Climate change in drylands of the eastern mediterranean: From assessment methods to adaptation strategies

Abstract

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change projects that the drylands around the Mediterranean are likely to be severely affected by climate change. Most Global Circulation Models (GCMs) predict for the Mediterranean region in the coming decades a continuation of a trend of precipitation decline, derived for the period 1901–2007 from the Full Data Reanalysis Product Version 4 of the Global Precipitation Climatology Centre, of 0–3 mm year−1 in the annual precipitation. Thus climate change is likely to hit the Mediterranean zone twice, by higher temperatures, raising the risk of heat stress to the traditional crops of the region, and by lower precipitation and increased risk of drought. Using a case study from the eastern Mediterranean, a GIS-based method is presented for generating high-resolution maps that overcome the restrictions on use for planning imposed by the coarse resolution of the GCM predictions. The downscaled climate change projections for the near future, obtained from these maps, are the starting point for exploring how the time-honored coping mechanisms of the region’s diverse agricultural systems could be adjusted in order to deal with the additional stresses to be imposed by climate change. The key to adaptation to climate change will be in reviewing how these agricultural systems have been coping in the past and present, and in revisiting and fine-tuning the recommended management practices established after decades of dryland agricultural research. The main adaptation strategies anticipated under climate change are geographical shifts in the agricultural systems, better climate-proofing of rainfed systems, making irrigated systems more efficient and in expanding the role of intermediate rainfed-irrigated systems. With the expected increase of aridity in the Mediterranean Zone, shifts are likely in the geographical location of the agricultural systems: those that currently occur within a particular aridity class will tend to occupy the agroecological niche of those systems currently in a more humid zone, and will themselves be substituted by systems currently in a more arid climate. The expected increase in high-intensity precipitation events calls for improved water conservation leading to higher soil moisture and better control of runoff and evaporation losses. Whereas in the past there was a clear differentiation between rainfed and irrigated systems, it is also likely that climate change will promote the spread of hybrid systems, which make alternative use of rainfall and irrigation water, in order to cope with increasing water shortage while maintaining a high productivity. As climate change is likely to be accompanied by more severe intra-seasonal drought, more salvation may come from incorporating drought tolerance in traditional crops through breeding or genetic manipulation and trading off productivity against security. If markets can be created, there may also be potential for introducing drought-tolerant ‘new’ crops that have shown high potential under research conditions. In conclusion, location-specific combinations of these key adaptation strategies should allow the agricultural systems of the region to cope with climate change, at least in the near future, although some systems may come under more stress than others.