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The Arctic Amplification Debate

机译：北极放大辩论

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Rises in surface air temperature (SAT) in response to increasing concentrations of greenhouse gases (GHGs) are expected to be amplified in northern high latitudes, with warming most pronounced over the Arctic Ocean owing to the loss of sea ice. Observations document recent warming, but an enhanced Arctic Ocean signal is not readily evident. This disparity, combined with varying model projections of SAT change, and large variability in observed SAT over the 20th century, may lead one to question the concept of Arctic amplification. Disparity is greatly reduced, however, if one compares observed trajectories to near-future simulations (2010-2029), rather than to the doubled-CO sub(2) or late 21st century conditions that are typically cited. These near-future simulations document a preconditioning phase of Arctic amplification, characterized by the initial retreat and thinning of sea ice, with imprints of low-frequency variability. Observations show these same basic features, but with SATs over the Arctic Ocean still largely constrained by the insulating effects of the ice cover and thermal inertia of the upper ocean. Given the general consistency with model projections, we are likely near the threshold when absorption of solar radiation during summer limits ice growth the following autumn and winter, initiating a feedback leading to a substantial increase in Arctic Ocean SATs.
机译：预计北半球高纬度地区由于温室气体（GHGs）浓度增加而引起的地表空气温度（SAT）升高，由于海冰的损失，北冰洋的升温最为明显。观测记录了最近的变暖，但北冰洋信号增强的趋势并不明显。这种差异，再加上不同的SAT变化模型预测，以及20世纪观测到的SAT的巨大变化，可能使人们对北极放大的概念提出质疑。但是，如果将观察到的轨迹与近乎未来的模拟（2010-2029）进行比较，而不是将CO-sub（2）翻倍或通常引用的21世纪末期进行比较，则差异会大大减小。这些接近未来的模拟记录了北极放大作用的预处理阶段，其特征是海冰的初始退缩和变薄，并带有低频变化的印记。观测结果显示出这些相同的基本特征，但北冰洋上空的SAT在很大程度上仍受冰盖的绝热作用和上层海洋的热惯性的约束。考虑到与模型预测的总体一致性，当夏季吸收太阳辐射限制了秋季和冬季之后的冰的生长时，我们很可能接近阈值，从而引发反馈，导致北冰洋SAT大幅增加。

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