Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
SEARCH Vision and Core Hypotheses
James Morison1
1Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105-6698, USA, Phone 206-543-1394, Fax 206-616-3142, morison@apl.washington.edu
The Study of Environmental Arctic Change (SEARCH) is motivated by observations indicating significant, interrelated, atmospheric, oceanic, and terrestrial changes have occurred in the Arctic in recent decades. During the early 1990's the influence of Atlantic water in the Arctic Ocean became more widespread and intense. The boundary between the eastern and western types of haloclines shifted from over the Lomonosov Ridge to roughly parallel to the Alpha and Mendeleyev ridges. The Atlantic water cores over the major ridge systems warmed. The observed shift in frontal positions corresponded with a change in sea ice drift. There has been a 3-4% per decade decrease in sea ice extent and a 43% reduction in central basin ice thickness in recent decades. Atmospheric pressure and circulation patterns changed consistent with an observed decrease in the annual mean sea level atmospheric pressure over the Arctic.
There have been changes on land as well. For example, changes in air temperature have been attended by reductions in spring snow cover. Arctic glaciers have exhibited negative mass balances, paralleling a global tendency. Various studies point to increased plant growth, increased fire frequency, and thawing and warming of permafrost. The physical changes are affecting ecosystems and society, impacting transportation, infrastructure, resource development, and food gathering. The changes appear to be part of an interrelated, pan-Arctic complex which many of us have nicknamed Unaami (Siberian Yup’ik word for tomorrow).
SEARCH is conceived as a broad, interdisciplinary, program of long-term observation, paleo and retrospective studies, analysis, and modeling with a core aim of understanding Unaami. We don't know Unaami's full extent or future course, but we think we can understand it because the recent observations of the changing environment have given us new insights into how the Arctic system functions. Multivariate analysis of many variables has quantified the notion of a complex of interrelated changes. We express the insights we have already gained, and our uncertainties, by framing four core SEARCH hypotheses. These are:
Unaami is related to a spin up of the atmospheric Polar Vortex. - Several modeling studies and an observed relaxation of some of the changes toward climatology with recent decreases in Polar Vortex strength tend to support this hypothesis.
Unaami is a component of climate change. - Because changes in the strength of the Polar Vortex (as indicated for example by the Arctic Oscillation index) represent a fundamental mode of atmospheric variability, Unaami is likely to be tied to climate change.
Feedbacks between the ocean, the land, and the atmosphere are critical to Unaami. - Such feedbacks include those within the Arctic and global effects such as changing albedo and moderation of the global ocean overturning circulation.
The physical changes of Unaami have large impacts on the Arctic ecosystems and society. - This certainly appears to be true for the Arctic. Given the hypothesized connections with the atmospheric circulation of the Northern Hemisphere and with global climate, the impacts are potentially much broader.
The recognition of a systematic pattern of pan-Arctic change and the formulation of these hypotheses exemplifies a change in the way many of us think about the Arctic environment and compels us to seek a systematic program of observation, analysis, and application to understand what is happening and respond appropriately.
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