A weakening of the global hydrological cycle between the 1950s and 1980s is attributable to increased atmospheric aerosols, reports a study published in Nature Climate Change this week. In a warming world, an increase in precipitation and river discharge could be expected, but this has not been observed. High levels of anthropogenic atmospheric particles account for this discrepancy until the 1980s, when increasing greenhouse gases lead to recovery of the cycle.
Peili Wu and colleagues analysed climate model simulations to discover the impact of climate change on the hydrological cycle. The observed trends in precipitation were found to be a result of the combined influence of two anthropogenic factors - atmospheric aerosols and greenhouse gas concentrations.
Increasing emissions with reductions in air pollution have strengthened the hydrological cycle in recent years, indicating that a further increase in precipitation may be expected if the current trend continues.