Relative impacts of human-induced climate change and natural climate variability


Assessments of the regional impacts of human-induced climate change on a wide range of social and environmental systems are fundamental for determining the appropriate policy responses to climate change1,2,3. Yet regional-scale impact assessments are fraught with difficulties, such as the uncertainties of regional climate-change prediction4, the specification of appropriate environmental-response models5, and the interpretation of impact results in the context of future socio-economic and technological change6. The effects of such confounding factors on estimates of climate-change impacts have only been poorly explored3,4,5,6,7. Here we use results from recent global climate simulations8 and two environmental response models9,10 to consider systematically the effects of natural climate variability (30-year timescales) and future climate-change uncertainties on river runoff and agricultural potential in Europe. We find that, for some regions, the impacts of human-induced climate change by 2050 will be undetectable relative to those due to natural multi-decadal climate variability. If misleading assessments of—and inappropriate adaptation strategies to—climate-change impacts are to be avoided, future studies should consider the impacts of natural multi-decadal climate variability alongside those of human-induced climate change.

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Figure 1: Relative impact of climate change on runoff.
Figure 2: Relative changes in mean wheat yield at a national scale.


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Model data were obtained through the Climate Impacts LINK Project. This work was supported by DGXII of the Commission of the European Community.

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Correspondence to Mike Hulme.

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Hulme, M., Barrow, E., Arnell, N. et al. Relative impacts of human-induced climate change and natural climate variability. Nature 397, 688–691 (1999).

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