You can’t open a McDonald’s ketchup packet without the little notch. Try it, okay?” noted climatologist Richard Alley.
Without the little notches, plastic ketchup packets are almost impossible to open no matter how much you pull or tear. Cracks in the world’s ice sheets are like those little notches, Alley said. Once these cracks appear in ice sheets, the stress concentrates there and eventually can lead to large sections of ice falling off and melting quickly.
Alley, professor of geosciences at Pennsylvania State University, used the analogy to describe how ice sheets can rapidly break apart due to preexisting “cracks” or “notches” in the ice produced when meltwater opens small crevices and then makes them big ones, he said. “When you make these cracks bigger, it makes [the ice sheet] break way faster,” Alley said at this year’s Comer Abrupt Climate Change Conference.
It’s going to get ugly real quick.