formed during the last 100,000 years and 2) we can expect that with persistent future climate warming, the first permafrost to begin to thaw will be the youngest Little Ice Age permafrost, followed by mid- and late-Holocene permafrost, and last to thaw would be the Late Pleistocene permafrost. This presentation will describe our knowledge of permafrost development in Eurasia during the last glacial-interglacial cycle. The possible consequences of permafrost degradation to the global carbon cycle also will be discussed.