Laboratoire Atmosphère Milieux Observations Spatiales LATMOS-IPSL, UMR CNRS 8190, Sorbonne Université, UVSQ, Paris, France.
Scuola Universitaria Superiore IUSS, Pavia, Italia.
Sci Rep. 2020 May 6;10(1):7670. doi: 10.1038/s41598-020-63782-2.
The time of emergence (TOE) of climate change is defined as the time when a new climate state emerges from a prior one. TOE assessment is particularly relevant in West Africa, a region highly threatened by climate change and urgently needing trustworthy climate predictions. In this paper, the TOE of precipitation change in West Africa is assessed for the first time, by analyzing 6 precipitation metrics (cumulated precipitation, number of wet and very wet days, onset and length of the rainy season) computed from the output of 29 state-of-the-art climate models. In West Sahel, climate conditions characterized by reduced occurrence of wet days are likely to emerge before 2036, leading to the possible emergence of a dryer climate in 2028-2052. In East Sahel, a wetter precipitation regime characterized by increased occurrence of very wet days is likely to emerge before 2054. Results do not provide a clear indication about a possible climate shift in the onset and length of the rainy season. Although uncertainty in climate model future projections still limits the robust determination of TOE locally, this study provides reliable time constraints to the expected climate shift in West Africa at the sub-regional scale, supporting adaptation measures to the future change in the precipitation regime.
气候变化的出现时间 (TOE) 定义为新的气候状态从先前的气候状态中出现的时间。TOE 评估在西非尤为重要，该地区受气候变化威胁严重，迫切需要可靠的气候预测。在本文中，首次通过分析从 29 个先进气候模型的输出计算得出的 6 个降水指标（累积降水、湿润和极湿润天数、雨季开始和持续时间）来评估西非降水变化的出现时间。在西非萨赫勒地区，湿润天数减少的气候条件可能会在 2036 年之前出现，导致 2028-2052 年可能出现更干燥的气候。在东萨赫勒地区，极湿润天数增加的湿润降水模式可能会在 2054 年之前出现。结果并没有明确表明雨季开始和持续时间可能会发生气候变化。尽管气候模型未来预测的不确定性仍然限制了局部 TOE 的可靠确定，但本研究为西非次区域预期的气候变化提供了可靠的时间限制，支持适应未来降水模式变化的措施。
