Near-term tropical cyclone risk and coupled Earth system model biases
Near-term tropical cyclone risk and coupled Earth system model biases
复制标题
近期热带气旋风险和耦合地球系统模型偏差
DOI：
10.1073/pnas.2209631120
复制
发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Seager, Richard
中科院分区：
文献类型：
--
作者：
Sobel, Adam H.;Lee, Chia-Ying;Bowen, Steven G.;Camargo, Suzana J.;Cane, Mark A.;Clement, Amy;Fosu, Boniface;Hart, Megan;Reed, Kevin A.;Seager, Richard
目前的大多数气候模型预测，在温室气体引起的变暖的情况下，赤道太平洋将在今后几十年内演变成更类似厄尔尼诺的状态，纬向海面温度梯度降低，大气步行者环流减弱。然而，过去50年的观察显示了相反的趋势，朝着更像拉尼娜的状态发展。最近的研究提供的证据表明，这种差异不能被视为由于内部变异，而是模型错误地模拟了赤道太平洋对温室气体变暖的反应。这意味着对区域热带气旋活动的预测也可能不正确，甚至在变化方向上也可能不正确，其方式可以通过类比历史上的厄尔尼诺和拉尼娜事件来理解：例如，北太平洋热带气旋预测过于活跃，北大西洋热带气旋预测不够活跃。其他危险，包括严重的对流风暴和干旱，也将被错误地预测。虽然可以说这些误差是暂时的，因此模型对温室气体的反应在平衡时可能是正确的，但这种暂时的反应与今后几十年的气候适应有关。考虑到了解近期气候风险的区域模式的紧迫性，最好能制定出代表更广泛的未来热带太平洋变暖趋势的预测，包括最近历史趋势持续的一些预测，即使目前无法使用现有的耦合地球系统模型进行预测。
Most current climate models predict that the equatorial Pacific will evolve under greenhouse gas–induced warming to a more El Niño-like state over the next several decades, with a reduced zonal sea surface temperature gradient and weakened atmospheric Walker circulation. Yet, observations over the last 50 y show the opposite trend, toward a more La Niña-like state. Recent research provides evidence that the discrepancy cannot be dismissed as due to internal variability but rather that the models are incorrectly simulating the equatorial Pacific response to greenhouse gas warming. This implies that projections of regional tropical cyclone activity may be incorrect as well, perhaps even in the direction of change, in ways that can be understood by analogy to historical El Niño and La Niña events: North Pacific tropical cyclone projections will be too active, North Atlantic ones not active enough, for example. Other perils, including severe convective storms and droughts, will also be projected erroneously. While it can be argued that these errors are transient, such that the models’ responses to greenhouse gases may be correct in equilibrium, the transient response is relevant for climate adaptation in the next several decades. Given the urgency of understanding regional patterns of climate risk in the near term, it would be desirable to develop projections that represent a broader range of possible future tropical Pacific warming scenarios—including some in which recent historical trends continue—even if such projections cannot currently be produced using existing coupled earth system models.