Romanzini-Bezerra Grasiele, Maycock Amanda C
School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
Nat Commun. 2024 Aug 3;15(1):6590. doi: 10.1038/s41467-024-50648-8.
Deep, rapid and sustained reductions in greenhouse gas emissions are required to meet the 2015 Paris Agreement climate target. If the world strengthens efforts toward near-term decarbonisation and undertakes major societal transformation, this will be met with requests from policymakers and the public for evidence that our actions are working and there are demonstrable effects on the climate system. Global surface temperature exhibits large internal variability on interannual to decadal timescales, meaning a reduction in the magnitude of surface warming would not be robustly attributable to climate mitigation for some time. In contrast, global stratospheric temperature trends have much higher signal-to-noise ratios and could offer an early indication of the effects of climate mitigation. Here we examine projected near-term global temperature trends at the surface and in the stratosphere using large ensemble climate models following three future emission scenarios. Under rapid, deep emission cuts following SSP1-1.9, modelled middle and upper stratospheric cooling trends show a detectable weakening within 5 years compared to a scenario approximately representing current climate commitments (SSP2-4.5). Therefore, stratospheric temperature trends could serve as an early indicator to policymakers and the public that climate mitigation is taking effect.
为实现2015年《巴黎协定》的气候目标，需要深度、快速且持续地减少温室气体排放。如果世界加强近期脱碳努力并进行重大社会转型，政策制定者和公众将要求提供证据，证明我们的行动正在发挥作用，并且对气候系统有明显影响。全球地表温度在年际到年代际时间尺度上表现出很大的内部变率，这意味着在一段时间内，地表变暖幅度的降低不能确凿地归因于气候缓解措施。相比之下，全球平流层温度趋势的信噪比要高得多，并且可以为气候缓解措施的效果提供早期指示。在此，我们使用大型集合气候模型，根据三种未来排放情景，研究了预计的近期全球地表和平流层温度趋势。在遵循SSP1-1.9的快速、深度减排情况下，与大致代表当前气候承诺的情景（SSP2-4.5）相比，模拟的平流层中层和上层冷却趋势在5年内显示出可检测到的减弱。因此，平流层温度趋势可以作为一个早期指标，向政策制定者和公众表明气候缓解措施正在生效。
