The use of aridity index to assess implications of climatic change for land cover in Turkey

Authors: DERYA ÖNDER, MEHMET AYDIN, SÜHA BERBEROĞLU, SERMET ÖNDER, TOMOHISA YANO

Abstract: This study was carried out to determine the impacts of climate change on aridity and land cover in Turkey. Data for future (2070s) climate change, according to present conditions (1990s), were estimated from the prediction results of a regional climate model (RCM). The RCM, which was developed in Japan, is based on the MRI model. The potential impacts of climate change were estimated according to the A2 scenario of Special Report on Emissions Scenarios (SRES). Aridity index, the ratio of precipitation to potential evapotranspiration, was computed by using measured data for the present condition and estimated data by the RCM for the future years. Changes in aridity were evaluated by comparing the current and future index values. Aridity variables were interpolated to determine the spatial distribution by means of geostatistical methods. Land cover was modelled and mapped by using the present and future aridity index data. In the southern regions of Turkey, especially along Mediterranean coasts, projected precipitation for 2070s will be 29.6% less than the present. On the contrary, an increase (by 22.0%) in precipitation was projected along the coast of Black Sea. The model predicted that the temperature might increase by 2.8-5.5 °C in the different regions of the country. This increase in temperature could result in higher evaporative demand of the atmosphere in the future (on the average 18.4 and 22.2% in the Mediterranean and Black Sea coastal regions, respectively and 17.8% in the whole country). Thus, an increase in aridity was foreseen for the whole Turkey except the north-eastern part. A conversion of deciduous broadleaf forest to evergreen needle-leaf forest is predicted in the northern coastal areas when we compare the future land cover with the present situation. The mixed forest vegetation could spread in the interior parts of East Anatolia and the north-western part of the country in the future.

Keywords: Aridity, climate change, land cover, monitoring, Turkey

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