Is climate change affecting our summer weather?
In Britain the weather is always a talking point, but a succession of heatwaves in Europe this summer have brought climate into the conversation too.
Hot and dry conditions have been the big story this summer. Heatwaves have been hitting the headlines since late June, with high-profile wildfires and deaths across the Northern Hemisphere. In the UK, July was named the third hottest on record and temperatures have reached above 33℃. Scientists from the National Centre for Atmospheric Science have explained how the day-to-day weather we’re experiencing this year is linked to climate change.
This summer’s heatwave was associated with an unusually persistent high pressure system above the UK, and it is natural to wonder if climate change has had a part to play in this. Ed Hawkins, Professor of Climate Science at the University of Reading, has answered this question by explaining that in a world where our atmosphere is getting warmer due to climate change, we should expect that particular weather events will also be warmer.
Areas in the South East UK experienced over 50 days without rain, which transformed the UK’s vegetation from green to brown in a month. Professor Rowan Sutton, Director of Climate at NCAS, said “there should be little surprise that we’re seeing heat waves and associated impacts across many parts of the world, given that climate science has predicted an increase in the severity and frequency of heatwaves for decades.” The world has warmed by about 1 degree celsius since the nineteenth century with greater warming over land, and recent weather events (including both high temperatures and lightning storms) are influenced by this long-term change in our climate.
Scientists are beginning to better understand the links between extreme weather and climate change and think it is very likely that human influence has contributed to the global changes in the frequency of temperature extremes since the mid-twentieth century. Professor Len Shaffrey, a Senior NCAS Research Scientist based at the University of Reading, says that recent studies have assessed that climate change has increased the probability of extremes such as the 2017 European ‘Lucifer’ heatwave by a factor of at least 4.
However, climate change is just one factor affecting our current weather. Len recently summarised a number of reasons why this summer has been so hot and dry in an article for The Conversation, outlining the impact that climate change, North Atlantic temperatures, and general weather patterns could all have had on this summer’s heatwave. Should these weather patterns continue as they are, we might expect this summer to be as hot and dry as the extreme summer of 1976.
One example of the impact of recent prolonged hot and dry weather is the moorland fires in Greater Manchester. NCAS Professor James Lee, based at the University of York, took to the skies in the FAAM aircraft last month to measure emissions from these fires and sample the pollution being emitted. James noted that “more hot dry weather in the UK is likely to lead to more moorland fires in the UK and worldwide, so it is important that we begin to understand the effects on global greenhouse gas and air pollution problems."
Scientists are virtually certain that there will be more frequent hot temperature extremes over land areas as global mean temperatures increase. So as a result of climate change, heatwaves are likely to be more frequent, and last for longer.