泛读教程4IsWeatherGettingWorse.docx

1、泛读教程4IsWeatherGettingWorse泛读教程4-Is-Weather-Getting-WorseIs Weather Getting Worse? Weather seems getting worse and wilder since Mother Nature is full of surprises these days. Global warming, a heated topic of today, is often taken for granted to be responsible for the harsh weather. However, scientis

2、ts, like Kevin E. Trenberth, are cautious in making their judgment. Please read the following article and find out what role El Nio and La Nia play. As you read this, flip your eyes over to the window. The sky is clear, the wind light, and the sun brilliant. Or maybe not Mother Nature is full of sur

3、prises these days. The calendar says its spring, but there could just as easily be a winter blizzard, a summer swelter, or an autumn cold snap on the other side of that glass pane. Almost in an instant, it seems, the weather shifts from one season to another. And wherever it swings, it seems increas

4、ingly likely to be extreme. Consider what Mother Nature slung our way last year in May, typically the second worst month for tornadoes. In less than 24 hours, more than 70 hellholes of wind rampaged through Oklahoma and Kansas, killing 49 and causing more than $1 billion in damages. In June, it was

5、heat, as the Northeast began roasting through weeks of the worst drought since the 1960s; 256 people died. This year in January, blizzards pounded the U.S. from Kansas to the Atlantic Ocean. In April, 25 inches of snow fell on parts of New England. Why has our weather gone wild? Its the question eve

6、ryones asking, but a very tough one to answer. Although many scientists still arent convinced that it has gone wild, some have begun saying cautiously, hesitantly that extreme weather events are occurring with more frequency than at any time in this century, events consistent with the profile of a w

7、arming world. Global warming is real, says Kevin E. Trenberth, head of the Climate Analysis Section of the Center for Atmospheric Research in Boulder, Colorado. The mean temperatures are going up. The key question is: What will it do locally? I think were going to start feeling its effects in the ch

8、anges on extremes. That doesnt mean you can indict weird weather in your neck of the woods as proof. Mother Nature knows how to hide her tracks. She hurls a torrential downpour today and a drought tomorrow followed by gentle rain the next week. To understand a pattern in natural variability, you can

9、t look into the sky; you have got to study data. And for a host of reasons, that isnt easy. But tallying up the damage is. In the last 20 years, this country has been whacked by $I70 billion worth of weather-related disasters hurricanes, droughts, floods, and tornadoes. Thirty-eight severe weather e

10、vents occurred in a single decade, between 1988 and 1999; seven events occurred in 1998 alone the most for any year on record. Globally, insurance companies are calling it a catastrophe trend. In a report issued last December, Munich Re, the worlds largest reinsurer, or insurer of insurance companie

11、s, noted that the number of natural disasters has increased more than fourfold since the 1950s. Earthquakes, which are not weather-related, caused nearly half the deaths in those catastrophes; storms, floods, and other weather woes killed the other half. In 1999, the number of catastrophes worldwide

12、 hit 755, surpassing the record of 702 set only the year before. In its five-point list of causes for increased damage claims, Munich Re blamed population growth first, climate change fifth. Critics may well seize upon this to diminish claims that the weather is getting worse, but taken together, it

13、s a more frightening picture. Thanks to swelling populations in cities and along coastal areas, more of Earths passengers are living in the wrong place at the wrong time. Still, the statistics meteorologists have collected on extreme weather events arent enough to prove that the weather is getting w

14、orse. By their very definition, extreme events happen infrequently, and no one has been collecting scientifically sound data long enough to know how common they are. For example, a storm that happens once a century might require two millennias worth of storm data to draw conclusions. To top it off,

15、the computer models scientists use to study climate crunch numbers on a scale of centuries at a time. Ideally, youd like data sets that go back several hundred years, says Philip Arkin, deputy director of the International Research Institute for Climate Prediction at the Lamont-Doherty Earth Observa

16、tory in New York. But they just dont exist. The U.S. data go back 50 years. Before World War II, its very difficult to come up with good numbers. We have some data on heavy rain events before 1900, but theres nothing useful. Even if scientists could find good numbers, computer resolution is still to

17、o coarse to be able to forecast how something as simple as warming might affect climate in specific spots on the globe. The smallest amount of space on land, sea, ice, and air that scientists can study is about the size of Virginia. If they crank up the resolution by 50 percent to focus on an area h

18、alf that size, they pay for it in computing time a calculation that took 10 days to perform might now need three months. Keith Dixon, a research meteorologist at the National Oceanic and Atmospheric Administrations Geophysical Fluid Dynamics Laboratory in New Jersey, recalls once he was being asked

19、precisely what global warming would mean for state ski resorts. More snow? (Good.) Or more rain? (Bad.) I can understand why businesspeople or politicians ask. If you want to cut fuel, spend money, and make decisions, you need to know why you should be doing this. Adds his colleague, Tom Knutson: I

20、can certainly sympathize with them. But we cant answer it. Since 1995, the literature has suggested that there could be fewer frosts, more heat waves, more droughts, more intense rainfalls, tropical cyclones, and hurricanes in the 21st century when and if CO2 levels double. But these projections ran

21、k low on the confidence scale because scientists cannot say definitively if and how the events might occur. All of which doesnt do the average citizen much good. He doesnt worry about 30-to-100-year shifts in the climate. What gets him is day-to-day weather: This heats killing me. Crops have failed

22、here five years in a row. There have been three bad tornadoes in as many weeks. We live in a society uniquely privileged to learn about weather events and to fear them. The Center for Media and Public Affairs, a watchdog group based in Washington, D.C., reports that media coverage of weather disaste

23、rs more than doubled from 1997 to 1998 alone. Probably as a result, people are starting to blame harsh weather on global warming. Politicians are too. Jerry Mahlman, director of the GFDL, advises the White House on climate change. He remembers sitting in a conference with Vice President Gore, who as

24、ked: Can we say that storms will be more extreme in the greenhouse-enhanced earth? The scientist didnt flinch as he replied, No. Gores shoulders seemed to crumple. Globally, the 1990s stood as the warmest decade for which we have records. Scientists already predict that by 2100, Earth could warm up

25、another 1.8 to 6.3 degrees Fahrenheit. Most of us think heat when we think global warming. Scientists think ice. Theyre worried about what will happen when all that extra heat hits the ice at Earths poles. A dominant hypothesis says that the water cycle will speed up: Heat will hasten ocean evaporat

26、ion, and because hot air can hold more moisture, it could all be whisked away to rain more upon our heads. Five years ago the Intergovernmental Panel on Climate Change, an international collaboration of 2 000 scientists, theorized as much in a well-publicized 56-page report. That same year, a team o

27、f scientists led by Tom Karl, now director of the National Climatic Data Center (NCDC), studied 80 years of U.S. data and confirmed an increase in extreme precipitation events, altered patterns of rain and drought, and rising temperatures since 1970. But the scientists cautioned that the study analy

28、zed only 80 years of data, confined itself to the United States which occupies a mere 2 percent of the globe and found nothing out of the realm of pure chance. Within months came another, stronger piece of real-world data, nailed down by one of the men caught in that January snowstorm. Sifting throu

29、gh historical data, Trenberth had found that more, longer, and stronger El Nios have occurred during the last 20 years than in the previous 120 years. That was unusual, a chance of 1 in 2 000. El Nio, the periodic warming of the equatorial Pacific that induces storms and other climatic events, histo

30、rically occurs once every three to seven years and lasts for up to two years. But even as Trenberth presented his findings at a conference in Melbourne, Australia, the Pacific was experiencing an odd, double El Nio: The first had lasted from 1991 to 1993, a weaker one from 1994 to 1995. Trenberth fl

31、oated an ideal past the audience in his native New Zealand accent: Could this be due to global warming? The idea, Trenberth modestly recalls, caused something of a stir in the audience. Scientists found themselves wondering: What would happen if one of natures storm machines not completely understoo

32、d but still adhering to rhythms as regular as the seasons were pressed into service by global warming? Archaeological evidence suggests El Nio has been around for thousands, possibly millions of years. A known instigator of storms, floods, droughts, and secondary effects like fires, the El Nio-Southern Oscillation could go a long way toward explaining many weather extremes. Under normal circumstances, sea surface temperatures rise in the tropical Pacific, fueling strong thunderstorms. Like a vast climatic mailba