NEW YORK -- Lake Baikal is warming faster than the atmosphere, challenging the idea that large bodies of water can withstand global warming, U.S. and Russian scientists said.

Baikal, which holds 20 percent of the world's fresh water, has warmed by 1.21 degrees Celsius since 1946, said Marianne Moore, assistant professor of biological sciences at Wellesley College in Massachusetts. Global temperatures have risen 0.76 degrees Celsius since industrialization, a United Nations panel on climate change said in March.

The Siberian lake holds more than 2,500 plant and animal species, including the world's only exclusively freshwater seal, and some could become extinct by continued warming, said Moore, co-author of a report on Lake Baikal to be published this month in the journal Global Change Biology. The study challenges the idea that thermal inertia of oceans, seas and large lakes would make them more resistant to climate change, Moore said.

"The warming that we're seeing in this lake is of more concern than that of any other lake because of the extraordinary biodiversity," Moore said. "You could potentially lose the Baikal seal."

Beginning in the 1940s, data on Lake Baikal was collected by Mikhail Kozhov, a professor at Irkutsk State University. The research was carried on by his daughter and granddaughter, Lyubov Izmesteva, a co-author of the journal article.

The family has taken samples of the lake every seven to 10 days since 1946, amassing a history that Moore analyzed. The data revealed that the lake's average summer temperature has increased by 2.4 degrees, Moore said.

"My jaw just dropped to the floor when I heard this," Moore said. "I was extremely surprised that the data set even existed."