导致21世纪极端气候的气候变化在世界各地的特大城市中更为明显,尤其是在西非。大阿克拉地区是西非人口最多的地区之一。因此,该地区变得更容易受到洪水等极端气候的影响,热浪,和干旱。该研究采用了耦合模型比较项目6模型,模拟了1979年至2059年间西非共享社会经济途径情景(SSP)下的气候极端指数,以大阿克拉地区为例。该研究观察到历史时期的干旱普遍较弱,预计在大阿克拉地区的SSP585下尤其会加剧。例如,在SSP下,连续干燥天数(CDD)呈增加趋势。同样,西非CDD的总体预测趋势表明,未来干旱将更加频繁和更长。洪水指数显示,在该地区的SSP下,极端降水事件的强度和持续时间激增。例如,在SSP下,R99pTOT和Rx5天预计将显着增加,在SSP245,SSP370和SSP585下将加剧。西非也有类似的趋势,尤其是在几内亚海岸.该研究预计,大阿克拉地区的热浪指数将逐渐上升。在历史时期以及在SSP下,特别是在阿克拉和特马等城市中心,变暖和降温指数分别显示出增加和减少的趋势。预计大多数西非国家将观察到更频繁的温暖日夜,而寒冷的夜晚和白天变得不那么频繁。未来极端气候指数的预期影响对水构成潜在威胁,食物,和能源系统,并引发大阿克拉地区的经常性洪水和干旱。该研究的结果预计将为气候政策和《巴黎协定》的国家自主贡献提供信息,并解决西非的可持续发展目标11(可持续城市)和13(气候行动)。
Climate change leading to Climate extremes in the twenty-first century is more evident in megacities across the world, especially in West Africa. The Greater Accra region is one of the most populated regions in West Africa. As a result, the region has become more susceptible to climate extremes such as floods, heatwaves, and droughts. The study employed the Coupled Model Intercomparison Project 6 models in simulating climate extreme indices under the Shared Socioeconomic Pathway scenarios (SSPs) over West Africa between 1979 and 2059 as exemplified by the Greater Accra region. The study observed a generally weak drought in the historical period and expected to intensify especially under SSP585 in Greater Accra. For instance, continuous dry days (CDD) reveal an increasing trend under the SSPs. Similarly, the overall projected trend of CDD over West Africa reveals an increase signifying a more frequent and longer drought in the future. The flood indices revealed a surge in the intensity and duration of extreme precipitation events under the SSPs in the region. For instance, R99pTOT and Rx5days are expected to significantly increase under the SSPs with intensification under the SSP245, SSP370, and SSP585. A similar trend has been projected across West Africa, especially along the Guinean coast. The study foresees a gradual and intensifying rise in heatwave indices over the Greater Accra region. The warming and cooling indices reveal an increasing and decreasing trend respectively in the historical period as well as under the SSPs particularly within urban centers like Accra and Tema. Most West African countries are projected to observe more frequent warm days and nights with cold nights and days becoming less frequent. Expected effects of future climate extreme indices pose potential threats to the water, food, and energy systems as well as trigger recurrent floods and droughts over Greater Accra. The findings of the study are expected to inform climate policies and the nationally determined contribution of the Paris Agreement as well as address the sustainable development goal 11 (Sustainable cities) and 13 (Climate action) in West Africa.