Russian and American scientists have found that the world’s largest lake, located in Siberia, is becoming warmer, another sign of climate change.  

They have expressed surprise because it was thought this lake with its vast volume of water and a unique water circulation would be more resistant to climate change.

Lake Baikal contains 20 percent of the world’s freshwater and is the world’s oldest lake and its deepest. It was declared a World Heritage site because of its biological diversity—2,500 plant and animal species, including the freshwater seal found nowhere else.

Overall, the average temperature of the lake is 4 degrees Celsius, and it begins freezing in early fall. But, decades of data collection show significant warming of the surface waters and long-term changes in the food web. According to a recent report on the lake’s health, “Increases in water temperature (1.21 degree Celsius since 1946), chlorophyll (300 percent since 1979), and an influential group of zooplankton grazers (335 percent since 1946) have important implications for nutrient cycling and food web dynamics.”

Interestingly, the rich documentation of the lake can be traced to one Siberian family. In the 1940s, Mikhail Kozhov began analyzing water samples. His daughter and his granddaughter continued the program year-round even though temperatures drop to -50 degrees Fahrenheit during the winter. Mikhail’s granddaughter is a co-author of the study that will be published in a future issue of Global Change Biology.