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
