Abstract:
We examine the impact of +1.5 ◦C and +2 ◦C global warming levels above pre-industrial levels on
consecutive dry days (CDD) and consecutive wet days (CWD), two key indicators for extreme
precipitation and seasonal drought. This is done using climate projections from a multi-model
ensemble of 25 regional climate model (RCM) simulations. The RCMs take boundary conditions
from ten global climate models (GCMs) under the RCP8.5 scenario. We define CDD as the
maximum number of consecutive days with rainfall amount less than 1 mm and CWD as the
maximum number of consecutive days with rainfall amount more than 1 mm. The differences in
model representations of the change in CDD and CWD, at 1.5 ◦C and 2 ◦C global warming, and
based on the control period 1971−2000 are reported. The models agree on a noticeable response to
both 1.5 ◦C and 2 ◦C warming for each index. Enhanced warming results in a reduction in mean
rainfall across the region. More than 80% of ensemble members agree that CDD will increase over the
Guinea Coast, in tandem with a projected decrease in CWD at both 1.5 ◦C and 2 ◦C global warming
levels. These projected changes may influence already fragile ecosystems and agriculture in the region,
both of which are strongly affected by mean rainfall and the length of wet and dry periods.
