Picture Climate: What’s Snow Cover Got to Do With It?

Photo of snow-covered bridge

About 98% of Earth’s snow cover is located in the Northern Hemisphere where it can have large impacts on climate variability.

We hear a lot about snow during the winter months, but what makes it an important part of Earth’s climate system? That’s where snow cover comes in. Snow cover—or the area of land that is covered by accumulated snow at any given time—helps regulate Earth’s surface temperature when it is present, and it helps fill rivers and reservoirs once it melts away.

Covering an average of 17–18 million square miles of the world each year, snow cover’s large-scale contribution to the climate system is helping balance Earth’s energy budget. Snow cover reflects about 80 to 90% of the sun’s energy back into the atmosphere allowing it to help regulate the exchange of heat between the Earth’s surface and the atmosphere, thereby cooling the planet.

In addition to helping keep the atmosphere cool, snow cover also helps keep the ground warm. Working like an insulating blanket, snow cover holds heat in the ground beneath it and prevents ground moisture from evaporating into the atmosphere. Under just one foot of snow, soil and organisms can be protected from changes in the air temperature above.

While snow cover affects climate, changes in climate also affect snow cover. Overall, warmer temperatures are shortening the amount of time snow is on the ground in the Northern Hemisphere. Recent temperature increases in the Arctic have also led to decreased snow and ice cover in many areas during parts of the year. And, they’ve also led to earlier melting of snow cover, which is changing when and how much water is available in some rivers and reservoirs as well as lengthening the growing season.

Because changes in snow cover can severely impact Earth’s environment and ecosystems as well as people’s access to water resources, scientists continuously measure how much of the planet is covered by snow. In the long term, this record will help scientists understand how snow cover and Earth’s climate are changing, and in the short-term, it can help water resources managers assess and plan for each spring’s snowmelt.

Visit the National Snow and Ice Data Center’s All About Snow page to learn more about this important part of Earth’s climate system. And, learn more about our changing climate in the National Climate Assessment.

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