High sensitivity of future global warming to land carbon cycle processes
High sensitivity of future global warming to land carbon cycle processes
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DOI：
10.1088/1748-9326/7/2/024002
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发表时间：
2012-04-01
影响因子：
6.7
通讯作者：
Lloyd, Jon
中科院分区：
文献类型：
--
作者：
Booth, Ben B. B.;Jones, Chris D.;Lloyd, Jon
未来全球变暖的未知数通常被认为是由于人为温室气体排放量或气候对温室气体浓度变化的敏感性的不确定性造成的。将二氧化碳排放量与大气浓度联系起来的额外不确定性的表征，要么依赖于少数具有过程表示多样性的复杂模型，要么依赖于简单的模型。到目前为止，这些模型表明，相关的碳循环不确定性小于物理气候反馈和排放的不确定性。在这里，对于单一排放情景，我们使用一个完全耦合的气候-碳循环模型和一个系统的方法来探索陆地碳循环反馈中的不确定性。我们发现，气候-碳循环反馈的合理范围比之前估计的要大得多。事实上，我们的单一排放情景产生的二氧化碳浓度范围比之前估计的在整个IPCC SRES排放情景中的范围更大，忽略了碳循环的不确定性。光合作用代谢对温度的敏感性成为最重要的不确定性。这突显了当前陆地碳模拟的一个方面，其中关于植物适应气温上升的潜在作用存在悬而未决的问题。迫切需要更好地了解植物对高温的光合作用反应，因为这些反应被证明是未来变化幅度的关键贡献者。
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.