Near-term regional climate change in East Africa

Abstract

In the coming few decades, projected increases in global temperature and humidity are generally expected to exacerbate human exposure to climate extremes (e.g., humid-heat and rainfall extremes). Despite the growing risk of humid-heat stress (measured by wet-bulb temperature), it has received less attention in East Africa, where arid and semi-arid climatic conditions prevail. Moreover, no consensus has yet been reached across models regarding future changes in rainfall over this region. Here, we screen Global Climate Models (GCMs) from CMIP5 and CMIP6 and use, for boundary conditions, simulations from only those GCMs that simulate successfully recent climatic trends. Based on these GCMs and Regional Climate Model (RCM) simulations, we project that annual mean temperature is likely to rise by 2 ℃ toward midcentury (2021–2050) ​at a faster rate than the global average (about 1.5 ℃), under the RCP8.5 and SSP5-8.5 scenarios, associated with more frequent and severe climate extremes. In particular, low-lying regions in East Africa will be vulnerable to severe heat stress, with an extreme wet-bulb temperature approaching or exceeding the US National Weather Service’s extreme danger threshold of 31 ℃. On the other hand, population centers in the highlands of Ethiopia will receive significantly more precipitation during the autumn season and will see more extreme rainfall events, with implications for flooding and agriculture. The robustness of these results across all GCM and RCM simulations, and for both of CMIP5 and CMIP6 frameworks (CMIP: Coupled Model Inter-comparison Project) supports the reliability of these future projections. Our simulations of near-term climate change impacts are designed to inform the development of sound adaptation strategies for the region.

Trends and Variability in Temperature and Related Extreme Indices in Rwanda during the Past Four Decades

“…The increase in temperature and drying conditions have resulted in increased drought in many places of the Earth [7,[118][119][120][121][122][123][124]. During the last years, East Africa has experienced more recurrent, intense, and longer-lasting drought events [11,[13][14][15][16][17]119], causing damage to infrastructure, water scarcity, drying of crops, famine, and food insecurity, leading to the frequent migrations of populations [17][18][19][20][21]. Recent observations have indicated that the eastern and southeastern parts of Rwanda have been experiencing rainfall deficits, resulting in severe droughts alternated by prolonged moderated drought.…”

“…Despite the recent experience that the East African region has known and knows today, the impacts of climate change have not spared Rwanda [14][15][16]. The country has committed to undertake adaptation and mitigation measures to the greatest extent possible for vulnerable communities.…”

“…Observations in this region indicate a rapid warming of about 1.9 • C as the maximum temperature and 1.2 • C as the minimum temperature during the period 1979 to 2010 [11] and a mean temperature increase of 2 • C from 1963 to 2012 [12]. During the last years, East Africa has been subject to more recurrent, intense, and prolonged droughts [11,[13][14][15][16][17], causing frequent migrations of populations triggered by water scarcity, the drying of crops, famine, and food insecurity [17][18][19][20][21]. Climate change is likely to affect health in East Africa, resulting in a number of direct and indirect impacts, Malaria being among the greatest threats to human health [22].…”

Implications of WRF model resolutions on resolving rainfall variability with topography over East Africa

“…Both GCMs and regional climate models (RCMs) suffer from systematic biases which could be attributed to complex topography, weaknesses in parameterization schemes, coarse spatial resolutions, and atmosphere-biosphere process transitions over large water bodies (Allen et al, 2002;Cardell et al, 2019;Ayugi et al, 2020;Choi et al, 2023). East Africa, a region marked with complex topography such as mountains, the Great Rift Valley (GRV), and major inland water bodies, is a case where systematic biases present a challenge in the generation of skilful climate services for operational applications.…”

Examining climate trends and patterns and their implications for agricultural productivity in Bagamoyo District, Tanzania

“…In SSA, for instance, climate models project drier states in the southern region and highly variable and reduced rainfall in West Africa (Kotir, 2011). However, these models lack consensus regarding future precipitation changes in the East Africa (EA) region (Choi et al, 2023). The EA region comprises the greater horn of Africa, which in the recent past has witnessed frequent droughts and persistent food shortages (Nicholson, 2014).…”