The permafrost carbon feedback: the impact of global warming on Arctic ecosystems

The impact of global warming on Arctic ecosystems

The Arctic is warming faster than the rest of the planet, and this is affecting processes at all scales, from the molecular to the ecosystem. This article looks at the melting of permafrost, which not only impacts on landscapes, habitats and human activity, but could lead to massive increases in greenhouse-gas emissions

Philip Wookey

Permafrost in the Mackenzie Uplands, Northwest Territories of Canada. Note the ‘polygons’, which form over many years due to the frozen ground shrinking in extreme low temperatures. For scale, the long axis of the image is about 300 metres

Despite extremes of cold and months of darkness, the Arctic supports complex food chains, from algae and cyanobacteria to large mammals. When these organisms die, their remains become part of the ‘detritus’ system. Organic detritus which does not fully decompose plays an important role as organic matter in soil in all environments. But in cold environments such as the Arctic, incomplete decomposition can lead to massive accumulations of organic matter, and thus carbon, in soils and sediments.

A similar process in UK uplands following the retreat of the British-Irish ice sheet between 27,000 and 11,500 years ago produced our peatlands and blanket bogs, where cold and wet conditions have restricted decomposition processes.