Solar activity and the westerlies dominate decadal hydroclimatic changes over arid Central Asia

Hydroclimatic changes over arid central Asia (ACA) are not fully understood, primarily due to the paucity of accurate, high-resolution climatic records. Here we reconstruct hydroclimatic changes over the past 160 years at Lake Karakul, Pamir Plateau (central Asia), using multiple, high-resolution (~0.8 yr) sedimentary proxies. We find that hydroclimatic changes at Lake Karakul are well correlated with meteorological records, the snow equilibrium line altitude (ELA), reconstructed regional precipitation, the westerly index, and total solar irradiance (TSI). We contend that solar activity and the westerlies were the dominant influences on ACA hydroclimatic variations during the period of record: (1) solar activity dominates regional temperature variations, precipitation/evaporation, and the advance/retreat of glaciers; (2) stronger westerly intensity (corresponding to higher westerly index and higher North Atlantic Oscillation (NAO) index) brings more water vapor from the west to ACA, and vice versa; and (3) the southerly migration of the westerly jet stream, which is closely related to lower TSI and temperatures, could favor more water vapor transported to ACA areas, and vice versa. We anticipate that continued global warming will result in more rapid glacial retreat, enhanced evaporation, lake area shrinkage, and deeper aridification over ACA.