Tackling extreme droughts
With droughts expected to become more severe, we are working on securing a reliable water supply in a changing UK climate.
Across the world, work on climate change has focused minds on the risks and impacts of drought on water supply. We face significant but uncertain challenges from population growth and climate change, and there is an increasing emphasis on ensuring we are sufficiently resilient to droughts beyond those experienced in the recent past. In 2013, research suggested that 39 per cent of the world’s population was then at risk of suffering from water scarcity during droughts, and that this could increase to 53 per cent by 2080 if the global temperature rises by 2ºC.
HR Wallingford and other organisations are trying to understand the impacts of more severe droughts on the availability of public and private water supplies. In the UK, water companies typically used to plan to meet supply needs for droughts of a similar severity to the worst case in the past, but our work considers what would happen if they were even more extreme.
It is impossible to predict when the next drought will occur, or how severe it will be. In addition to hotter, drier summers, the latest climate projections by the UK Climate Projections 2018 (UKCP18) suggest the potential for:
- longer recession periods because of lower autumn rainfall;
- an increased likelihood of successive dry winters; and
- severe and sustained droughts over large parts of the UK.
This means that it is critical that planners can understand and communicate the resilience of our water supply under a range of conditions beyond those experienced in the recent past. The figure below shows an example drought event from one of the Met Office’s latest climate model runs, with a drought severity indicator used to relate rainfall totals to typical conditions.