Sunny skies or stormy weather - monks wrote it in their diaries 500 years ago

Published on 17/01/2011 17:39

ANCIENT weather records, including details gleaned from monks' diaries, are helping Scottish scientists work out how and why European climates have changed over the past 500 years.

Researchers found the historic data, from the likes of weather station archives and harvest records, closely matched modern computer simulations of climate patterns over the past five centuries.

They say the fact the computer models were on target for the past suggests future predictions will be accurate, and forecast that greenhouse gas emissions will shape the climate in future in a "significant and visible" way.

The study was carried out by Edinburgh University in collaboration with the Justus-Liebig University of Giessen in Germany, and the Universities of Bern and Madrid. Published in Nature Geoscience, it was supported by the Natural Environment Research Council, the US National Science foundation and the European Union.

Professor Gabi Hegerl, of Edinburgh's School of GeoSciences, who led the study, said the archives revealed a considerable amount of interesting information, particularly relating to the last 300 years.

She said: "Five hundred years ago, the records were quite sparse, but there is a lot of data going back to the 19th century and quite a lot of data from the 17th and 18th centuries.

"Around 1675, it gets quite sparse. Before that, we're working from monks' diaries and harvest records and all kinds of indirect evidence about whether they experienced warm or cold summers and winters."

The computer simulations took account of influences on the weather, such as volcanic activity, variations in the Sun's brightness, and - more recently -an increase in greenhouse gases.

Among the events studied were the catastrophic eruptions of Mount Tambora and the volcanic island of Krakatoa in Indonesia. The Tambora event in 1815 killed at least 71,000 people and created global climate anomalies, including the "year without a summer" in 1816 because of the effect on North American and European weather.

The Krakatoa explosion in 1883 killed 40,000 people and also led to climate changes.

Prof Hegerl said ice cores taken from Greenland and the Antarctic showed evidence of fallout from the eruptions which were backed up by historic data.

The study suggests greenhouse gas emissions will play an important role in shaping future European climate.

Prof Hegerl said current human behaviour was "very likely going to shape the climate in a significant and visible way".She added: "Our work shows that even small changes in factors outside the climate system have a significant effect.

"The climate models seem to be working quite well for the past, so we should expect that they will do well for the future."