Austrian scientists found that 13,000 years to 19,000 years ago, there was no "real" summer on the Earth. At that time, the average temperature in summer was low and sharply volatile.
Kerstin Huber, a scientist of the Institute for Limnology, Austrian Academy of Sciences, pointed out in his latest academic report that, according to the analysis of the remnants of algae and pollen in the sediment of the Lange Lake, Carinthia, Austria, there was no summer in this area at that time, and the range of fluctuation reached nearly 8 degrees Celsius.
Tourists enjoy the warm weather on a beach in the Black Sea coast city of Varna, about 450 km (280 miles) northeast of the Bulgarian capital Sofia, June 25, 2008.(Xinhua/Reuters Photo) The report said, after the end of Ice age about 20,000 years ago, the temperatures on the Earth became warming. About 17,000 years ago, the Earth experienced a drastic cold spell which lasted nearly 2,500 years. Till 14,500 years ago, the temperatures increased again.
At that time, in the area of Lange Lake, "the average water temperature in summer had rapid change. In the warm time, it reached 18 degrees Celsius, while in the cold period, it was only 10 degrees Celsius. The atmospheric temperature in the region also showed a similar fluctuation."
As climate changes, it would directly affect the types of growing plants, such as shrubs, grasses and algae can survive in low-temperature condition, while trees and other plants are only suited to warmer weather.
It just like the tree rings, the sediment mixed with pollen of algae and terrestrial plants has been piling up day by day in the bottom of the lake, which also saves the information of the climate.
Therefore, by analyzing the sediments of algae and pollen of different ages in bottom of lake, it will be able to understand the climatic conditions at that time by identifying the type of the plants.
Austrian scientists collected the sediment cores from the depth of 3.4 to 4.4 meter in the bottom of Lange Lake, which corresponds to an age of 19,000 to 13,000 years ago. By analyzing the types of algae and pollen in sediment cores, they concluded that the temperature of the planet at that time was low and volatile.
With this report Huber reached the first place in the competition of "scientists write press release 2009," which organized by the "dialogue-genetic engineering" association in cooperation with the Austrian Press Agency (APA).
Source:Xinhua
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