Through modeling and international exchange, the Abdus Salam International Centre for Theoretical Physicsis fostering advanced climate research in countries where scientific resources are often scarce. P opulations in economically developing nations (EDNs) depend extensively on climate for their welfare (e.g., agriculture, water resources, power generation, industry) and likewise are vulnerable to variability in the climate system, whether due to anthropogenic forcing or natural processes. Furthermore, changes in atmospheric composition (e.g., greenhouse gases and aerosols) and land cover are likely to significantly alter regional climates (Nakicenovic et al. 2001), thereby affecting local socioeconomic development and livelihoods of EDN populations. Therefore, the evaluation of climate change and variability at seasonal-to-multidecadal time scales is of great benefit to these regions.Climate models, both global and regional, are the primary tools that aid in our understanding of the many processes that govern the climate system. In the past, a lack of computational resources has hindered the use of climate models by EDN scientists. However, in the last decade the computing power of the common desktop personal computer (PC) has dramatically increased •

We find that elevated greenhouse gas concentrations dramatically increase heat stress risk in the Mediterranean region, with the occurrence of hot extremes increasing by 200 to 500% throughout the region. This heat stress intensification is due to preferential warming of the hot tail of the daily temperature distribution, with 95th percentile maximum and minimum temperature magnitude increasing more than 75th percentile magnitude. This preferential warming of the hot tail is dictated in large part by a surface moisture feedback, with areas of greatest warm‐season drying showing the greatest increases in hot temperature extremes. Fine‐scale topographic and humidity effects help to further dictate the spatial variability of the heat stress response, with increases in dangerous Heat Index magnified in coastal areas. Further, emissions deceleration substantially mitigates heat stress intensification throughout the Mediterranean region, implying that emissions reductions could reduce the risk of increased heat stress in the coming decades.

[1] Results are presented from high resolution climate change simulations over the Mediterranean region using the ICTP Regional Climate Model, RegCM3. Two sets of multi-decadal simulations are performed at 20-km grid spacing for present day and future climate (IPCC A2 scenario). We analyze changes in precipitation mean and extremes and find that the change signal shows seasonally dependent fine scale structure in response to the topographic forcing and changes in circulation, especially over the Alpine region and the Iberian, Italian and Hellenic peninsulas. In winter, the mean precipitation change is positive in the Northern Mediterranean regions and negative in the Southern Mediterranean, while precipitation in the other seasons mostly decreases (especially in summer), except over some localized areas. Changes in extreme precipitation events and dry spells suggest not only shifts, but also a broadening, of the precipitation distribution, with an increased probability of occurrence of events conducive to both floods and droughts. Citation: Gao, X., J. S. Pal, and F. Giorgi (2006), Projected changes in mean and extreme precipitation over the Mediterranean region from a high resolution double nested RCM simulation, Geophys. Res. Lett., 33, L03706,