To many, London means the Thames, Big Ben, and rain. But London shouldn’t be known for rain, as it receives less rainfall than Dallas, Rome, or Sydney. Looking to the future, Water UK suggests that London will face more severe, frequent droughts.
The city already experienced a major drought in the winter of 2011-12. Facing shortages, London’s water utilities asked for a drought permit to allow them to increase supply. If it wasn’t for the extremely wet spring and summer to follow, heavy restrictions on demand would have been necessary. As droughts are likely to occur more frequently and as precipitation will become more uncertain, London cannot expect to always be saved by rain.
Thames Water gets 30% of its water from aquifers and 70% from the River Thames and the River Lee. Rainfall influences river flows and groundwater levels. According to Professor Adrian Butler of Imperial College London, the issue is that London relies on winter rainfall to meet demand for the entire year. “If you have a succession of dry winters, you are facing a catastrophe in summer.” Due to climate change summers are likely to become drier and winters will be wetter. The increased rainfall in the winter will likely be experienced as extreme downpour which is hard to capture and save for drought. Thames Water anticipates that summers will be 3C warmer and 18% drier on average by 2050. In the United Kingdom, climate change will decrease available water by 7-17 percent.
A lower and uncertain supply is not London’s only issue. The population of London is expected to increase by 100,000 each year and is likely to be above 13 million in 2050. The growing population in combination with household growth is predicted to increase the water demand in London and the Thames Valley by 46-90%, depending on the conservation scenario. Besides greater population and household sizes, hotter and drier summers also raise water demand. The 2018 heatwave lead to a 30 percent increase in household water demand. The figure below compares London’s increase in demand with its decrease in supply, showing how their difference — a gap indicating shortage — will increase over time.
Bottom-line: London is not the rainy city we imagine. Due to climate change, the city is likely to experience droughts more frequently and more severely, resulting in a decrease in water supply. In combination with an increase in demand due to population and household growth and climate change, London’s risk of water shortages is increasing.
* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂