Global Warming and Arctic Polar Amplification
Why is the Arctic warming at twice the global average?
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The Arctic has warmed at about twice the global average of temperature increase and this is termed polar amplification. Several factors cause this: the resulting decrease in sea ice and snow has contributed to the warming through the ice-albedo feedback; with warming an increase in water vapour, a greenhouse gas, has been observed; and warmer ocean currents in the North Atlantic and the North Pacific have reduced the amount of sea ice (Walsh, 2014).
Past research has found ocean heat transport into the Arctic increases with global warming; recent research explains part of the temperature rise by the increasing gradient of vertical temperature difference. That is, the increasing temperature as the ocean currents warm, gives a greater temperature difference between the lower warm ocean currents and the near freezing water under the ice. This increased vertical gradient drives horizontal heat transport into the Arctic, with modelling demonstrating a contribution of 20% to polar amplification (Beer, Eisenman & Wagner, 2020).
High latitude boreal forests and tundra soils contain large amounts of carbon, about 390Gt. Northeast Greenland low prostrate shrub tundra is dominated by the shrubs Dryas octopetala white dryad, Cassiope tetragona Arctic white heather and Salix arctica Arctic willow (Sjögersten, et al., 2003).
Climate change warming is expected to affect the release of greenhouse gases from Arctic Circle and high latitude tundra. Increased temperature will allow decomposition of previously frozen organic matter. Increased carbon dioxide CO2 will be released, nitrous oxide N2O will vary between being released and uptake, and methane CH4 may be a net uptake, a reduction, but overall, the CO2 release will result in an increase in warming potential (Zhou, et al., 2016).
Decomposition of the tundra stored organic matter is complex, as are the fluxes of CO2, N2O and CH4 between the atmosphere and stores in the soil.
