Attribution Science and UK Storms and Flooding

While it is widely known that it is hard to assign individual extreme weather events to climate change, advances in attribution science including a new project will help us to zero in on the causes of specific storms. Improved attribution science including spatial resolution climate models will enable us to get a better grasp of how individual extreme weather events are linked to global warming.

Attribution studies have shown that anthropogenic climate change has significantly increased the chances of the catastrophic temperatures seen in Europe in 2003, which brought many thousands of heat-related deaths. Likewise, the record Australian temperatures of 2013, which brought devastating forest fires and the destruction of many homes, have become substantially more likely due to human influence on climate.

Dr Peter Stott, head of the Climate Monitoring and Attribution team at the UK Met Office acknowledges that studies have shown the human influence on climate, he also warns against over assigning such phenomenon. While he accepts that greenhouse gas emissions have been the dominant cause of global warming, he cautions that at present it is still hard to attribute individual extreme weather events to climate change. He goes on to say that unusual extremes have always happened and are sometimes due to natural variability and not climate change.

Stott suggests that natural variability may explain the recent run of wet summers in the UK dating back to 2007. He further explains that mis-attribution of extreme weather to climate change can easily lead to bad policy making.

It is clear that global warming has led to an increase in moisture in the atmosphere and roughly four percent more moisture over the oceans than in the 1970s. This has increased the likelihood of more intense rainfall. Attribution science`s study of wet and stormy weather in the UK has produced mixed results. The consecutive series of storms that have slammed into Britain this winter are due to an anomalous jet stream that has brought a sequence of intense storms on a more southerly track than usual.

While there is much that we do not know, a new European project may yield significant scientific dividends. The project is called EUCLEIA and it is led by the Met Office. It is developing a system that will provide reliable and user-relevant attribution assessments of floods, droughts, heatwaves, cold spells and storm surges in real time.