Environ. Res. Lett. 8, 044018 (2013)

Climate change could potentially lead to fundamental ecosystem transitions. However, it remains difficult to move beyond this broad concept and begin to answer specific questions, like how much climate change can be tolerated before complex ecological systems start to shift.

Mirroring developments in atmospheric science, progress in understanding the risks of ecosystem shifts under climate change and associated uncertainties, is likely to come from multi-model and multi-scenario ensemble assessment. This is a challenging task, but Lila Warszawski, from the Potsdam Institute for Climate Impact Research, and co-workers have taken an important step in this direction. Based on simulations from seven global vegetation models and a range of future climate scenarios, they use aggregate changes in ecosystems' biogeochemical state (for example, net primary productivity and vegetation carbon) as a proxy for the risk of ecosystem shifts under different levels of global warming.

Their results suggest that 5–19% of naturally vegetated land is at risk of severe ecosystem change under 2 °C of global warming, but with limited consensus across the models as to which regions face the highest risks.