Lakes may cover only a small fraction of Earth’s surface, but new research suggests they play a bigger role in regulating the planet’s climate than previously recognized. By reflecting sunlight back into space when covered in snow and ice, lakes in the Northern Hemisphere have a stronger cooling effect than the surrounding land.

Dr. Sarah Cooley of Duke University and colleagues say their results highlight an overlooked part of Earth’s climate system that could be better represented in climate models, which scientists use to understand how the planet responds to changing environmental conditions.