Search for: All records

Lake Issyk-Kul, located in the glacial mountain ranges in mid-latitude arid Central Asia (ACA), is one of the world’s largest lakes. ACA is projected to face future changes in water supply due to rising temperatures and increased precipitation. These changes pose significant economic and environmental threats, particularly in regions with high population growth. Despite its importance, the mid-latitude continental region has many unknown questions surrounding the history of the westerlies, leaving gaps in our understanding of past climate dynamics. This research examines the paleoclimate of Lake Issyk-Kul from approximately 14,000 years ago to the present, utilizing a suite of organic biomarkers to reconstruct temperature, hydroclimate, and vegetation. We measured several organic geochemical proxies including lacustrine alkenones (U index) and isoprenoid and hydroxylated glycerol dialkyl glycerol tetraethers (GDGTs; TEX86 and RIOH proxies). Additionally, the distribution and isotopic composition of plant waxes (n-alkanes) are analyzed to infer changes in surrounding vegetation and moisture sources. Preliminary results indicate significant and abrupt climate shifts in the Issyk-Kul region during key periods such as the Bølling-Allerød and Younger Dryas. We compare biomarker records from sites on the western and eastern sides of the lake to understand regional variations in climate response in a large lake system that spans a precipitation gradient. These findings enhance our understanding of the sensitivity of Issyk-Kul in regional and global climate regimes, contributing to more accurate predictions of future conditions in ACA. 

Abstract Changes in ice‐sheet size impact atmospheric circulation, a phenomenon documented by models but constrained by few paleoclimate records. We present sub‐centennial‐scale records of summer temperature and summer precipitation hydrogen isotope ratios (δ²H) spanning 12–7 ka from a lake on Baffin Island. In a transient model simulation, winds in this region were controlled by the relative strength of the high‐pressure systems and associated anticyclonic circulation over the retreating Greenland and Laurentide ice sheets. The correlation between summer temperature and precipitation δ²H proxy records changed from negative to positive at 9.8 ka. This correlation structure indicates a shift from alternating local and remote moisture, governed by the two ice‐sheet high‐pressure systems, to only remote moisture after 9.8 ka, governed by the strong Greenland high‐pressure system after the Laurentide Ice Sheet retreated. Such rapid atmospheric circulation changes may also occur in response to future, gradual ice‐sheet retreat.