14 DAY TRIAL // If you still do not believe that the Antarctic ice will melt, and your beach house will be flooded, read this: last winter has been the warmest in Europe in over 700 years! A similarly hot winter could have occurred in 1289, as found by a Swiss team led by J?rg Luterbacher at the University of Bern.
The earliest European climate measurements and temperature records come from the UK, starting with 1659. Behind this, historical temperatures must be deduced from contemporary documents and diaries.
"People in churches, or doctors, wrote diaries, and usually they also included information about weather and climate. Climate historians can use and interpret this information and translate it into a temperature value," explains Luterbacher, who collaborated with climate historians to see past and recent temperatures.
The 2006-2007 temperatures have been the hottest in 500 years, that's for sure. And a similar phenomenon seems to have occurred in 1289, based on what people in western and central Europe witnessing it wrote about the extremely unusual events. "Documents report for instance that strawberries were eaten at Christmas, and the [vineyards] produced leaves, stock and even blossoms in the middle of January, and in Vienna fruit trees were flowering like in May," Luterbacher told New Scientist. "This was really extreme, so maybe it can be compared to today in western and central Europe."
The last winter also induced unusual natural events, like hazel trees and snowdrops in Germany flowering a month earlier than the usual time in the spring of 2007. In 2006, Swiss horse chestnut trees blossomed twice (they usually blossom once yearly). In the UK, the warmer time induced twice instead of one spring fructification in mushrooms. "The 1289 temperatures may have been caused by a large volcanic eruption in the tropics, but there has been no such event in the past few years.", said Luterbacher.
The Swiss team thinks the recent warm autumn and winter is the cause for the warm air moving up from the Atlantic off the coast of North Africa. "Future studies will use computer models to determine how likely it is that such warm temperatures would have been seen without human greenhouse-gas emissions.", Luterbacher told New Scientist.
In 2004, research found it "very likely that human influence has at least doubled the risk" of extreme weather events, like the 2003 European heat wave, which killed 35,000 people, mainly in the Mediterranean area.