CSIRO should establish if there was medieval warming Down-Under

THE deferral of Australia's emissions trading scheme for three years allows us time for additional scientific studies that may be critical in shaping future legislation.

A touchstone in the debate on causes of global warming is the record of global temperatures of past millennia. Most who follow this debate are familiar with the cooling from the 16th to 18th centuries known as the Little Ice Age; this is generally accepted as a global phenomenon. Most are also aware of the Medieval Warm Period covering much of the 9th to 15th centuries. This has been the source of greater debate because, while it is clear in anecdotal descriptions from Europe, such as Vikings growing crops in Greenland, it is less clear whether it is a global phenomenon. The debate has high stakes because the rate of warming and temperatures attained in Europe during the MWP are of similar order to the warming of past decades. If the MWP were to be proven to be global, then the basis of present science stating that industrial-era carbon emissions are the dominant cause of today's warming would be significantly undermined.

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