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Wednesday, May 28, 2014

Will El Niño Lead To Extreme Weather This Year?

Pictured are sea surface temperatures in the equatorial Pacific Ocean. El Niño is characterized by unusually warm temperatures, and La Niña by unusually cool temperatures in the equatorial Pacific. (NOAA)

Pictured are sea surface temperatures in the equatorial Pacific Ocean. El Niño is characterized by unusually warm temperatures, and La Niña by unusually cool temperatures in the equatorial Pacific. (NOAA)

Early predictions by climate experts say El Niño is coming. The unusually warm temperatures in the Pacific cause different weather patterns in the United States and elsewhere.

The last El Niño was just a few years ago, and the last “super El Niño” was in 1997. That year, from Florida to California, there were storms, tornadoes and mudslides.

Lisa Goddard, director of the International Research Institute for Climate and Society at Columbia University, speaks to Here & Now’s Jeremy Hobson about what El Niño is and what might be in store for this year.




It's HERE AND NOW. Prepare for El Nino. That's the word from climate scientists who say we're probably in for unusually warm temperatures in the Pacific this year, which cause different weather patterns in the United States and elsewhere.

The last El Nino was just a few years ago. And the last super El Nino was back in 1997. That year from Florida to California there were storms, tornadoes and killer mudslides.


UNIDENTIFIED MAN #1: We saw it coming barreling down at us, just screaming down right towards the back of the house where we were standing.

UNIDENTIFIED WOMAN #1: And I, in fact, went back upstairs to get a glass of water and looked out our front picture window and saw this enormous funnel cloud heading straight our way.

UNIDENTIFIED MAN #2: I'm still missing some friends. I don't know where they're at. And I'm just - I'm kind of hoping they're still around, I can run into them, see if they're all right. I know their (inaudible) was completely demolished.

HOBSON: That sound from 1997 from an NPR report. So what are we in store for this year? Joining us now is Lisa Goddard. She's director of the International Research Institute for Climate and Society at the Earth Institute at Columbia University. She's with us from Kingston, Jamaica where she's attending a climate conference. Lisa, thanks for joining us.

LISA GODDARD: Thanks for having me.

HOBSON: Well, it has been a while for many of us, certainly since there's been a super El Nino. That was back in '97, '98. What is El Nino? Remind us.

GODDARD: So El Nino itself is a warming of the equatorial Pacific, mostly in the sort of central and eastern Pacific off the coast of South America. And these events happen about every three to four years, but the spacing could be two years or seven years. So there's a lot of range in how frequently we get El Nino events.

But the warming is quite marked. And so it changes a very large-scale pattern of sea surface temperatures, which has a marked impact on the atmospheric circulation and regional climate.

HOBSON: And what causes that warming?

GODDARD: So the warming is an ocean and atmosphere phenomenon. And once you start getting a warming in those Eastern Pacific waters, it changes the strength of the trade winds. So it actually weakens the trade winds.

And that allows more of the warm water, which would normally be near Indonesia, to move back towards South America. And that weakens the trade winds further. So you can get this positive feedback into an El Nino event.

HOBSON: Now, we heard there what happened in the last big El Nino event back in '97, '98. There was another one in 2009, 2010. What were the results of that?

GODDARD: Yeah, and actually there's been a few El Nino events since '97, '98. So there was one in 2002, 2003 that was about the same size as 2009, 2010. And there are expected impacts. Certainly the countries near the tropical Pacific are more directly affected.

But it leads to, say, decreased Indian monsoon rainfall, for example. So as far away as the subcontinent of India. But more directly, it leads to potential drought in Australia and Indonesia. It can change the strength and the location of the subtropical jet stream that comes into the U.S. So it often leads to more rainfall in Southern California and actually across the southern tier of the U.S.

At the same time, that influence on the jet stream at the end of the year can influence the temperatures in the northern part of the United States. So we typically get warmer temperatures in the northern tier of states, which is good news for them and their energy costs.

HOBSON: Well, and you said rainfall in Southern California. That is being taken as a very good piece of news if it's true, if it actually happens in California, which is in the middle of this severe drought.

GODDARD: Yes, I think that they're very much hoping that this will lead to an increase in their rainy season.

HOBSON: Although, is there the potential for floods like there was back in 1997, '98?

GODDARD: Certainly, because when you get that increased strength in the jet stream, that means more frequent storms are coming in, potentially stronger storms. And if that's coming on top of really dry surface conditions, that can lead to flash flooding if communities aren't prepared, like having storm gutters cleaned out and things like that. It certainly can lead to flooding conditions.

HOBSON: Now, El Nino is also known to cause fewer hurricanes in the Atlantic and more in the Pacific. I know we've already got one in the Pacific right now.

GODDARD: Yeah, that's true. So it does suppress the hurricanes in the tropical Atlantic. That season is just coming up so we'll have to see how that plays out.

So the Hurricane Center is already forecasting a likelihood for less named storms. But even having one modest hurricane - if that single hurricane makes landfall, is still a disastrous event. In the Pacific, though, warmer temperatures that are now seen off the coast of South America and then spreading up Central America, those warm temperatures can fuel the strength of hurricanes in the Eastern Pacific.

HOBSON: So how sure are climate scientists at this point that we are going to have an El Nino event this year?

GODDARD: The outlooks for El Nino event occurring by the end of the year, which is typically the mature phase of an El Nino event, is about 70 percnet based on the most recent outlook. And those outlooks come out every month. An El Nino event in the next month or so is currently about a 50-50 chance.

HOBSON: And is it likely to be a super El Nino or we just don't know at this point?

GODDARD: We don't know at this point. Even with the '97, '98 El Nino, which was already evolving at this time, it was forecast with greater likelihood earlier in the year. We really didn't have a good sense of how strong it was likely to be until about June. So I think we'll have a lot more information in the next month or two about the potential size of this event.

HOBSON: There is one thing we haven't brought up and that is a related event called La Nina. How does that play into El Nino, and when was the last time we had a La Nina?

GODDARD: We've been sort of in a protracted La Nina period, I would say, since the late '90s. And not that we have had more frequent and stronger La Ninas in the 2000s. And that is sort of the opposite of El Nino. We get the cooler conditions in the equatorial Pacific.

The impacts on the U.S. from La Nina events are very much related with drought. So the sort of conditions that we've been seeing in the Western U.S. And even through Texas and the Great Plains, La Nina appears to be playing a role in that.

HOBSON: Lisa, you're speaking with us from Kingston, Jamaica right now where you're at a climate conference. Is El Nino the big topic there?

GODDARD: El Nino's definitely a big topic. I'm here for a climate outlook forum. This is something that's organized very regularly in a virtual sense by the Caribbean Institute of Meteorology and Hydrology to discuss the upcoming season with the met services and the islands here. And once or twice a year, definitely before the wet season, which is where we are today, they get together to discuss all the factors that are influencing their upcoming climate. And so with El Nino, it does reduce the risk of hurricanes, which is very good. But at the same time, it is a likelihood for drought in the region, which is actually not good. Agriculture and tourism are their biggest industries. And so having a lack of water and a lack of water reserves is certainly worrying for these countries.

HOBSON: Lisa Goddard, director of the International Research Institute for Climate and Society at the Earth Institute at Columbia University joining us from a conference in Kingston, Jamaica. Lisa, thanks so much.

GODDARD: You're very welcome. Thank you.

HOBSON: And that hurricane we mentioned that's now in the Pacific Ocean off the coast of Mexico is called Amanda. It's actually now a tropical storm and is expected to weaken even further to become a tropical depression by the end of the week. On Sunday, though, its winds got up to 155 miles per hour, making it the most powerful May storm in the Pacific since 1951.

In the Atlantic this year, as we talked about, because of El Nino, perhaps, the hurricane season is expected to be below normal with only one or two major hurricanes predicted. You're listening to HERE AND NOW. Transcript provided by NPR, Copyright NPR.

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Robin Young and Jeremy Hobson host Here & Now, a live two-hour production of NPR and WBUR Boston.

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