Lake water changes in response to climate change in northern China: Simulations and uncertainty analysis

摘要

Catchment water balance and lake water decline in arid-semiarid areas of China are very sensitive to direct and indirect changes in precipitation and temperature, as evident in written records of the last 50 years and in paleoclimatic records of the past 30,000 years. IPCC-based climate scenarios and outputs of a number of GCM experiments have provided an important basis to configure future climate and to estimate the probability of lake level changes in the next 50 years. However, there are many uncertainties in applying the GCM outputs to regional catchments to evaluate responses at a smaller scale. Monte Carlo probability analysis provides a powerful tool for estimating probability, and this technique was applied to generate scenarios of lake-level responses to future climate change in four arid-semiarid lakes of China. Simulations of Monte Carlo model show that lake level would increase in all sites with precipitation increases, but with temperature increases in Hulun and Aibi basins and with temperature decreases in Qinghai and Daihai basins. With about a 95% chance of a temperature increase in the coming 50 years, the probability of lake water response is about ±50% in Qinghai Basin, +25 ～ -70% in Daihai Basin, +30% ～ -20% in Hulun Basin and ±20% in Aibi Basin. Although the predicted future changes of precipitation do not exceed those of the past 30,000 years as estimated from paleorecords, about a 40% annual precipitation change in recent years has caused large lake water decreases and serious drought in the arid basins. Thus, the lower estimate of 20 ～ 40% decreases of lake level, as estimated with Monte Carlo simulations, seem very probable within the next few decades.