Lake Baikal is the largest freshwater lake in the world, with an average depth of over 5000 feet down and is 25 million years old so is therefore not only the deepest lake but oldest. Lake Baikal contains roughly 20% of the world’s surface fresh water that is unfrozen and is located in the south of the Russian region of Siberia near the city of Irkutsk). has provided scientists with insight into the ways that climate change affects water temperature, which in turn affects life in the lake. The study is published in the journal PLoS ONE today. The research team discovered many climate variability signals, called teleconnections, in the data. For example, changes in Lake Baikal water temperature correlate with monthly variability in El Niño indices, reflecting sea surface temperatures over the Pacific Ocean tens of thousands of kilometers away. At the same time, Lake Baikal’s temperatures are influenced by strong interactions with Pacific Ocean pressure fields described by the Pacific Decadal Oscillation.