Michon Scott

Ice older than 4 years once dominated the winter ice pack in the Arctic. Today, only a tiny fraction of old, thick survives.

But fires and other disturbances create patches of "browning" in satellites' view of Arctic vegetation.

Greenland has lost ice mass every year since 1998. Losses in 2021 would have added about 0.2 millimeters to global sea level.

A record-warm autumn boosted Arctic 2020-21 surface temperatures to the rank of seventh-warmest year on record since 1900.

But lower emissions will reduce the intensity of the driest years of megadrought events.