Sea ice plays many important roles for the global climate: Its white surface can reflect energy back into space, helping the planet cool. It also acts like a blanket for the ocean, insulating it and preventing ocean heat from reaching the atmosphere. Less sea ice means more heat goes in Earth’s systems, warming the atmosphere and the oceans.

Just 5.53 million square miles of ice had formed as of March 22, the smallest maximum extent since satellite records began in the 1970s.

Scientists have reported that ice in the Arctic Sea saw its weakest winter buildup since records began 47 years ago, highlighting climate change’s global impact. The Arctic’s sea ice reaches its peak each March before a six-month melt season.