The impact of climate change on Quaternary glaciers of Gharaghom Basin in Iran

Abstract

This research has mapped the quaternary equilibrium line altitude (ELA) using Whrite's and Porter's methods to reconstruct past and present temperatures using a regression model and to detect the potential impact of climate change on glaciers using an arti cial neural network in the Gharaghom basin located in northeastern Iran. De ning a regression model between temperature and altitude based on available observation data and reconstructed data indicated that the present temperature lapse rate of -0.41°C would occur for every hundred meters of increasing altitude in stations. The reconstruction of the past temperature of the Pleistocene revealed an increase of about 10.36-10.5 ˚C for the mean annual temperature of the current temperature in the basin. The recent ELA rises from the Pleistocene 2236 m and 2200 m a.s.l according to Whrite and Porter's methods respectively. So, considering the present temperature lapse rate and the highest altitude of 3271m in the basin, the maximum Pleistocene ELA depression would be about 800m due to modern temperature increase of 10.36-10.5°C compared to the past Pleistocene temperature. Based on the neural network prediction model, linear growth in temperature would occur for the next three decades in the Gharaghom basin. Based on trend analysis, the minimum temperature has been much more affected than the maximum temperature, so global warming has caused an increase in the monthly minimum and maximum temperature in most seasons in different parts of the Basin. The average temperature rise of 0.19°C for future decades would consequently affect the water resources in the basin.