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Background

Objectives

Building upon on-going large, integrated projects (THRESHOLDS and DAMOCLES FP6 IPs, and the ARCTOS network) the project Arctic Tipping Points (ATP) will identify the elements of the Arctic marine ecosystem likely to show abrupt changes in response to climate change, and will establish the levels of the corresponding climate drivers inducing regime shift in those tipping elements. In addition, state-of-the-art oceanographic, ecological, fisheries, and economic models will determine the effect of crossing those thresholds for the Arctic marine ecosystems, and the associated risks and opportunities for economic activities dependent on the marine ecosystem of the European Arctic.

Last Updated (Wednesday, 20 May 2009 09:23)

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Progress beyond state of the art

The concept that ecosystems do not respond smoothly to changing pressures has existed for the last 30 years (May 1977), but the analyses of ecological tipping points and regime shifts remain conceptual in nature (Scheffer et al. 2001, Lenton et al. 2008). In the same period statistical frameworks for analysing such phenomena have been developed in other disciplines, such as climate research and econometrics (Zeileis et al. 2003, May et al. 2008), and their use in ecology has been promoted recently through the THRESHOLDS integrated project (FP6, contract 003933-2, Andersen et al. subm.). As a theoretical framework to explain regime shifts improves (Steele 2004), it becomes apparent that regime shifts are triggered by exceeding a particular critical threshold in the driving variable (May 1977). One example is how changes in climate drivers can force marine ecosystems into a new structural and functional state. Regime shifts are often persistent in that reverting the ecosystem to the original state often requires far greater changes in the driver than what prompted the initial shift. In the worst cases, reversion may prove impossible over managerial time scales. Anticipating where these tipping points are is critical in setting targets to conserve marine ecosystems (Groffman et al. 2006). Unfortunately, most research on regime shifts has been retrospective in nature, focussing on the their detection and analysis after tipping points have been passed (e.g. Mantua 2004). The prediction of ecological thresholds remains elusive, a major bottleneck for the applicability of the concept.

Last Updated (Tuesday, 02 June 2009 12:39)

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Concepts and objectives

There is mounting evidence that ecosystem response to certain types or magnitudes of extrinsic pressures (climate, human impacts, etc.) is often abrupt and non-linear, leading to a significant reorganization of system properties and processes. These ecosystem changes are known as regime shifts (Scheffer et al. 2001). Such non-linear responses are often initiated by qualitative changes in the structure or function of the ecosystem, and are so fundamental that the impacted ecosystems respond to new pressures in completely different manners than the original ecosystem did (May 1977). Regime shifts arise, for instance, from the introduction of alien species or the loss of key species in the ecosystems. These changes can result in alterations of the most basic ecosystem parameters, including food-web structure, the flow of organic matter and nutrients through the ecosystem, or the patterns of space occupation, leading to a cascade of changes in the ecosystem. Climate drives both community structure and key organismal functions, so it is hardly surprising that regime shifts identified from marine ecosystems are often linked to climate (Cushing 1982, Steele 2004).

Last Updated (Tuesday, 02 June 2009 12:40)

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