The New York Times reports today that 2006 will finish as either the fifth- or sixth-warmest year on record. It brought the worst wildfire season in U.S. history and blanketed places across the globe in record-setting heat.

The Times’ Andy Revkin gives a good overview of the reasons behind the records in the story. He writes:

All of the reports noted that temperatures greatly above normal were recorded in places as varied as Australia and Scandinavia’s Arctic islands, shattering a variety of longstanding records.

The global climate has warmed and cooled naturally throughout Earth’s history, including a protracted warm spell a millennium ago and a “little ice age” from the 1400s through the 1700s.

But the last 50 years of warming, many climate scientists say, is pressing beyond natural peaks of the last 11,000 years. They say the changes cannot be explained without including a substantial, and growing, push from billions of tons of annual emissions of carbon dioxide and other gases known to trap heat in the air.

In February, the Intergovernmental Panel on Climate Change will release the main findings of its first update since 2001 on causes of global warming. The previous report concluded that most of the warming since 1950 was probably caused by human activities.

Research and fresh computer simulations considered under the new review have greatly strengthened that link, while also closing in on a possible warming of 5 degrees above the 1990 average, more or less, should the concentration of carbon dioxide double from the longstanding peak measured before the industrial era.

For at least 600,000 years before the Industrial Revolution, the concentration of carbon dioxide rarely nudged beyond 280 parts per million. It is now 382 parts per million and rising steadily.

Without a worldwide shift to nonpolluting energy technologies, such a doubling is considered almost unavoidable given the growth in such emissions in both wealthy and developing countries, but particularly in China and India.

ROB DAVIS

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