Michael Oppenheimer:

Yes, well, sea level is rising, and it's rising at an accelerating pace.

And the reason for that is — you said it — the Greenland and Antarctic ice sheets are losing ice faster and faster. They're dumping into the ocean. And that's a major cause of sea level rise.

And that's also behind — that, largely, is the human-caused warming of the Earth. The second thing to be concerned about is that sea level rise is projected to cause a large change in the frequency of occurrence of extreme water levels at the coasts.

And these are the things that cause big floods. For instance, when a storm like Hurricane Sandy comes along, and there's a storm surge, if it's rise riding on top of a higher sea level, it just pushes the water to a higher level in the places inland, where people live.

And the third thing that we have to know about this problem is that we basically face at the extremes two types of futures. The changes can keep accelerating, because, under the business-as-usual scenario, that's what happens. Sea level just keeps rising and rising at a faster pace through 2300.

That's the furthest we went out, the year 2300. An alternative is to start the kind of strong emissions reductions that were agreed to in the Paris agreement in 2015. And, in that case, sea — the rate of acceleration of sea level slows. Sea level eventually, long, centuries out, stabilizes. And that means that we buy time.

That would give us a chance to adapt to the problem. If we don't slow it down, it's going to become unmanageable.