Washington, July 2 (ANI): A new research, which has reconstructed the extent of ice in the sea between Greenland and Svalbard from the 13th century to the present indicates that there has never been so little sea ice in 800 years as there is now.
Scientists from the Niels Bohr Institute in Denmark conducted the research.
There are of course neither satellite images nor instrumental records of the climate all the way back to the 13th century, but nature has its own ‘archive’ of the climate in both ice cores and the annual growth rings of trees.
“We have combined information about the climate found in ice cores from an ice cap on Svalbard and from the annual growth rings of trees in Finland and this gave us a curve of the past climate,” explained Aslak Grinsted, geophysicist with the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
In order to determine how much sea ice there has been, the researchers needed to turn to data from the logbooks of ships, which whalers and fisherman kept of their expeditions to the boundary of the sea ice.
The ship logbooks are very precise and go all the way back to the 16th century. They relate at which geographical position the ice was found.
Another source of information about the ice are records from harbours in Iceland, where the severity of the winters have been recorded since the end of the 18th century.
By combining the curve of the climate with the actual historical records of the distribution of the ice, researchers have been able to reconstruct the extent of the sea ice all the way back to the 13th century.
Even though the 13th century was a warm period, the calculations show that there has never been so little sea ice as in the 20th century.
“We see that the sea ice is shrinking to a level which has not been seen in more than 800 years,” concluded Aslak Grinsted. (ANI)