Changing weather patterns
Forecasting future weather patterns is not an exact science but our best understanding of the potential impact of climate change on south east water resources is based on the latest UK Climate Projections 2009.
While there will always be assumptions and uncertainties in any work of this kind, these Projections represent strong and credible science and help us understand the risks that lie ahead.
The Projections show – through high, medium and low greenhouse gas emissions scenarios – how our future climate could change dramatically should the world fail to reduce its emissions. Based on a ‘medium emissions’ pathway, which according to the Climate Change Committee is the one that the world is most closely following, we could see average summer temperature increases in the South East of 3.9ºC within our children’s lifetimes (by the 2080s). At the same time, we could see a 22% decrease in average summer rainfall in the South East. This will have an impact on our demands for water in the future and the amounts of water that are present in the natural environment.
Pressure on supplies
Prolonged periods of hotter weather would have a serious impact on our water resources, leading to more evaporation from our reservoirs and rivers, just as demand increases in homes, businesses and from the agricultural sector. At the same time, the more intense rainfall anticipated would result in surface flooding and more pollutants running off into our rivers and streams. Water quality could suffer and aquifers may not be recharged as efficiently as they are by gentler, more persistent and steady rainfall.
The current projections also suggest drought conditions are likely to be more common. The worst case scenario in a Met Office study suggested that we might have ten times as many significant droughts by 2100 with droughts like that of 1976 occurring on average every ten years. While water companies are better prepared for such droughts than they were 35 years ago, we cannot be confident that our infrastructure would stand up to the more unusual conditions we might see under a changing climate, such as several consecutive and very dry years.
A stressed environment
And it’s not just a question of supply and demand. Hotter weather is likely to put more stress on our water environment. Lower water levels in our rivers and lakes would reduce their capacity to dilute pollutants, and worsen water quality, as well as reducing their ability to sustain wildlife and important species such as salmon and trout. Poor water quality also needs more intensive treatment to make it fit for public consumption, raising costs to customers and increasing energy use and carbon emissions.