Scientists who probed two kilometers (1.2 miles) through a Greenland glacier to recover the oldest plant DNA on record said Thursday the planet was far warmer hundreds of thousands of years ago than is generally believed. DNA of trees, plants and insects including butterflies and spiders from beneath the southern
That contrasts sharply with the prevailing view that a lush forest of this kind could only have existed in
The samples suggest the temperature probably reached 10 degrees C (50 degrees Fahrenheit) in the summer and -17 C (1 F) in the winter.
They also indicated that during the last period between ice ages, 116,000-130,000 years ago, when temperatures were on average 5 C (9 F) higher than now, the glaciers on
"These findings allow us to make a more accurate environmental reconstruction of the time period from which these samples were taken," said Martin Sharp, a glaciologist at the University of Alberta,
In a separate paper, also published in Science, European experts said they had analysed the world's deepest ice core, enabling them to reconstruct patterns of warming and glaciation over the past 800,000 years. The 3,260-metre (10,595-feet) core was drilled into the
Using traces of the hydrogen isotope deuterium in air bubbles trapped in the ice layers, the scientists built a record of greenhouse-gas concentrations over the aeons, which in turn provides a record of temperature.
They found the temperature varied widely, by as much as 15 C (27 F) over the 800,000 years. In the last Ice Age, which ended around 11,000 years ago, the temperature was 10 C (18 F) lower than today.
The EPICA team had previously analysed the Dome C core to a depth equivalent to 650,000 years ago.
