Credit: NASA

This video shows how the sea ice minimum has changed from 1979 to 2020 in the Arctic. Each year the amount of sea ice varies with the seasons. The amount decreases during the summer so that the minimum amount of sea ice occurs in the early fall, before temperatures start dropping and the amount of sea ice grows again. But as Earth has warmed, the minimum amount of sea ice has decreased to be about half of what it was forty years before.