The Establishment and Demise of the Medieval Nordic Settlements on Greenland: The Role of Natural Climate Change

Comments on a site related to the study of global warming assert that Viking records suggest current global warming is not caused by greenhouse gases. The authors of the published commentary cite historians' claims that the Vikings were able to colonize southern Greenland because of mild weather at the peak of a medieval warm period as evidence that current global warming is caused by the same factor as medieval global warming. Since that occurred at a time before modern sources of greenhouse gases (such as CO2), the essay asserts that these gases are excluded as causes of modern warming.

Many scientists believe that emissions by industrial nations of gases such as carbon dioxide (CO2) into the atmosphere, plus methane that results from large-scale animal agriculture, are responsible for current warming climatic trends. This essay disputes that theory, and asserts that there must be another, natural, cause.