Climate Change in Israel: A Climatological-synoptic Study

Israel is situated on the edge of the desert belt, and displays extreme differences in climate between the north and the south of the country. In the north, Mediterranean conditions prevail while areas in the south are dry and arid. These climatic regions are characterized by sharp changes and fluctuations in weather patterns, including heat waves and dry spells which have severe impacts on the environment. Our ability to verify or disprove predicted trends based on accumulated data over past decades is therefore of great importance.

Our research is based on the analysis of climate trends, for example temperature, heat stress and rainfall fluctuations, from data collected over the past 35 years. A significant warming trend, in excess of the global rate, has been noted in the summer season, as well as an aggravation in heat waves and conditions of heat stress.

Regarding the rainfall regime, a general decrease in precipitation and a reduction in the number of rain days have been noted, though insignificant in most of the regions, presumably due to the large inter- and intra-annual variations characterizing this region. However, a lengthening of dry spells was found significant over most of the country.

Changes in the location of the aridity borders of 300 mm and 200 mm, critical for dry farming, are being studied. Results indicate that the size of the arid area has been expanding, especially over the last 20 years, at the expense of the Mediterranean temperate area. The contribution of changes in the occurrence of the regional synoptic systems to explain inter-annual variations and also long-term trends in temperature, heat stress and rainfall regimens is also being carefully studied. It was found that inter-decadal variations in the synoptic and large-scale factors explain considerable part of the rainfall and temperature variations.