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YUP, IT’S DEFINITELY GETTING WARMER


The nightmare is always thus: The princesses glide down Washington D.C.’s Constitution Avenue on their rainbow-colored floats, so fetching in their off-the-shoulder gowns and white gloves. Ahead and behind are marching bands and dancing horses. They arrive at the U.S. capital city’s great walled Tidal Basin, hard by the Jefferson Memorial, and the Japanese ambassador is already there, along with sundry other national and international dignitaries, a sprinkling of celebs, and the media. It is April 9. All is in readiness for another edition of America's annual National Cherry Blossom Festival.


Eye in the Sky


Eye in the Sky Satellite Image

All except for the cherry blossoms.

Once again, the flowers have come and gone. The culprit: too much warm weather, too soon. After the balmiest U.S. winter on record, people will complain that the second-earliest Washington cherry blossom peak is yet another sign of global warming.

So far this phenomenon has been blamed for the melting of glaciers and polar ice caps, rising sea levels, more frequent and more severe floods and droughts, and increases in tropical diseases like malaria, to name a few problems. Why not a few thousand premature buds?

NOW THE OCEANS

More definitive evidence of a global warm-up—and more alarming—has now come from scientists at the National Oceanographic Data Center in Silver Spring, Maryland. Their analysis, published in March by the journal Science, shows for a fact what many have long feared: Temperatures in the world’s oceans are rising.

“In each ocean basin, substantial temperature changes are occurring at much deeper depths than we previously thought,” says National Oceanic and Atmospheric Administration (NOAA) Administrator D. James Baker, who called the finding yet another piece of the world climate puzzle. “Since the 1970s, temperatures at the Earth's surface have warmed, Arctic sea ice has decreased in thickness, and now we know that the average temperature of the world’s oceans has increased during this same time period.”

Some find the implications of this business about the oceans very disturbing, if not frightening. Scientists have long theorized that dry-land warming observed over the past 40 years would be much worse were it not for the oceans soaking up some of the heat. But they haven’t known that for a fact. Now they do; and they also have a good idea of how fast it is occurring.

The fear is that as much as half the world’s increase in temperature since the mid-1950s is still locked in the briny deep—which inevitably will begin releasing it back into the air, possibly over the next few decades.

TOO MUCH OF A GOOD THING?

Although some important aspects of global warming remain controversial, one simple fact has been acknowledged by virtually all sides in the debate: The Earth absolutely is warming up.

A blue-ribbon panel composed of U.S. scientists holding a wide range of opinions on the subject announced in January that the Earth’s surface temperature has risen between 0.7 and 1.4 degrees Fahrenheit (0.39 and 0.78 degrees Celsius) in the past 100 years.

What has not been settled yet is why this is happening, whether and for how long it will continue, and what, if anything, can be done.

A certain amount of global warming is good: It sustains life. The planet isn’t a deep-freeze at night because of something called the “greenhouse effect,” in which some of the sun’s heat is trapped in the atmosphere. Visible sunlight passes easily through a layer of “greenhouse gases” composed of water vapor, carbon dioxide, methane, nitrous oxide and ozone. This layer acts as a thermal blanket that prevents some of the infrared radiation reflected off the surface from caroming back into space.

DISAPPEARING NATIONS

Most scientists hold that the current warming trend can be traced back to the Industrial Revolution. At that time humans began producing ever-increasing amounts of greenhouse gases by burning fossil fuels such as coal, oil and natural gas. These—so the mainstream theory goes—have thickened the thermal blanket, trapping ever larger amounts of heat. Contrarians argue that the current global heat-up may be part of a natural cycle, having little or nothing to do with human activities. Another argument is that increased warming could actually bring important benefits, such as extending planting seasons and making vegetation grow faster.

Almost no one disputes the fact that a substantial rise in sea level would be a bad thing, inundating first a number of oceanic nations such as the Marshall Islands and Vanuatu in the Pacific, and then moving on to eat up places like Manhattan and the world's other great coastal cities.

The plight of Washington’s cherry blossoms pale by comparison. The National Park Service is making no promises, but barring a catastrophic petal-scattering storm, it appears there will be enough blossoms around on April 9 to avoid total embarrassment at this year’s parade.

Then all they’ll have to worry about is next year.

Eye in the Sky is a weekly series that brings you the story behind the headlines using satellite imagery, remote sensing, aerial photography, and maps. This feature is developed by National Geographic News with the sponsorship of the National Imagery and Mapping Agency (NIMA) and Earth-Info. Check out maps and imagery at http://www.earth-info.org.



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More Information
• World temperatures this winter were the sixth warmest on record.
• The United States has just experienced its warmest winter since the government began keeping statistics 105 years ago.
• The previous U.S. records were set last year and the year before, part of a pattern of warm winters that began in 1980.
• Though government meteorologists point to La Niña as a possible culprit for this year’s balmy U.S. winter, they say they can’t rule out global warming.


More Information
  • While scientists continue to argue over the causes and effects of global warming, and whether anything can be done about them, residents of the world’s island nations feel they are running out of time.
  • In the Marshall Islands, World-War-II era U.S. military graves are now covered with water. The airport is routinely flooded during storms.
  • Around the globe, the sea is eating coastlines and claiming bridges, roads, buildings and whole plantations on dozens of islands—some of which stand as little as 3 feet (1 meter) above sea level.
  • Last fall the Alliance of Small Nations pled with large nations to rein in their industrial emissions in order to help them survive.
  • The United States—which leads the world in emissions—still has not ratified the global air-quality agreement drafted in 1997 in Kyoto, Japan. With industrial interests calling the treaty unfair because it gives developing nations such as India more time to comply, Senate ratification is rated as unlikely anytime soon.