The Viking colonization of Greenland in the 10th century and their mysterious abandonment of that colony 400 years later may have had nothing to do with climate change as has been believed, a new study argues.

Many scientists have suggested a "Medieval Warm Period" from the 10th to the 12th centuries allowed Viking ships to travel from Iceland across ice-free seas to Greenland to create settlements there - settlements that were then abandoned by the mid-1400s when the climate got colder in the "Little Ice Age" lasting from around 1300 up to 1850, the theory says.

However, a new study suggests the so-called Medieval Warm Period wasn't all that warm in southern Greenland, researchers report in the journal Science Advances.

A geological analysis of rocks deposited by retreating glaciers all but rules out variation in local Greenland climate as a reason for Norse settlements there being abandoned, they report.

"We have found no reason to believe that it was any more warmer at the start of the colonization than at the end," says Columbia University glacial geologist Nicolas Young. "It looks like the climate was by and large pretty stable."

It is likely other factors played a part in leaving Greenland, he suggests.

The Norse settlements in Greenland date to around 985 when ships led by Erik the Red voyaged from Iceland to southwestern Greenland.

At the height of the Viking settlements there, between 3,000 and 5,000 people lived in Greenland, but between 1360 and 1460 the settlements disappeared, leaving only ruins - and a mystery.

Many scientists have long suggested climate variation between the time they arrived and when they left as a factor.

However, the geological analysis shows that during the time of the beginning of the Viking presence in Greenland the extent of glaciers there was about the same as during the subsequent Little Ice Age.

While there definitely was a Medieval Warm Period, there is increasing evidence showing it was for the most part limited to continental Europe, Young explains.

"It's becoming clearer that the Medieval Warm Period was patchy, not global," he says. "The concept is Eurocentric [because] that's where the best known observations were made. Elsewhere, the climate might not have been the same."

The study suggests that the warm period never reached Greenland, study researchers from Columbia and the University of Buffalo say.

"Our study suggests that when the Greenland Norse arrived, it was at least as cold as when they left some 400 years later," Young argues. "If the Vikings travelled to Greenland when it was cool, it's a stretch to say deteriorating climate drove them out."

Photo: Basheer Tome | Flickr