The widespread drying of soils, due to higher evaporation rates due to global warming, is shrinking water supplies to the point that drought-like conditions may become the norm in many parts of Australia.

At a news conference held in Sydney, Prof Ashish Sharma of the University of New South Wales – who led the most exhaustive global analysis of rainfall and rivers to date – said that climate models had predicted that, for every 1˚C of warming, the warmer atmosphere would be able to store 7% more moisture. The models also expected that this would lead to a roughly 7% rise in flooding per degree rise in temperature.

However, the team’s measurements of actual rainfall and river flows indicates that, when it comes to frequent floods – those smaller floods essential for refilling dams and water catchments – the reverse is happening. Frequent floods are decreasing at roughly 10-15% for each degree rise in temperature.

The team believe this is due to the drying of soils worldwide, driven by global warming, which is causing the drier soils to absorb more of rain, leaving less to go into water catchments.  This has grave implications, as it indicates the rivers and reservoirs upon which we depend are already drying – and this effect will only worsen as the atmosphere heats up.

A full copy of the report is available at