Bob McNabb is one of the keepers of a number that even he can’t fully comprehend: 267 billion metric tons of water. To explain a quantity of this size, the Ulster University glaciologist must use analogies.
Depending on how you look at it, 267 billion metric tons of water is roughly half the volume of Lake Erie. Or six months of discharge from the Mississippi River. Or all the water in a 10-foot-deep swimming pool that’s the size of Ireland. “It’s really hard to grok,” McNabb tells me.
If we could imagine all that water—a pool as big as Ireland—could we also imagine that much ice melting every year for the past two decades?