begin collapsing. and what's really important to note about thwaites that's different than virtually any other glacier in the world is it's not melting like a popsicle on a sidewalk on a hot summer day, because of warmer weather. it's melting because the changes in the water temperature is one or two degrees. the water is getting underneath the glacier itself. and the concern is that by melting it from below, it will destabilize a lot of the glacier or most of the glacier and the whole thing will crumble and fall into the sea, kind of like dumping a whole like bag of ice into the water at once. and that is a catastrophe. >> right, so you've got this ice shelf that is cracking, and that shelf, what's key about that is it's a key protector for the glacier. it's buffer zone, it's shield. the thing that stands between it and the water. and to the extent that that goes away, that reduces the