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Features May 2004: Volume 1, Number 2
   

It’s the End of the World as We Know It
by Heather Henter

 
     

Is the R.E.M. song too apocalyptic? Scientists at Scripps Institution of Oceanography bring us face to face with the bleak realities of global warming and the consequences of our present-day energy consumption.

Global warming is here. That is immediately clear when you talk to climate scientists at Scripps. Denying global warming is the scientific equivalent of denying that the earth is round, according to Richard Somerville, meteorologist at Scripps. The average global temperature has risen 0.6° C. in the last century. During that time, Northern Hemisphere temperatures rose more than at any time in the last 1,000 years. The 1990s were the warmest decade on record, and the year 1998 was the hottest.

Switzerland is wrapping the upper Gurschen glacier with reflecting foil to try and forestall its melting. Houses in the Arctic sink and sag because the permafrost is melting. Arctic sea ice is breaking up earlier in the season, harming polar bears by shortening their hunting season. Virtually all the world’s glaciers are melting and those in Glacier National Park will likely be gone in 30 years. Antarctica is shrinking. Sea levels are rising and low-lying countries are feeling the threat. The tiny country of Tuvalu in the southwest Pacific Ocean already has a plan to evacuate to New Zealand. Any one of these problems alone could be a scientific anomaly but these changes, and more, are not isolated events. They are part of a consistent pattern all in the same direction—
a warming planet.

“ This is the granddaddy of all environmental problems,” says Charles Kennel, director of Scripps, an institute that has been a leader in the climate-change game for the last half-century. “It is the one environmental issue that affects every human being, every living creature . . . on the surface of the earth.” What will happen if global warming continues, unchecked? Tim Barnett, marine geophysicist at Scripps, predicts serious calamities in our near future, and thinks current debates in Washington will seem inconsequential compared to future disasters due to global warming. “I have to laugh talking about social security in 2042; what a joke. They (politicians) will have a lot more serious problems on their hands between now and then.”

Despite the evidence of current warming, and the urgency felt by scientists like Barnett, some people still see global warming as a controversial topic. Oklahoma Republican James Inhofe stood on the floor of the U.S. Senate in October 2003 and called global warming a hoax, more religious belief than science. And Michael Crichton’s novel State of Fear, portraying global warming as a malevolent conspiracy launched by homicidal environmentalists, has been hailed by some as an authoritative treatise on the science. But among the actual researchers, is the reality of global warming a contentious topic?

 

Naomi Oreskes, History of Science professor at UCSD

No. “I study scientific disputes, this isn’t one of them,” says Naomi Oreskes, History of Science professor at UCSD. To come to this conclusion she analyzed all the scientific papers published on climate change that were listed in a bibliographic database from 1993 to 2003. Her results were striking. Of the 700 or so papers that were relevant to current or future climate change, all explicitly or implicitly agreed with the view that in the last 50 years Earth warmed because of human-produced greenhouse gasses.

“ It is no more a ‘belief’ to say that Earth is heating up than it is to say that continents move, that germs cause disease, that DNA carries hereditary information,” Oreskes wrote in an 2004 op-ed piece in the Washington Post. “This is not a dispute about science,” she added in an interview with @UCSD magazine, “this is a dispute about policy.”

The Greenhouse Effect

Not all greenhouse gasses are bad; the greenhouse effect is a natural phenomenon that makes our planet livable. If it weren’t for gasses like water vapor and carbon dioxide (CO2), our climate would be like the moon—colder and with extreme differences between brutally frigid nights and sizzling, hot days. But unlike the moon, the earth has an atmosphere that traps heat. Cloudy nights are warmer than clear nights because of the heat-trapping effect of water vapor in clouds. But global warming has occurred because humans are intensifying the greenhouse effect. Burning fossil fuels to drive our cars, cool our homes, and run our factories releases tons of CO2 into the atmosphere that will stay there for a century.

Enter Scripps

In the beginning, climate-change science was all about what caused ice ages. Not all of these dramatic changes in climate were millions of years ago. Europe and surrounding areas were warmer around 900-1300 A.D., allowing the Vikings to settle in Greenland, and it was colder from about 1300-1900, as is evidenced by paintings of ice skaters and snowy scenes in English towns, which now only rarely see temperatures below freezing. Our climate has always been highly variable.
The role of gasses such as CO2 in climate change was first understood in the 1800s. The first scientist to predict that industrialization would increase atmospheric CO2, and subsequently temperature, was Svante Arrhenius, grandfather of current Scripps faculty member Gustaf Arrhenius. With only pencil, paper and six months of tedious calculations, which he called the most boring six months of his life, according to his grandson, he calculated that a doubling of CO2 would raise the average global temperature about 5 or 6° C, eerily similar to current predictions. But scientists assumed that the oceans, which already contained much more carbon than the atmosphere, would absorb any excess CO2 produced by industrial activities.

As might be expected, the oceans were how Scripps entered the global warming game. Scripps’ Roger Revelle went to Bikini Atoll to study the effects of nuclear tests on ocean chemistry and unexpectedly discovered that the oceans were not limitless sinks for CO2. Revelle was intrigued enough to hire a young upstart, Dave Keeling. Keeling was the first to show that atmospheric CO2 was, and is, steadily rising (see page 29). That was the beginning, and the science of climate change, at Scripps and around the world, has never been the same.

Ancient Bubbles

Jeff Severinghaus studies bubbles. Not just any bubbles, but bubbles of ancient air locked deep in polar ice. Unlocking these air samples reveals a striking fact: in the past our climate changed very rapidly. According to Severinghaus there have been times when the climate warmed as much as 15° C (the difference between an ice age and a non-ice age) in only 10 years.

Severinghaus regularly travels to Greenland and Antarctica. In such places with permanent snow and ice, the difference between summer and winter creates annual layers that can be read like tree rings, although ice layers are even more precise. Scientists can also identify global events like dust storms and volcanic eruptions that help calibrate the dating.
The longest and oldest core is two miles long and can be dated back 900,000 years, giving us information about the planet’s climate even before modern Homo sapiens existed. Handling a two-mile-long piece of ice, 4 inches in diameter, is a challenge. The solution is that they cut the core into
1-meter lengths as it is being extracted, store them in cardboard tubes (carefully labeled), and ship them to the National Ice Core Laboratory in Denver, “a freezer the size of a Wal-Mart,” according to Severinghaus.

Shipping and storing ice around the globe is no small task and there have been disasters. One American ship carrying an ice core lost power and sat in the tropics for days. What had once been invaluable scientific data turned into some very overpriced water.

Severinghaus uses his samples to analyze the gasses that have been trapped in bubbles in the ice and identifies small changes in the abundance of different isotopes, or forms, of nitrogen and argon, which are stable, common and predictable components of air. “The only thing that affects them is temperature in the snow and a few other processes we can correct for,” he says. “This makes a clean recorder of temperature.” When there is a change in temperature, the heavier and lighter isotopes of these elements move differently through the snow. When the snow turns to ice it is no longer porous and the air is trapped—and Severinghaus has a story to decipher. Luckily for Severinghaus these changes are imposed on a calendar of sorts—the annual layers in the ice. A change in the ratio of isotopes is evidence of climate change, but seeing that change within a small number of layers is evidence of abrupt climate change. Severinghaus has documented these abrupt changes at numerous time periods, from 8,000 to 100,000 years ago.

The reason for these abrupt changes is still a great mystery, although the most popular hypothesis has to do with ocean circulation patterns turning off and then on again, due to the different densities of water at different temperatures and salt concentrations. But the important conclusion is that climate change has, at times, been more like a switch than a dial and because the switch has been abruptly flipped in the past, there is no reason to think it could not flip again. Although these abrupt changes occurred long ago, without the influence of humans, that doesn’t mean that humans can’t also trigger such events. Severinghaus makes the point, “Forest fires have natural causes, like lightning. But that doesn’t mean that careless campers can’t also cause forest fires.” PAGE2

 

RELATED LINKS

R.E.M. song lyrics
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Scripps Institution of Oceanography, UCSD
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The Oceans and Global Change
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SIO's Climate Research Division
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Naomi Oreskes, UCSD Historian of Science
VIEW

The Indian Ocean Experiment
VIEW

SIO's Geosciences Research Division
VIEW

SIO's Center for Atmospheric Sciences
VIEW

State of Fear: Hollywood, the News Media and Global Warming
VIEW WEBCAST

Perspectives on Ocean Science: The Oceans and Global Warming: 50 Years of Climate Change Research at SIO
VIEW WEBCAST

Perspectives on Ocean Science: Rapid Climate Change
VIEW WEBCAST

"Tim Barnett, marine geophysicist at Scripps, thinks current debates in Washington will seem inconsequential compared to future disasters due to global warming."