One Lake Holds About a Fifth of the World's Fresh Surface Water
Lake Baikal is the oldest and deepest lake on Earth, and it holds more water than all five North American Great Lakes combined.
Key points
- One lake in Siberia holds about a fifth of all the fresh surface water on Earth.
- Lake Baikal contains more water than all five of North America's Great Lakes combined.
- UNESCO, which listed Baikal as a World Heritage Site in 1996, describes it as the oldest and deepest lake in the world, containing about 20 percent of the world's total unfrozen freshwater reserve.
One lake in Siberia holds about a fifth of all the fresh surface water on Earth. Lake Baikal contains more water than all five of North America's Great Lakes combined. It is also the oldest lake on the planet and the deepest. Each of those records belongs to the same crescent of blue water, and the reason behind all three is a crack in the Earth that never stopped opening.
The numbers
UNESCO, which listed Baikal as a World Heritage Site in 1996, describes it as the oldest and deepest lake in the world, containing about 20 percent of the world's total unfrozen freshwater reserve.
The depth runs past 1,600 metres, more than a mile of water at the deepest point. The age is around 25 million years. For scale, most lakes on Earth are younger than 20,000 years. They fill with sediment or drain away on timescales that Baikal has outlasted a thousand times over.
The volume is the number that bends the picture. Baikal holds roughly 23,000 cubic kilometres of water. The five Great Lakes, Superior, Michigan, Huron, Erie and Ontario, hold less put together.
A lake that is still being born
Baikal sits in a rift valley, where the Earth's crust is slowly pulling apart. That is why the lake exists at all. A normal lake is a dent that fills in. A rift keeps deepening, so sediment cannot win the race to fill the basin.
The rift still widens today, by small amounts each year. Baikal is not a leftover from a finished process. It is a slow ocean in the making, caught at the lake stage: some geologists note that rifts like this one are how new ocean basins begin.
Life found nowhere else
Isolation plus time equals invention. Hundreds of species in and around Baikal live nowhere else on Earth. The most famous is the nerpa, the Baikal seal, one of the only truly freshwater seals in the world, hundreds of kilometres from the sea it somehow came from.
Tiny crustaceans keep the water famously clear by filtering it. In winter the lake freezes into ice so transparent that visitors photograph boats and people appearing to float above the dark water far below.
Why one lake matters to everyone
A fifth of the fresh surface water on Earth sitting in one basin is not just a trivia record. It is a single point of weight in the planet's water system. What flows into Baikal, and what climate change does to its ice, its currents and its unique food web, touches a reserve that no other lake can replace.
Most people will never see it. But the next time a map shows that thin crescent in Siberia, the scale has changed. It is not a big lake. It is a fifth of the world's fresh water, wearing the shape of a lake.