High sensitivity of future global warming to land carbon cycle processes

Booth, Ben B.B., Jones, Chris D., Collins, Mat, Totterdell, Ian J., Cox, Peter M., Sitch, Stephen, Huntingford, Chris, Betts, Richard A., Harris, Glen R., and Lloyd, Jon (2012) High sensitivity of future global warming to land carbon cycle processes. Environmental Research Letters, 7 (2). 024002. pp. 1-8.

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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 CO₂ 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 CO₂ 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 here to be key contributors to the magnitude of future change.

Item ID: 23647
Item Type: Article (Research - C1)
ISSN: 1748-9326
Keywords: carbon cycle; uncertainty; climate change; plant physiology
Date Deposited: 10 Oct 2012 05:27
FoR Codes: 04 EARTH SCIENCES > 0401 Atmospheric Sciences > 040104 Climate Change Processes @ 30%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 30%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 40%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960310 Global Effects of Climate Change and Variability (excl. Australia, New Zealand, Antarctica and the South Pacific) @ 100%
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