Past and future global transformation of terrestrial ecosystems under climate change
Future predictions from paleoecology Terrestrial ecosystems will be transformed by current anthropogenic change, but the extent of this change remains a challenge to predict. Nolan et al. looked at documented vegetational and climatic changes at almost 600 sites worldwide since the last glacial maximum 21,000 years ago. From this, they determined vegetation responses to temperature changes of 4deg to 7degC. They went on to estimate the extent of ecosystem changes under current similar (albeit more rapid) scenarios of warming. Without substantial mitigation efforts, terrestrial ecosystems are at risk of major transformation in composition and structure. Science, this issue p. 920 Global vegetation change since the Last Glacial Maximum is used as an indicator of transformation under warming scenarios. Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial to interglacial transition, which was comparable in magnitude to warming projected for the next century under high emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios. Our results indicate that terrestrial ecosystems are highly sensitive to temperature change and suggest that, without major reductions in greenhouse gas emissions to the atmosphere, terrestrial ecosystems worldwide are at risk of major transformation, with accompanying disruption of ecosystem services and impacts on biodiversity.
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