High sensitivity of future global warming to land carbon cycle processes

作者：Ben Booth, Chris Jones, Matthew Collins, I. J. Totterdell, Peter M. Cox, Stephen Sitch, Chris Huntingford, Richard Betts, Glen Harris, Jon Lloyd · 发表于：Environmental Research Letters · 年份：2012 · DOI：10.1088/1748-9326/7/2/024002 · 被引用次数：354 · 研究领域：Atmospheric and Environmental Gas Dynamics、Climate variability and models、Plant Water Relations and Carbon Dynamics

Unknowns in future global warming are usually assumed to arise from uncertainties either in the amount of anthropogenic greenhouse gas emissions or in the sensitivity of the climate to changes in greenhouse gas concentrations. Characterizing the additional uncertainty in relating CO 2 emissions to atmospheric concentrations has relied on either a small number of complex models with diversity in process representations, or simple models. To date, these models indicate that the relevant carbon cycle uncertainties are smaller than the uncertainties in physical climate feedbacks and emissions. Here, for a single emissions scenario, we use a full coupled climate–carbon cycle model and a systematic method to explore uncertainties in the land carbon cycle feedback. We find a plausible range of climate–carbon cycle feedbacks significantly larger than previously estimated. Indeed the range of CO 2 concentrations arising from our single emissions scenario is greater than that previously estimated across the full range of IPCC SRES emissions scenarios with carbon cycle uncertainties ignored. The sensitivity of photosynthetic metabolism to temperature emerges as the most important uncertainty. This highlights an aspect of current land carbon modelling where there are open questions about the potential role of plant acclimation to increasing temperatures. There is an urgent need for better understanding of plant photosynthetic responses to high temperature, as these responses are shown he...