Drying soils threaten water supplies

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 anews conference held in Sydney yesterday, Prof Ashish Sharma of the at 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.

Below please find links to an audio recording of the press conference, plus a transcript and photos, as well as a link to the full media release.

  • AUDIO RECORDING of the news conference held at UNSW Sydney on 13 December 2018; speakers are Prof Ashish Sharma and Prof Mark Hoffman, Dean of Engineering at UNSW.
  • TRANSCRIPT of the news conference.
  • PHOTOS of the news conference.
  • MEDIA RELEASE: A copy of the full media release that accompanied the news conference.
  • VIDEO: ProfAshish Sharma and Prof Mark Hoffman summarising the research and calling for an international discussion on its implications.
  • PHOTOS: Ashish Sharma and Dr Conrad Wasko at UNSW, and inside the labs at UNSW’s Water Research Centre. Also, aerial views of the Snowy Mountain Scheme and California State Water Project.
  • SCIENTIFIC PAPERS: For the full text of the four papers on which this research is based; inNature Geoscience, Geophysical Research Letters, Scientific Reports and Water Resources Research.
/Public Release.