From the hurricane that smashed into New York in 1938 to the impact of the Krakatoa eruption of 1883, the late 19th and 20th centuries are rich with examples of extreme weather. Now an international team of climatologists have created a comprehensive reanalysis of all global weather events from 1871 to the present day, and from the Earth's surface to the jet stream level. Among those researchers was Stefan Brönnimann, a member of the Oeschger Centre. The results of the 20th Century Reanalysis Project, just published in the Quarterly Journal of the Royal Meteorological Society, not only allow researchers to understand the long-term impact of extreme weather, but provides key historical comparisons for our own changing climate. "Producing this huge dataset required an international effort to collate historical observations and recordings from sources as diverse as 19th century sea captains, turn of the century explorers and medical doctors, all pieced together using some of the world's most powerful supercomputers at the US Department of Energy's National Energy Research Scientific Computing Center in California and the Oak Ridge Leadership Computing Facility in Tennessee," says Gil Compo at the National Oceanic and Atmospheric Administration (NOAA), the leader of the project. By using historical climate data to understand current weather patterns the international team, which includes 27 scientists, are building on the work of their meteorological forebears such as the U.S. Historical Weather Map Series produced by the U.S. Weather Bureau to better understand weather events preceding World War II. However, the 20th Century Reanalysis Project is the first project of its kind to span a full century. "The resulting weather maps, called reanalyses, provide a much longer record of past weather variability than is currently available to compare present and projected weather variability in a warming climate. They also provide valuable insight into extreme weather and climate events that were historically important", says Stefan Brönnimann at the Oeschger Centre. The picture shows an example of extreme events covered by the new dataset. A storm on 28th December 1879 made collapse the bridge over the Firth-of-Tay in Scotland.
