Da: Patrizia Lalicata <laliteach@gmail.com> Data: 14 novembre 2013 00.32.50 GMT+01.00 A: akoma@tin.it
Inviato da iPadhttp://www.pbs.org/newshour/bb/climate-change/july-dec13/storms2_11-12.html
Transcript GWEN IFILL: For more on what we learned about this typhoon and concerns heard in Warsaw and elsewhere, we turn to two who watch this closely. Kevin Trenberth is a climate scientist at the government's National Center for Atmospheric Research. And Jeff Masters is director of meteorology at Weather Underground, a commercial online weather service. Welcome to you both.
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I want to start with you, Kevin Trenberth. Maybe you can help people understand the basics. Cyclone, hurricane, typhoon, what's the difference, if any? KEVIN TRENBERTH, National Center for Atmospheric Research: Just the region that they
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occur in. They're really the same phenomenon. The typhoon is in the Pacific Northwest. The cyclone is sort of Australia and India, the Bay of Bengal, for instance. And hurricanes are in the Eastern Pacific and the Atlantic. GWEN IFILL: And, Jeff Masters, just talk about this one, Haiyan. How worse is this than what we usually see and what causes it to be this intense. JEFF MASTERS, Weather Underground: We don't often see storms get this strong. I mean, the top winds of 190 to 195 miles per hour, there have only been four or five storms over the ocean that have ever reached that intensity. And when it hit land at 190 to 195 miles per hour, we never seen that before. And the way these storms get so strong is they extract heat energy out of the ocean. They convert that heat to the energy of their winds. And the waters to the east of the Philippines have the largest area of deep warm waters of anyplace on the planet. GWEN IFILL: So, Jeff Trenberth, so -- I'm sorry -- Kevin Trenberth, so this is unique, this kind of force, this kind of impact to this area of the world? KEVIN TRENBERTH: That's certainly the warmest area in the global ocean. And, also, it's been warming up at the greatest rate in the global ocean in recent times. GWEN IFILL: So why -- if this is true then -- and the Philippines have sustained several of these every year -- or a few every year at least -- why didn't they see this coming? Why was this such a surprise? KEVIN TRENBERTH: Well, there have certainly been other big storms this year. There was one in Japan in midOctober and also in the Bay of Bengal that went into India. Those were also Category 5 storms. And this one is one of several that have occurred this year. This one just happened to make landfall at full -- at, you know, full intensity. GWEN IFILL: So, Jeff Masters, how do we track them? How do we see them coming? JEFF MASTERS: We track them via satellites in the Pacific Ocean. Unfortunately, we don't have hurricane hunter aircraft anymore in the Pacific, so we have to rely on kind of lower-quality sorts of satellite estimates. But these estimates are pretty universal in showing that this storm was one of the strongest of all time. GWEN IFILL: Well, I want to ask you both this -- and this is a question everybody's asking today, which is, what is
driving this? Is climate change, as we saw the Filipino representative to the World Climate Conference talk about in Warsaw, is this being driven by climate change, by warming of the planet, starting with you Jeff Masters? JEFF MASTERS: We don't have good enough observations. And they don't go back in time far enough to tell for typhoons and hurricanes. These storms have a lot of natural ups and downs and we really haven't been observing them very well to be able to tell for sure if they have been changing or not. But the predictions for the future are pretty solid. As you warm up the oceans, you will tend to make the strongest storms stronger. GWEN IFILL: How about that, Kevin Trenberth? Are the oceans just warming up inexorably and making this happen? KEVIN TRENBERTH: Well, firstly, the global ocean, we have had measurements of altimeters from space making measurements of the global ocean since 1990 -- late 1992. And since then, the global ocean sea level has gone up by 2.5 inches. In the vicinity of the Philippines, it's gone up by about eight inches, just to the east of there. Part of that is because of changes in the winds in that area, which has piled the water up in that region. But it also means that the warm water is exceptionally deep. So the sea temperatures are higher by over a degree Fahrenheit or so on a global basis because of global warming, because of human influences. And going along with that, the air in the atmosphere is warmer and moister. And that's what fuels all of these storms. The environment that all of these storms are occurring in is simply different than it used to be because of human activities. GWEN IFILL: Jeff Masters, is it human activities in that region, or is it human activities globally that you see which are driving the sea levels up in that area? JEFF MASTERS: It's human activities globally. Unfortunately, the people who are least to blame for emitting carbon dioxide into the atmosphere are the ones that are suffering the worst. It's the people in Africa, in the Philippines. The poorer countries are really feeling the impacts of these sorts of extreme events we have seen lately. GWEN IFILL: Let me ask you both for hopefully a hopeful way of butting this up, starting with you, Kevin Trenberth, what to do about it. What kind of precautions should countries in the path of a storm like this be taking? KEVIN TRENBERTH: Well, be prepared. Recognize, firstly, that this is on the cards. The projections are that we will have bigger, more intense storms, although there may be fewer storms overall. But then it's very haphazard as to just which area experiences these at any -- in any particular year or in any particular location. But then you need to be prepared. In the U.S., one of the things that happens is improving building codes, and this has been a problem in the developing countries in particular like the Philippines. There are certain things that you can do in that regard, but the Philippines is certainly in an area where they always have experienced typhoons. And, you know, the infrastructure has not been there. GWEN IFILL: Jeff Masters? JEFF MASTERS: Kevin covered half the story. We need to adapt to these changes, do smart things about building on coasts. But the other part of the coin is, we need to pull less -- put less carbon dioxide into the atmosphere. We need to stop putting these heat-trapping gases in that are increasing the temperature of the planet and contributing to these sort of violent changes to our weather we have seen in recent years. GWEN IFILL: Jeff Masters of Weather Underground and Kevin Trenberth of the National Center for Atmospheric Research, thank you both so much.