Abstract
The most severe effects of global warning will be related to the frequency and severity of extreme events. We provide an analysis of projections of temperature and related extreme events for Africa based on a large ensemble of Regional Climate Models from the COordinated Regional climate Downscaling EXperiment (CORDEX). Results are presented not only by means of widely used indices but also with a recently developed Heat Wave Magnitude Index-daily (HWMId), which takes into account both heat wave duration and intensity. Results show that under RCP8.5, warming of more than 3.5 °C is projected in JFM over most of the continent, whereas in JAS temperatures over large part of Northern Africa, the Sahara and the Arabian peninsula are projected to increase up to 6 °C. Large increase in in the number of warm days (Tx90p) is found over sub equatorial Africa, with values up to more than 90 % in JAS, and more than 80 % in JFM over e.g., the gulf of Guinea, Central African Republic, South Sudan and Ethiopia. Changes in Tn90p (warm nights) are usually larger, with some models projecting Tn90p reaching 95 % starting from around 2060 even under RCP4.5 over the Gulf of Guinea and the Sahel. Results also show that the total length of heat spells projected to occur normally (i.e. once every 2 years) under RCP8.5 may be longer than those occurring once every 30 years under the lower emission scenario. By employing the recently developed HWMId index, it is possible to investigate the relationship between heat wave length ad intensity; in particular it is shown that very intense heat waves such as that occurring over the Horn of Africa may have values of HWMId larger than that of longer, but relatively weak, heat waves over West Africa.
Highlights
It is well known that the most severe effects of global warming will be related to a change in the mean climate, but especially to an increase in frequency and intensity of extreme events, such as floods, droughts and heat waves
For the first time to our knowledge, we provide an analysis of projections of temperature and related extreme events for Africa based on the results of a large ensemble of CORDEX Regional Climate Models (RCMs)
In this work we have analyzed the projections of temperature and related extreme events for Africa based on the results of a large ensemble of CORDEX RCMs
Summary
It is well known that the most severe effects of global warming will be related to a change in the mean climate, but especially to an increase in frequency and intensity of extreme events, such as floods, droughts and heat waves. The occurrence and intensity of extreme events, defined by IPCC (2012) as a value of a weather or climate variable above or below a threshold value near the upper or lower ends of the range of observed values, are expected to change, as reported by e.g. Tebaldi et al (2006), Russo and Sterl (2011), Orlowsky and Seneviratne (2011), and Sillmann et al (2013b) Due to their low spatial resolution, GCMs are not able to resolve small-scale processes that are influenced by e.g. topographical details, coastlines, and land-surface heterogeneities.
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