Millions of lakes reveal new patterns when viewed as one

Cristian Gudasz, researcher at the Department of Ecology, Environment and Geoscience.

ImageMattias Pettersson

Scientists have long seen lakes as miniature worlds – natural laboratories for studying ecosystems. But understanding what they do at a planetary or regional scale is a scientific challenge. Viewing lakes as an integrated whole can capture emergent behaviors that no lake-by-lake analysis can reveal.

It’s like zooming out and suddenly seeing hidden structures and responses take shape.

Research published in the scientific journal Nature Water now shows that the ensemble of lakes, taken as a composite system, may hold vital clues about how freshwater systems function globally and interact with the planet’s response to climate change.

Working with high-performance computing

Researchers at Umeå University, together with colleagues internationally, analysed large amounts of data from lakes around the world, integrating information on their depth, shape and climate. Using high-performance computing, they built global models that aggregate lakes’ physical characteristics and functions into so-called Über-lakes – composite representations of lakes globally and in different regions or climate zones.

This illustrates how information about the area and depth of individual lakes is combined to create a composite lake or "Über-lake".

“We’ve known for over a century that lakes are powerful ecological testbeds. What we’re showing now is that, taken together as a composite, they also reveal emergent patterns that help us understand how freshwater systems contribute to Earth system resilience,” says Cristian Gudasz, researcher at the Department of Ecology, Environment and Geoscience at Umeå University and first author of the study.

At the heart of this new approach is lake hypsography, how a lake’s area changes with its depth. This determines how it mixes, stores heat, exchanges gases, and cycles nutrients. Hypsography makes it possible to model lake functions and has allowed researchers to uncover new patterns in the composite, such as how lakes in cold, glaciated regions differ structurally and functionally from those in warmer climates.

Lakes mirror land more than oceans

The models also reveal a striking insight: the combined structure of the world’s lakes more closely mirrors land than oceans. Unlike oceans, which are dominated by depth, most lake area worldwide is shallow – a feature that strongly influences their ecological and climatic roles.

“This work bridges the gap between the complexity of individual lakes and the patterns that emerge when you analyse millions of them. It’s like zooming out and suddenly seeing hidden structures and responses take shape,” says Cristian Gudasz.

The concept of Über-lakes makes it possible to not only understand how the world’s lakes reflect environmental change, but also how they can influence it.

“We can average their properties, but what really matters is that composite lakes reveal how lakes interact with the climate system in a way that is more than the sum of individual lakes. Understanding how they function together as a global system gives us a powerful new lens on climate feedback and ecological stability,” says Cristian Gudasz.