Complete freezes have been rarer in the past century. On Feb. 5, 1918, during one of the coldest New York winters on record, the Hudson froze solid as far south as Harlem. In 1947, an icebreaker recently returned from capturing a German weather station in the Arctic cut a channel up the Hudson to Albany, allowing emergency fuel and food to reach the capital.

Research shows that climate change is reducing the extent and duration of river ice. In a 2020 study of the world’s major waterways, scientists helped track ice formation on rivers wider than 90 meters to forecast how a warming climate might soon reshape them.

Ice boats used to be a thing on the Hudson. It’s too warm for what is essentially a cross between a sailboat and an ice skate to really work today as a means of getting around.