The freezing and thawing of Earth's cryosphere—the mostly frozen parts of the land and ocean—can help regulate the planet’s normal function. They can also disrupt weather and communities. 

Consider permafrost ground, which is soil that is continuously frozen for two or more years. The permafrost in the normally frozen Arctic holds one third of Earth’s soil carbon, trapping and keeping it out of the atmosphere. But when temperatures warm and thaw this permafrost, carbon is released into the atmosphere, altering Earth’s carbon cycle and amplifying global climate change.

Glaciers, ice sheets and shelves, sea ice, and snow also freeze and thaw in ways that are alternately expected or unpredictable, beneficial or hazardous. For instance, the predictable freezing of rivers in Alaska can create quick transportation networks for people to dogsled, drive, or snowmobile on. An unseasonable thaw and ice breakup can produce open-water dangers for travelers.

NASA has several datasets for studying freezing and thawing cycles in the cryosphere. These can provide researchers and planners with information to understand how these processes maintain or disrupt the balance of the natural and human world.