A 160 square-mile chunk of ice broke off from the Wilkins Ice Shelf in Antarctica on Tuesday. The ice, approximately seven times the size of Manhattan, had started to break up in late February. Scientists noticed the movement in satellite images and were able to capture footage and images of the event.

Unlike sea ice, which floats freely on the ocean, an ice shelf is a portion of glacial ice that extends out from the edge of land over the ocean. If this floating portion breaks off and melts, it does not contribute to sea level rise. However, ice shelves often act as “doorstops,” preventing glacial ice further inland from moving. As these ice shelves break off, inland ice is able to move out to sea – which can raise sea level.

Climate change in Antarctica is a complicated picture. Some places on the continent are cooling and adding ice through accumulated snowfall. Other places, such as the Western Antarctic Ice Sheet (of which the Wilkins Ice Shelf is part) are warming and melting. Scientists hope that continued research into the environmental and climate conditions of Antarctica’s past will shed light into the changes observed today.