TRENDS IN EXTREME TEMPERATURE AND PRECIPITATION OVER WEST AFRICA USING ENSEMBLE OF COMMUNITY EARTH SYSTEM MODEL

Abstract

This study aims at examining the trends of extreme temperature and precipitation under a changing climate using Global Climate model projections over West Africa. The study analyzed trends in daily maximum and minimum temperatures and precipitation using climate indices from the Expert Team on Climate Change Detection and Indices (ETCCDI) over the Agroecological zones in West Africa using data from Community Earth System Model (CESM) from 1990 – 2099. Extreme value distribution was also applied to a set of maxima using block maxima approach to examine the return period of extreme precipitation and temperature events in the near and far future. Data was grouped into climate periods which are; the present climate (1990-2019), near future climate (2030-2059) and far future climate (2070-2099). Regionally averaged temperature extremes show warming trends over the entire West Africa in the present climate. Temperature of hottest day and hottest night showed increase of 0.011°C/decade and 0.009°C/decade respectively. Extremely cold days and nights have decreased while hot days and nights have increased which is a sign that the climate warmed in present climate. In the near future climate, intensity of hot extremes reduced in the Guinea and Sudan Savannah while the entire West Africa and Sahel show increase. Generally, intensity of hottest days reduced and coldest days increased in the far future climate. This imply that the severity of these extremes change in the far future climate. Ecologically/regionally averaged indices trends suggest West Africa will warm in the near future climate except for Guinea savannah and Sudan savannah which is cooling. Through all climate periods, the number of dry periods of more than 5 days (CDD) in Guinea savannah decreased. Very heavy precipitation days and heavy precipitation days increased all over the present climate but Consecutive wet days reduced suggesting more short rainfall with high intensity for Sudan and Sahel savannah. Generally, Guinea Savannah had a decline in dry season length and increase in Precipitation days, Very heavy precipitation days and Consecutive Wet days for all climate