Sierra Summit

Conversations and observations about California's mountains

September 4, 2008
New Climate Study: Warmest in 1300 years
A new study published online by the Proceedings of the National Academy of Sciences provides more data indicating that temperatures across the northern hemisphere are now at a record high.

The authors compiled historic surface temperatures from tree rings, marine sediment, ice cores and other sources and concluded that temperatures over the past 10 years are higher than at any time in the past 1,300 years. It's even warmer today, the authors say, than during the Medieval warm period when the Vikings colonized Greenland. 

You can read the paper at:

For an summary of the paper by the PNAS, go to:

Thanks to - an environmental news service - for posting a story about the  study at:

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About Sierra Summit

The Author
Tom Knudson lives in the Sierra Nevada and travels widely throughout the range. His hobbies include fly-fishing, backpacking and cross-country skiing. He is the recipient of numerous journalistic awards, including two Pulitzer Prizes, one for a 1992 Sacramento Bee series "Sierra in Peril," a watershed work about environmental threats to the mountain range. E-mail Tom at

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