Global Temperatures Highest in 4,000 Years

08 Mar

Les Rowntree ponders climate change in the company of an Iceland glacier

A new study using ice cores to create climates of the past demonstrates that not only is the current period one of the warmest since the end of the Ice Age about 18,000 years ago, but perhaps even more important the recent rate of warming caused by industrial pollution is much faster than natural warming. So fast is this warming, some scientists opine, that plants and animals may not be able to adapt.

The  news story in today’s New York Times is here. Another worthwhile discussion is found here on Andrew Revkin’s Dot Earth blog. (Revkin, I might add, is a former NY Times environmental reporter who is now freelancing)

Here are some important extracts from the NY Times article:

“Global temperatures are warmer than at any time in at least 4,000 years, scientists reported Thursday, and over the coming decades are likely to surpass levels not seen on the planet since before the last ice age.

Previous research had extended back roughly 1,500 years, and suggested that the rapid temperature spike of the past century, believed to be a consequence of human activity, exceeded any warming episode during those years. The new work confirms that result while suggesting the modern warming is unique over a longer period.

Though the paper is the most complete reconstruction of global temperature, it is roughly consistent with previous work on a regional scale. It suggests that changes in the amount and distribution of incoming sunlight, caused by wobbles in the earth’s orbit, contributed to a sharp temperature rise in the early Holocene.

The climate then stabilized at relatively warm temperatures about 10,000 years ago, hitting a plateau that lasted for roughly 5,000 years, the paper shows. After that, shifts of incoming sunshine prompted a long, slow cooling trend.

The cooling was interrupted, at least in the Northern Hemisphere, by a fairly brief spike during the Middle Ages, known as the Medieval Warm Period. (It was then that the Vikings settled Greenland, dying out there when the climate cooled again.)

Dr. Mann pointed out that the early Holocene temperature increase was almost certainly slow, giving plants and creatures time to adjust. But he said the modern spike would probably threaten the survival of many species, in addition to putting severe stresses on human civilization.


A retreating glacier in Iceland. Note the people on the right side of the photo (photo by Les Rowntree)

“We and other living things can adapt to slower changes,” Dr. Mann said. “It’s the unprecedented speed with which we’re changing the climate that is so worrisome.”

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Posted by on March 8, 2013 in Europe, Global Environment


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