Impact of the desiccation of the Aral Sea on summertime surface air temperatures

• Aral Sea surface area has decreased by more than 80% since the 1970s.
• Mesoscale atmospheric model simulations show a strong local and regional warming due to the shrinking of the lake.
• Near-surface air temperature observations are consistent with simulations.
• Large-scale climate variability and land use change also contribute to the warming.

The Aral Sea located in Central Asia has undergone drastic changes in the last 50 years. This study quantitatively estimates the change in lake surface area since the 1970s and investigates how this change can affect local and regional near-surface air temperatures during the summer. LANDSAT satellite imagery shows more than 80% reduction in lake surface area since the 1970s. Simulations with the Weather Research and Forecasting (WRF) regional climate model show that this change in the lake surface can lead to a statistically significant warming of more than 6 °C in 2 m air temperatures over the dry lake bed and a significant warming signal of up to 1 °C covering an area up to 200 km around the original lake boundary, especially to the south. Observations in this region are sparse but still warming trends consistent with the simulations are seen in 2 m air temperatures from the Global Historical Climatology Network dataset. Atmospheric reanalysis and land cover data suggest that large-scale climate variability and land use change in the Amu Darya and Syr Darya basins contribute to the regional warming trends. Improvements in data and modeling capability are required to study the effects on diurnal and seasonal temperature cycle.