CAMBRIDGE, Mass., Oct. 29 (UPI) -- Two-thirds of the plants writer Henry David Thoreau chronicled at Walden Pond in Massachusetts have disappeared due to global warming, a U.S. study contends.

CAMBRIDGE, Mass., Oct. 28 (UPI) -- U.S. scientists studying Henry David Thoreau's journals have found plant families near Walden Pond have reacted in markedly different ways to global warning.

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