Thursday, May 17th 2012, 5:49 AM EDT
The Little Ice Age, a cooler period of the Earth's recent history, may have been a global event rather than confined to the northern hemisphere, according to a paper published last week.
Some climate skeptic blogs are excited about this finding, and have taken it as a starting point to argue that the rise in global surface temperature over the last few decades is just a natural recovery from the Little Ice Age, implying that it has nothing to do with, for example, man-made emissions of carbon dioxide. We asked one of the co-authors of the paper whether this is a valid interpretation.
The Little Ice Age ( LIA) was a period of colder than average temperatures and glacier advance between 16th and mid-19th centuries. This new paper adds to evidence suggesting that the LIA was a global event, rather than a regional event - something that is still under debate by scientists.
It documents temperature on the West Antarctic Ice Sheet dipped to around half a degree Celsius cooler than average between the years 1400 and 1800, according to a borehole record. This roughly coincides with a more pronounced cooling observed in records from Greenland, suggesting that the cooling was probably global in scale.