For the first time, scientists think they’re watching a fast-moving river of ice being born. These so-called ice streams are rapid, long-lasting flows of ice that form in the middle of more static ice formations known as ice sheets. There are only a handful of them on Earth. They form in remote parts of the arctic and antarctic and, once established, can last decades or even centuries. Until now, no one had ever seen one emerge.

But now, in a new paper published Nov. 21 in the journal Geophysical Research Letters, a team of glaciologists argues that another, shorter-term event that began in 2013 in the Russian…