Michael Oppenheimer: ‘Storms are becoming more violent’

CHRISTIANE AMANPOUR: Do you think Idai and what’s happening, as I mentioned, in those river basins in the United States right now have the same characteristics, and you’re saying both are a product of this warming, waters in the air and the increasing violence and frequency?

MICHAEL OPPENHEIMER, PRINCETON PROFESSOR OF GEOSCIENCE AND INTERNATIONAL AFFAIRS: There are two things about the big floods in the great plains, they are also characteristic of a changing climate. One of them, is again, there’s a lot of extra boisterous in the atmosphere due to evaporation from the ocean surface and this moisture just feeds in precipitation. In this situation, we’re already going to have heavy precipitation which we had in the great plains over the few weeks preceding the flood. And then, in addition, we had an early melt of the snow pack. The combination of an early melt and heavy precipitation is what’s causing the flood. And an early and intense melting is exactly what you’d expect in a changing climate. So, what we’re seeing here is a vision of what we expect in the future, more violent storms, worst floods, and it’s just sort of one set of extremes that we expect to increase in the changing climate and that have already changed. For instance, as wouldn’t be a surprise in a warmer climate you get more episodes of extreme heat. Extreme heat is extremely dangerous to human health. Also, in a warmer climate, you expect the sea level to rise. Sea level has been rising, it’s due to the warmed ocean, it’s due to melting ice feeding more water into the ocean. That means that when you get a coastal storm in the United States, like for instance, Hurricane Sandy, the flood level gets into places it wouldn’t have before. And perhaps the king of all these events that have these characteristics was Hurricane Harvey in Houston which was so intense in terms of rainfall that it just — you know, 50 inches of rainfall in one episode, unheard of in the United States.