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The Local and Remote Mechanisms of Arctic Amplification: Friend or Foe?
Thursday, 27 September 2018, 2:00
Thursday, September 27, 2018. 2:00PM. The Local and Remote Mechanisms of Arctic Amplification: Friend or Foe? Patrick Taylor, NASA Langley. Sponsored by NOAA GFDL. More information here.
Over the last 30 years, rapid and, in many cases, unprecedented changes to Arctic temperatures, sea ice, snow cover, land ice, and permafrost have occurred. While the Arctic may seem far away, changes in the Arctic climate system have a global reach, affecting sea level, the carbon cycle, atmospheric winds, ocean currents, and potentially the frequency of extreme weather in northern mid-latitudes. State-of-the-art climate models are able to capture the rapid nature of recent Arctic climate change (a.k.a. Arctic Amplification), while also disagreeing more in the Arctic than anywhere else. In part, the large spread in climate projections of Arctic Amplification are due to our lack of understanding of the root cause(s) of rapid Arctic climate change, specifically the balance between the local and remote forcing mechanisms. The local mechanism represents the combined surface albedo (radiative) and ice-insulation (non-radiative) feedbacks whereby a warmer Arctic with less sea ice stores more energy in the ocean in summer via the surface albedo feedback supporting increased surface turbulent fluxes in fall/winter. Alternatively, the remote mechanism acts through changes in the non-polar (tropical and mid-latitude) circulation and increases atmospheric poleward heat transport into the Arctic and warms, moistens, and produces a cloudier Arctic atmosphere. Recent research points to a role for both the local and remote mechanisms and in fact the manner in which these mechanisms interact may be the most critical. Using a regional, process-oriented partitioning of the inter-model spread, we argue that differences in seasonal energy exchanges in sea ice retreat regions accomplished by increased absorption and storage of solar insolation in summer and increased surface turbulent fluxes in fall/winter are the leading cause of the inter-model spread. Moreover, models that more widely disperse the energy drawn from the surface in sea ice retreat regions Arctic-wide warm more, implying an important contribution of the local Arctic atmospheric circulation response to the inter-model spread. Our recent results point to two important findings: (1) the principle mechanisms driving the inter-model spread in AA operate on regional not Arctic-wide scales, and (2) reductions in the inter-model spread require an improved process representation of atmosphere-ocean-sea ice interactions in sea ice retreat regions.
Location NOAA GFDL, Smagorinsky Seminar Room, Princeton University, Princeton, NJ