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

Abstract

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 change1-3. Yet regional-scale impact assessments are fraught with difficulties, such as the uncertainties of regional climate-change prediction4, the specification of appopriate 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 to estimates of climate-change impacts have only been poorly explored3-7. 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.