Climate Indices as indicators of desertification in Argentina

DOYLE, MOIRA E.; GISELLE MARINCOVICH

Congreso; IAPSO-IAMAS-IAGA Joint Assembly; 2017

One of the UNCCD priorities is the necessity to create indices to help identify potential desertification risk. Root causes of desertification include climatic fluctuation and adaptation of drylands ecosystems due to limited fresh water supplies, and erratic rainfall leading to seasonal variability, annual and decadal fluctuations that may cause droughts and flooding events. Drylands cover a large extension of Argentina and 75% of the country is affected by a desertification process. Dry periods have increased in the arid diagonal crossing the country from northwest to southeast and extreme precipitation events have become more frequent and intense to the east. These droughts could further intensify in 21st century under scenarios of increased evapotranspiration, decreased precipitation or a combination of both. These factors indicate there is a high probability of an acceleration of processes leading to desertification. Precipitation seasonality and the Aridity Index are among the climatic indicators used to monitor desertification. CMIP5 global climate model results for historical 1900-2010 time period are used to validate the ability of models to represent the present distribution of drylands and potential areas to be affected by desertification processes. The Precipitation Seasonality Index and the Aridity Index are calculated for 20 models and CRU data used as observations to validate the models. Decadal variations and differences between the beginning and the end of the 20th century are studied to understand the degree and extent of advance of desertification due to climate factors in the country and which is the contribution of climate change, in particular how changes in temperature have contributed and to what point changes in precipitation modify the desertification process.