A 1000 year history of atmospheric sulfate concentrations in southern Asia as recorded by a Himalayan ice core

A sulfate record covering the period A.D. 1000-1997 from the Dasuopu glacier in the Himalayas reveals that this site is sensitive to anthropogenic activity originating in southern Asia. Prior to 1870 atmospheric sulfate concentrations were relatively low and constant, but thereafter concentrations have increased and since 1930 the rate of increase has accelerated rapidly. This accelerating trend in sulfate deposition is paralleled by growing SO2 emissions over southern Asia resulting from the increased energy demand. The concentration of sulfate deposited in the last 50 years exceeds that for any prior 50-year period in the last millennium. Unlike the Greenland ice core-derived sulfate concentrations that have declined since the 1970s, sulfate concentrations deposited on the Himalayan ice fields continue to increase, having nearly doubled since 1970. This reflects regional differences between Europe and Asia in source strength and transport pathways for atmospheric sulfate, as well as differing degrees of environmental regulation.