Climate change could also have natural causes, says scientist

A SCIENTIST has claimed climate change could be caused by natural conditions as well as humans after finding ancient DNA in Greenland that indicates the region was much warmer during the Ice Age than previously thought.

Martin Sharp, a glaciologist at the University of Alberta, took part in research project which collected the oldest ever-recorded DNA samples.

He had previously supported the idea that global warming was caused by humans, but the project raised some doubts, according to an article published yesterday in the Science journal.

The DNA was discovered at the bottom of a 2km-thick ice sheet and came from trees, plants and insects of a boreal forest estimated to be between 450,000 and 900,000 years old.

Ice underneath the glacier had frozen and preserved the DNA samples.

They suggest the temperature of the southern Greenland boreal forests at the time was probably between 10C in summer and -17C in winter.

The reduced glacier cover means the global ocean was probably also between one and two metres higher during that time compared to current levels, the journal said.

Mr Sharp said: “These findings allow us to make a more accurate environmental reconstruction of the time period from which these samples were taken, and what we’ve learned is that this part of the world was significantly warmer than most people thought.”

He now believes there is evidence that climate warming on the current scale is possible through natural conditions.

He said: “It could mean that our current warming is the result of both natural processes and human influences, and we may be heading for even bigger temperature increases than we previously thought.”

A separate study suggests the ice sheet in southern Greenland may be much more stable against rising temperatures than was thought.

Researchers analysed ice cores from locations in Greenland and extracted DNA that revealed a surprising variety of plant and insect life.