Monks' diaries shed light on climate forecasts
A team of EU-funded scientists has used monks' diaries and other historical records to confirm the accuracy of computer-based climate simulations. The findings, published online in the journal Nature Genetics, should help researchers deliver more accurate climate change estimates, particularly at the regional and seasonal scales. EU support for the work came from two projects: CIRCE ('Climate change and impact research: the Mediterranean environment') and ACQWA ('Assessment of climatic change and impacts on the quantity and quality of water'). In this study, scientists used 3 climate models to simulate changes in the climate over the past 500 years. They compared the results of the climate models with historical sources such as weather station archives, harvest records, and the diaries of monks. The historical records matched the simulations well. The scientists were particularly interested in the influence on the weather, at both the seasonal and regional scales, of factors external to the climate system, such as volcanic activity, changes in the Sun's temperature, and a rise in greenhouse gas emissions from human activities. As the scientists point out, 'it is the regional and seasonal expression of climate change that determines the effect of greenhouse warming on ecosystems and society.' While the influence of greenhouse gas emissions on Europe's climate is recognised for the 20th century, some scientists have suggested that the influence of external factors in earlier centuries is 'negligible'. The study revealed that in fact external factors have had a major influence on Europe's weather throughout the past five centuries. This suggests that our current greenhouse gas emissions are likely to play a significant role in shaping Europe's climate in the future. 'Our work shows that external influences on the weather are important, and that even small changes in factors outside the climate system have a significant effect,' explained the lead author of the paper, Professor Gabi Hegerl of the School of Geosciences at the University of Edinburgh in the UK. 'These findings are significant because we are seeing the impact of these factors at a regional level.' Volcanoes have a particularly noticeable impact on the climate in the short term; summers following an eruption tend to be significantly cooler than the norm, while winters are warmer. However, volcanoes do not appear to exert much influence on spring and autumn temperatures. The influence of external factors on the climate is particularly strong in winter and spring, where they account for an estimated 75% of the observed winter warming since the late 17th century. 'This winter warming is largely attributable to greenhouse-gas forcing,' the researchers note. The scientists conclude: 'Here we use reconstructions of seasonal European land temperature and simulations with three global climate models to show that external influences on climate - such as the concentrations of stratospheric volcanic aerosols or greenhouse gases, other anthropogenic effects and possibly changes in total solar irradiance - have had a discernible influence on European temperatures throughout the past five centuries.' In addition to researchers from the University of Edinburgh, the study included scientists at Justus-Liebig University of Giessen in Germany, the Universidad Complutense Madrid in Spain, and the University of Bern in Switzerland. The CIRCE project is funded under the 'Sustainable development, global change and ecosystems' Thematic area of the Sixth Framework Programme (FP6) to the tune of EUR 10 million. The project, which began in 2007 and is scheduled to draw to a close this year, brings together researchers in over 60 organisations from Europe, the Middle East and Africa. The 5-year ACQWA project, which got underway in 2008, has been allocated EUR 6.5 million of EU research funding from the Environment Theme of the Seventh Framework Programme (FP7). Its 35 partners come from Europe and South America.For more information, please visit: University of Edinburgh:http://www.ed.ac.uk Nature Geoscience:http://www.nature.com/naturegeoscienceCIRCE project:http://www.circeproject.euACQWA project:http://www.acqwa.ch
Countries
Switzerland, Germany, Spain, United Kingdom