Natural variability, radiative forcing and climate response in the recent hiatus reconciled
Natural variability, radiative forcing and climate response in the recent hiatus reconciled
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DOI：
10.1038/ngeo2228
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发表时间：
2014-09-01
影响因子：
18.3
通讯作者：
Knutti, Reto
中科院分区：
文献类型：
--
作者：
Huber, Markus;Knutti, Reto
在过去15年左右的时间里，全球平均地表变暖程度低于前几十年，也低于大多数气候模型的模拟结果（1）。自然变率（2-4）、辐射强迫减少（5-7）、对大气二氧化碳浓度的变暖反应较小（8，9）和观测覆盖偏差（10）已被确定为潜在原因。然而，对所谓“变暖间断”的解释仍然不完整，对长期气温预测的影响也不清楚。在这里，我们估计与厄尔尼诺/南方涛动（ENSO）的非强迫气候模式控制模拟相匹配的观测到的气候变率段的内部变率的贡献。我们发现，ENSO变化类似于1997年或1998年至2012年之间的变化，导致约-0.06 ℃的冷却趋势。此外，从观测中得到的最新太阳和平流层气溶胶强迫解释了类似幅度（-0.07摄氏度）的冷却趋势。考虑到这些调整后的趋势，我们发现，一个复杂性降低的气候模型，其瞬态气候响应约为1.8摄氏度，与过去15年的温度记录一致，耦合模型相互比较项目第5阶段（CMIP 5）中模型的集合平均值也是如此。我们的结论是，有系统的高估的温度响应增加大气CO2浓度的CMIP 5合奏的证据很少。
Global mean surface warming over the past 15 years or so has been less than in earlier decades and than simulated by most climate models(1). Natural variability(2-4), a reduced radiative forcing(5-7), a smaller warming response to atmospheric carbon dioxide concentrations(8,9) and coverage bias in the observations(10) have been identified as potential causes. However, the explanations of the so-called 'warming hiatus' remain fragmented and the implications for long-term temperature projections are unclear. Here we estimate the contribution of internal variability associated with the El Nino/Southern Oscillation (ENSO) using segments of unforced climate model control simulations that match the observed climate variability. We find that ENSO variability analogous to that between 1997 or 1998 and 2012 leads to a cooling trend of about -0.06 degrees C. In addition, updated solar and stratospheric aerosol forcings from observations explain a cooling trend of similar magnitude (-0.07 degrees C). Accounting for these adjusted trends we show that a climate model of reduced complexity with a transient climate response of about 1.8 degrees C is consistent with the temperature record of the past 15 years, as is the ensemble mean of the models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). We conclude that there is little evidence for a systematic overestimation of the temperature response to increasing atmospheric CO2 concentrations in the CMIP5 ensemble.