据悉，1959年至2011年间，大气CO2增长率对热带温度(γT)的敏感率几乎翻了一番，这一趋势与热带地区日益严重的干旱有关，此后γT开始下降。了解γT的这些变化是否反映碳循环中的作用力变化或内部气候变率，对于未来的气候预测至关重要。
研究人员表示，在初始条件受扰动的地球系统模型的模拟中，可能会出现加倍敏感性事件，可能用内部气候变率来解释。结果显示，加倍敏感性事件与少数但非常强烈的厄尔尼诺现象的发生有关，如1982/83和1997/98。
这些极端事件导致热带和温带生态系统同时释放碳，增加了全球陆地碳汇的变化及其对热带温度的表观敏感性。研究结果强调，敏感性加倍并不一定表明碳循环对气候变化的响应发生了变化。
附：英文原文
Title: Enhanced global carbon cycle sensitivity to tropical temperature linked to internal climate variability
Author: Na Li, Sebastian Sippel, Nora Linscheid, Christian Rdenbeck, Alexander J. Winkler, Markus Reichstein, Miguel D. Mahecha, Ana Bastos
Issue&Volume: 2024-09-25
Abstract: The sensitivity of atmospheric CO2 growth rate to tropical temperature (γT) has almost doubled between 1959 and 2011, a trend that has been linked to increasing drought in the tropics. However, γT has declined since then. Understanding whether these variations in γT reflect forced changes or internal climate variability in the carbon cycle is crucial for future climate projections. We show that doubling sensitivity events can arise in simulations by Earth system models with perturbed initial conditions but are likely explained by internal climate variability. We show that the doubling sensitivity event is associated with the occurrence of a few, but very strong, El Nino events, such as 1982/83 and 1997/98. Such extreme events result in concurrent carbon release by tropical and extratropical ecosystems, increasing the variance of the global land carbon sink and its apparent sensitivity to tropical temperature. Our results imply that the doubling sensitivity does not necessarily indicate a change in carbon cycle response to climate change.
DOI: adl6155
