Beyond 2°C: redefining dangerous climate change for physical systems
Beyond 2°C: redefining dangerous climate change for physical systems
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DOI：
10.1002/wcc.107
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发表时间：
2011-05
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影响因子：
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通讯作者：
T. Lenton
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文献类型：
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作者：
T. Lenton
大多数定义人类对气候系统的危险干扰水平的努力都是以全球年平均地表温度变化为框架的，比工业化前高2°C是最广泛接受的气候政策“目标”。然而，气候系统（可能有几个）中没有实际的大规模阈值（或“临界点”）与2°C全球变暖明显相关。在那些可能与全球气温变化有间接联系的危险水平中，危险水平必然是不精确的，而且各不相同，估计值从比工业化前高1.1 °C到更高。有些潜在阈值无法与全球温度变化有意义地联系起来，有些阈值对气候变化的速度很敏感，有些阈值对气候变化的空间梯度最敏感。在某些情况下，反射性（硫酸盐）气溶胶、吸收性（炭黑）气溶胶和土地利用的不均匀分布可能比全球混合温室气体的变化更危险。因此，《联合国气候变化框架公约》（《气候公约》）第2条关于稳定温室气体浓度（在一定时间范围内）的框架过于狭窄，无法防止某些类型的DAI。为了解决这个问题，提出了一个重新规划的政策目标：通过限制人为气溶胶的排放、土地利用模式以及短寿命和长寿命温室气体的浓度，来限制人为辐射强迫的总体幅度、变化率和空间梯度，以及由此产生的气候变化。WIREs Clim Change 2011 2 451-461 DOI：10.1002/wcc.107
Most efforts to define a level of dangerous anthropogenic interference (DAI) with the climate system are framed in terms of global annual mean surface temperature change, with 2°C above preindustrial being the most widely accepted climate policy ‘target’. Yet, no actual large‐scale threshold (or ‘tipping point’) in the climate system (of which there are probably several) has been clearly linked to 2°C global warming. Of those that can be indirectly linked to global temperature change, the dangerous levels are necessarily imprecise and vary, with estimates ranging from ∼1°C above preindustrial upwards. Some potential thresholds cannot be meaningfully linked to global temperature change, others are sensitive to rates of climate change, and some are most sensitive to spatial gradients of climate change. In some cases, the heterogeneous distributions of reflective (sulfate) aerosols, absorbing (black carbon) aerosols, and land use could be more dangerous than changes in globally well‐mixed greenhouse gases. Hence, the framing of Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC), in terms of stabilization of greenhouse gas concentrations (within a time frame), is too narrow to prevent some types of DAI. To address this, a reframed policy objective is proposed; to limit the overall magnitude, rate of change, and spatial gradients of anthropogenic radiative forcing, and resultant climate change, through restriction of emissions of anthropogenic aerosols, patterns of land use, and concentrations of short‐lived, as well as long‐lived, greenhouse gases. WIREs Clim Change 2011 2 451–461 DOI: 10.1002/wcc.107