Robust direct effect of carbon dioxide on tropical circulation and regional precipitation
Robust direct effect of carbon dioxide on tropical circulation and regional precipitation
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DOI：
10.1038/ngeo1799
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发表时间：
2013-06-01
影响因子：
18.3
通讯作者：
Denvil, Sebastien
中科院分区：
文献类型：
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作者：
Bony, Sandrine;Bellon, Gilles;Denvil, Sebastien
预测热带降雨对气候变化的响应仍然是一个挑战（1）。预计二氧化碳浓度的上升将通过全球平均温度和大气中水蒸气含量的增加而影响水文循环（2-4）。然而，区域降水变化也密切依赖于大气环流，预计在更温暖的世界中会减弱（4-6）。在这里，我们通过分析来自多个最先进的气候模型和一个业务数值天气预报模型的一套模拟结果，评估了大气二氧化碳浓度上升对热带环流和降水的影响。在人类继续不减地使用化石燃料的情况下，预计到21世纪末，热带环流变化的一半左右，以及区域降水变化的很大一部分，与全球地表变暖无关。相反，这些强劲的环流和降水变化是与大气二氧化碳水平较高相关的大气净辐射冷却较弱的结果，这影响了大气垂直运动的强度。这意味着，旨在减少全球变暖而不从大气中去除二氧化碳的地球工程计划将无法完全缓解热带地区的降水变化。可能有助于限制降雨量预测的策略提出了建议。
Predicting the response of tropical rainfall to climate change remains a challenge(1). Rising concentrations of carbon dioxide are expected to affect the hydrological cycle through increases in global mean temperature and the water vapour content of the atmosphere(2-4). However, regional precipitation changes also closely depend on the atmospheric circulation, which is expected to weaken in a warmer world(4-6). Here, we assess the effect of a rise in atmospheric carbon dioxide concentrations on tropical circulation and precipitation by analysing results from a suite of simulations from multiple state-of-the-art climate models, and an operational numerical weather prediction model. In a scenario in which humans continue to use fossil fuels unabated, about half the tropical circulation change projected by the end of the twenty-first century, and consequently a large fraction of the regional precipitation change, is independent of global surfacewarming. Instead, these robust circulation and precipitation changes are a consequence of the weaker net radiative cooling of the atmosphere associated with higher atmospheric carbon dioxide levels, which affects the strength of atmospheric vertical motions. This implies that geo-engineering schemes aimed at reducing global warming without removing carbon dioxide from the atmosphere would fail to fully mitigate precipitation changes in the tropics. Strategies that may help constrain rainfall projections are suggested.