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Executive Summary of SEARCH Science Plan
It is clear that a complex suite of significant, interrelated, atmospheric,
oceanic, and terrestrial changes has occurred in the Arctic in recent
decades. This event is affecting every part of the arctic environment
and is having repercussions on society. There is evidence that these changes
are connected with the rising trend in the Arctic Oscillation (AO),
a mode of atmospheric variability that is potentially active over a broad
range of time scales, including climatic time scales, and that involves
changes in the strength of the atmospheric polar vortex. There is theoretical
evidence that the positive trend observed in the AO index might be indicative
of greenhouse warming. It is unclear what feedback processes on climate
or ecosystems may be involved in the recent changes, or what the long-term
impacts may be. Because the observed changes have made it harder for those
who live in the north to predict what the future may bring, we have given
the name Unaami (based on the Yup’ik word for "tomorrow")
to the complex of intertwined, pan-Arctic changes.
The Study of Environmental Arctic Change (SEARCH) has been conceived as a broad, interdisciplinary, multiscale program with a core aim of understanding Unaami. Part of gaining this understanding will be to determine the full scope of Unaami. As a working definition based on present knowledge, we define Unaami as the recent and ongoing, decadal (e.g., 3—50 year), pan-Arctic complex of interrelated changes in the Arctic. These changes include, among other things, a decline in sea level atmospheric pressure, an increase in surface air temperature, cyclonic ocean circulation, and a decrease in sea ice cover. The physical changes are producing changes in the ecosystem and living resources and affecting the human population. The changes are affecting local and hemispheric economic activities such as shipping and fisheries totaling billions of dollars. These biological and societal consequences may be considered part of Unaami. Although the dynamics are different, the situation is similar to the El Niño-Southern Oscillation (ENSO) phenomenon.
Activities undertaken as part of SEARCH are guided by a series of hypotheses. The first hypothesis is that:
Unaami is related to or involves the Arctic Oscillation.
Here the AO phenomenon is broadly interpreted as describing the strength of the polar vortex as shown by the AO and related teleconnection indices. A key objective of SEARCH will be to understand the arctic-wide interactions inherent in Unaami and their links to a rising AO in a rigorous way. Testing this hypothesis will tell us much about the interaction between the atmosphere, ocean, and land. It will tell us how Unaami is tied to the global atmosphere.
The second hypothesis is that:
Unaami is a component of climate change.
Because the AO is a fundamental mode of atmospheric variability, Unaami will be tied to climate change through the AO as well. Unaami may also be tied to global climate change through its impact on the global ocean thermohaline circulation. The objective is to understand how Unaami fits into the larger picture of climate change.
The third hypothesis is related to the first two:
Feedbacks between the ocean, the land, and the atmosphere are critical to Unaami.
These feedbacks could determine the role of Unaami and the Arctic in climate change. Such feedbacks include surface albedo and cloud changes as well as air chemistry processes, and the global ocean overturning circulation.
The fourth hypothesis is that:
The physical changes of Unaami have large impacts on the arctic ecosystems and society.
This is true whether Unaami is related to climate change or not. Many important consequences involve the complex interaction of Unaami and non-climate related human activity. This hypothesis is the motivation for determining the impact of Unaami on the ecosystem and society.
The SEARCH strategy is conditioned in part by the knowledge that a number of long-term, large-scale observing systems have disappeared or are in danger of disappearing. The strategy includes four major activities:
- Long-term observations to detect and monitor the environmental changes
- Modeling to synthesize observations, test ideas about the coupling between different components of Unaami, and to predict Unaami’s future course
- Process studies to understand potentially important feedbacks
- Application of what we learn to understanding the ultimate impact of the physical changes on the ecosystems and societies, and to distinguish between climate-related changes and those due to other factors such as resource utilization, pollution, economic development, and population growth.
Various components of the SEARCH program are at different stages of readiness. Many of the long-term physical observations, for example, can be started immediately. Much of the application component has yet to be developed. This science plan must, therefore, be considered a living document that will evolve as SEARCH progresses.
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