The impact of Earth system feedbacks on carbon budgets and climate response
The impact of Earth system feedbacks on carbon budgets and climate response
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地球系统反馈对碳预算和气候响应的影响
DOI：
10.1098/rsta.2017.0263
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
D. Bernie
中科院分区：
文献类型：
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作者：
J. Lowe;D. Bernie
一些研究审查了允许的全球累积碳预算的规模，该预算与将21世纪世纪全球平均气温相对于工业化前水平的上升限制在2°C以下和1.5°C以下相一致。这些对累积排放量的估计有许多不确定性，包括与气候敏感性和全球碳循环有关的不确定性。虽然气专委第五次评估报告载有关于一系列地球系统反馈的信息，如永久冻土融化释放的碳或气候变化导致湿地产生的甲烷，但许多这些地球系统过程对允许的碳预算的影响仍有待量化。在这里，我们进行了初步估计，以表明来自典型的未代表的地球系统过程的综合影响可能对将变暖限制在比工业化前水平高1.5°C或2°C的可验证性很重要。影响的大小范围高达约350 GtCO2预算减少1.5°C升温极限和约500 GtCO2减少实现升温极限2°C。对于两个变暖极限，额外地球系统强迫的中位数估计分别为100 GtCO2和150 GtCO2。我们的估计相当于目前几年的人为二氧化碳排放量。除了可能减少允许的全球碳预算外，额外的反馈还提前了特定排放途径可能超过给定变暖阈值的日期。本文是《巴黎协定：了解世界变暖比工业化前水平高1.5°C的物理和社会挑战》主题的一部分。
A number of studies have examined the size of the allowable global cumulative carbon budget compatible with limiting twenty-first century global average temperature rise to below 2°C and below 1.5°C relative to pre-industrial levels. These estimates of cumulative emissions have a number of uncertainties including those associated with the climate sensitivity and the global carbon cycle. Although the IPCC fifth assessment report contained information on a range of Earth system feedbacks, such as carbon released by thawing of permafrost or methane production by wetlands as a result of climate change, the impact of many of these Earth system processes on the allowable carbon budgets remains to be quantified. Here, we make initial estimates to show that the combined impact from typically unrepresented Earth system processes may be important for the achievability of limiting warming to 1.5°C or 2°C above pre-industrial levels. The size of the effects range up to around a 350 GtCO2 budget reduction for a 1.5°C warming limit and around a 500 GtCO2 reduction for achieving a warming limit of 2°C. Median estimates for the extra Earth system forcing lead to around 100 GtCO2 and 150 GtCO2, respectively, for the two warming limits. Our estimates are equivalent to several years of anthropogenic carbon dioxide emissions at present rates. In addition to the likely reduction of the allowable global carbon budgets, the extra feedbacks also bring forward the date at which a given warming threshold is likely to be exceeded for a particular emission pathway. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels’.