DAVID GREENE, HOST:
I mean, this has just felt like a busier, more dramatic hurricane season. So what exactly does that mean? Well, let's ask Marshall Shepherd. He's a professor of geography and atmospheric sciences at the University of Georgia. He also worked for NASA and was president of the American Meteorological Society. Thanks for being here this morning.
MARSHALL SHEPHERD: Hey. Thank you for having me.
GREENE: So Sally was over the Gulf of Mexico for days. It made landfall, suddenly changed directions. I mean, is that at all typical of a storm this size, or are we seeing something different here?
SHEPHERD: Well, you know, I wrote in Forbes over the weekend - last weekend that this was going to happen, that we were going to have a slow-moving storm that would likely, irrespective of its category, be a rainfall disaster. And that's what we've seen. There was a slight jog a bit to the east, but it was certainly within the hurricane error that we get with our models right now. So I actually think the forecast was pretty good. And anytime you're in the cone, you're at risk. I think we have to educate the public that hurricanes aren't points or lines; they're areal. And that's why we issue a cone.
GREENE: Well, I mean, this storm season in the Atlantic has seen 20 named storms so far. That's the earliest we've seen this many storms at this point on record. How significant is that to you?
SHEPHERD: Yeah. You know, we saw that we were going to have an active Atlantic hurricane center. If you look at some of the early season forecasts, if you will, it was clear that we were going to have conditions conducive to hurricanes - warm sea surface temperatures, no El Nino. In fact, we are shifting to a La Nina right now, what - which actually helps that even more. But of course, there's also amazingly warm sea surface temperatures and ocean heat content. And as I often say, that's the fuel supply. That's the gasoline for hurricanes. And right now, they're running on 93 octane, not 87.
GREENE: So there are some experts who have said these bigger, slower, wetter storms and more storms is due to climate change. I mean, you mentioned warmer temperatures. I mean, is - do you see the link as that simple, or how do you see this?
SHEPHERD: It's a bit complex. Look. I served on the National Academy of Sciences panel in 2016 that looked at this problem of attribution - can we link weather to climate change? And we can. There's certainly some things that are more attributable to others. Hurricanes sort of fell in the middle because we know there's certainly some impacts - the climate change on hurricanes.
I think what we're seeing - there's peer-reviewed literature that suggests that storms in the North American continent are slowing down in response to the atmospheric patterns that are due to climate change. And of course, we know sea surface temperatures are warm. And most of the global warming is in the oceans anyhow, and that warming is coming back to the atmosphere through things like hurricanes.
But what concerns me the most - and I think people along coasts have to get used to this - these rapidly intensifying storms. That's probably related to warmer ocean heat content due to climate change, but it is a bit more nuanced answer. We don't blame every single storm on climate change. But these storms are certainly indicative of what our future holds and even our immediate current situation, as well.
GREENE: Yeah, like this season even.
What is your message to people who live in some of these coastal communities that are at high-risk areas? I mean, I think a lot of people who have lived there for a long time feel like they know the drill. A hurricane's coming; they know what to do. But do they need to rethink their plans now?
SHEPHERD: They do need to rethink. My message is, get this - these words out of your vocabulary. I lived through so-and-so storm in the past. Yes, you may have, but the current and future generation of hurricanes is different, perhaps, than what you've lived through. So we have to kind of change that mindset. We also have to remove this notion of, oh, it's just a Category 1 or Category 2. We hear that often. In fact, what we know is rain can be a significant factor irrespective of category.
GREENE: All right. Talking about this busy hurricane season with Marshall Shepherd. He's a professor of geography and atmospheric sciences at the University of Georgia. We might have to come back to you again as this season goes on (laughter). Thank you so much for your time this morning.
SHEPHERD: Happy to be here. Transcript provided by NPR, Copyright NPR.