Mohamed Aoubouazza, Rachid Rajel and Rachid Essafi.
This work is devoted to examine trends and extreme climate variability observed over the past five decades in Morocco, and future projections of these trends for the coming five decades. It also aims to assess the potential impact of these trends on water resources as well as threats to agricultural production. Five weather stations representing the type different types of climate in Morocco who has been the subject of statistical analysis of their extreme temperature indices (minimum and maximum) and their daily rainfall, during the time span 1960 to 2004. These indices of extreme temperatures (TX90eme, TN90eme, TX10eme, TN10eme, IVF, IFC) and precipitation (R10: number of days or total precipitation above 10 mm), were recorded through the four seasons of the year. Overall, the curves of change of temperature indices show a significant upward trend of hot days and a significant downward trend in the case of cold days, reflecting a slight warming of the climate of Morocco. Regarding the precipitation, in general, the curves of rainfall indices showed a downward trend but not to a significant extent, except for the “Oujda” station, where a significant declining tendency was noted. In order to understand future trends and forecast future projections, software MAGICC/ CENGEN was applied to average emission scenario P50 powered variable of average temperatures and precipitation for the period 1981 to 2004. The projection of these meteorological parameters to 2050 confirms a clear trend toward warming (1.7°C and 2.6 °C) for the 1st parameter while a significant reduction is registered in the case of the 2nd parameter (15-22% in the northeast, 9 and 16% in the south), reflecting a transition of climate to the semi-arid in the north of Morocco. Due to climate warming and decreased precipitation, the overall intake between 1940 and 2005 for all dams in Morocco recorded a deficit of 20%. This deficit is estimated for 2050 to be between 13.6 to 21.3 % compared to the present situation in the simulated results of climate models used in this study for three large dams. It is forecasted that the northern region of Morocco would be most affected by climate change resulting into a significant reduction in irrigated area (4200 to 6500 ha) and, consequently, a substantial drop in agricultural production, thus threatening food security for the inhabitants of these regions.