Arctic sea ice reaches its maximum thickness and extent in March, at the end of winter. On the map, the white color represents the older, stronger, thicker ice. The bars show the amount of ice in each age group, with white being the oldest ice. This animation shows the age of Arctic sea ice in March for every year from 1984 to 2016. The Arctic sea ice cover has transformed from a strong, thick pack in the 1980s to a thinner, younger ice pack that is more vulnerable to melting out in the summer, contributing to lower minimum ice extents. Thick, old ice comprised 45% of the total ice area at the end of winter in the mid 1980s, but comprised only 22% of the total ice area at the end of winter 2016.