Lake-sediment records of recent climate variability in north-west China's drylands.

Abstract

The recent anthropogenic changes of the global climate system are likely to have an impact on future changes in the East Asian monsoon system. Research predicting these changes is of great importance, as they could affect the lives of millions across China. Palaeoclimatic studies are required in order to allow for such predictions. The Badain Jaran Desert, in north-west China, is a suitable site in this region for gathering (palaeo)limnological data from which reconstructions of past effective moisture in the region could be made, as it sits at the landward margin of monsoonal activity, and contains numerous lakes. In this study, sediment cores and modern limnological data were gathered from these lakes, as both are necessary for palaeolimnological reconstruction. The modern limnological data showed that the lakes can be divided into a northern and a south-eastern suite that are geochemically, isotopically and physically distinct. They are all evaporatively enriched, but in the south-eastern suite this is controlled by individual basin morphology, whereas the lakes in the northern suite have all reached their maximum heavy isotope enrichment value. An isotope mass balance model shows that \sigma{^1^8}O values are primarily controlled by relative humidity, and secondarily by \sigma{^1^8}O values of input water. Four short sediment cores from the south-eastern suite were dated using the AD 1963 {^1^3^7}Cs peak. Comparisons of multiproxy analysis of these cores to regional palaeoclimate records shows that evaporative enrichment has been caused by changes in humidity. The records also suggest that periods of increased monsoonal activity correspond to a decrease in effective moisture across the region. Since 1970 the aridity trend that the lakes have shown is probably caused by anthropogenic increases in global temperature, indicating that further increases may cause the lakes to dry out completely.

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This paper was published in Research Papers in Economics.

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