Lakes may be quietly helping to keep the Northern Hemisphere cool, and climate models have been missing the effect. A new study explains why it matters. The research, published in Geophysical Research Letters by Sarah Cooley and colleagues, looked at how lakes change the magnitude and timing of the cooling effect from snow and ice, known as the cryosphere radiative effect. Snow and ice reflect sunlight back to space, cooling the planet. The study finds that lakes add their own twist to this process, especially in the transition from winter to spring, when snow and ice cover changes fast. Climate models account for snow and ice, but usually do not separate the contribution of lakes from surrounding land, leaving a gap in the seasonal energy balance. The findings do not mean lakes can offset global warming. They reveal another component of the climate system that must be considered alongside other forces shaping Earth’s energy balance. For model builders, the message is to treat lakes as their own piece of the puzzle. Better accounting could sharpen projections of Northern Hemisphere warming. It is a reminder that the climate system still holds surprises, even in something as familiar as a lake.