A warm Atlantic linked to hot summers over Europe and US – University of Reading
01 July 2005
The Atlantic Ocean plays a much larger role in controlling summer climate in Europe and North America than previously thought, say Reading scientists in a paper published in the journal Science on 1 July 2005. The scientists, from the NCAS Centre for Global Atmospheric Modelling (CGAM) based at the University of Reading, have shown that over the last 100 years several swings in the temperature of the North Atlantic Ocean, each lasting decades at a time, have affected summer climate on both sides of the Atlantic. Lead author Dr Rowan Sutton said: "For the first time we have shown that changes in the Atlantic Ocean can actually drive the climate we experience either side of the Pond. By comparing observations with our results from state-of the-art climate models, we have shown that when the North Atlantic Ocean is warm, summers in the United States are warm and dry, and droughts more frequent. Conversely, when the ocean is cool, U.S. summers are cool and wet. The effects on European summers are more subtle but still important. "Finding this link is extremely important because it allows us to quantify the Atlantic's role in the climates of border countries. This information should improve our climate forecasts and help us to predict the effects on climate of future changes in the Atlantic Ocean circulation. "The swings in Atlantic Ocean temperature are related to variations in a huge overturning circulation known as the thermohaline circulation or Atlantic conveyor belt. Our research suggests that modest changes in this circulation have important effects on summers, not just winters as previously assumed. Bigger changes – in particular a slow down of the circulation – are expected in future in response to man-made global warming." The work has allowed the team to make tentative climate predictions for the coming years. Even without taking man-made global warming into account their computer models suggest both the U.S. and Europe could be in for more hot summers, and the U.S. may be facing more summer droughts. "But global warming is now a big additional factor," cautioned Dr Sutton. "And exactly how the effects will add up we don't yet know." End Notes to editors 1. The paper, 'Atlantic Ocean Forcing of North American and Western European Summer Climate' will be published in Science on 1 July 2005. A pdf of the paper is available on request from Science scipak@aaas.org, jlawrence@aaas.org; tel: 1-202-326-6440. 2. Dr Rowan Sutton is a Royal Society University Research Fellow based at the NCAS Centre for Global Atmospheric Modelling, at the University of Reading 3. More information: Dr Louisa Watts, NCAS Science Communications Manager Mobile: 07786 214886 E-mail: NCAScomms@nerc.ac.uk Natural Environment Research Council Press office: Marion O'Sullivan, tel: 01793 411727 or Owen Gaffney, tel: 01793 442629 or e-mail: pressoffice@nerc.ac.uk NERC Centres for Atmospheric Science Kathy Maskell (CGAM Science Communications) Contacts: 0118 378 8315 4. NERC is one of the UK's eight Research Councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind such as global warming, renewable energy and sustainable economic development. www.nerc.ac.uk The NERC Centres for Atmospheric Science (NCAS) carry out the UK's core academic atmospheric research programme, including climate variability and climate change. The Centre for Global Atmospheric Modelling is a component of NCAS and specialises in climate variability and climate change science. CGAM works closely with the Hadley Centre on issues related to climate change. Both NCAS Headquarters and CGAM are based in the Department of Meteorology at the University of Reading. http://ncas.nerc.ac.uk http://www.cgam.nerc.ac.uk http://www.met.reading.ac.uk 4. The University of Reading Department of Meteorology is a world-leading centre of excellence in the atmospheric sciences. With an RAE rating of 5*, it is the only UK Department to offer a full range of undergraduate and postgraduate courses in the atmospheric sciences. The Department has close research and training links with the European Centre for Medium Range Weather Forecasts and the UK Meteorological Office.