Science, Medicine, Technology

 
 

Water wars

Searing heat and little rain. Once-verdant lawns parched. Precious water in short supply.

Welcome to perpetual drought in the American Southwest, an area with one of the fastest growing populations in the United States. Columbia researchers attribute the region’s new, increasingly arid climate to global warming.

If these scientists are correct, a drought as severe as the 1930s Dust Bowl could ignite conflicts over water and have epic effects on development, immigration, and even international politics.

“The drought is already on the way,” says Richard Seager ’90GSAS, a geophysicist and senior research scientist at the Lamont-Doherty Earth Observatory in Palisades, New York. “Even if we intervene and reduce CO2 emissions now, it will persist. The result of the overall warming of the planet and its intensifying cycle will continue for decades. It takes that long to respond.”

Seager and his colleagues looked at 19 different models of the atmosphere, ocean, and land surface that simulate climate variability and change. Similar to those used for weather forecasting, these models have been developed by groups all over the world and contributed to the Intergovernmental Panel on Climate Change’s (IPCC) report earlier this year.

The models showed a marked increase in barren landscape beginning now and worsening throughout the 21st century. In addition to the American Southwest, large parts of Mexico, the Mediterranean, the Middle East, South America, South Africa, and Australia will dry out. The study, a collaboration with the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, was published April 5 in the online journal Science.

This new climate isn’t linked to a change in sea surface temperature following a particular wind pattern or tidal motion, like the naturally occurring El Niño and La Niña temperature fluctuations in the Pacific Ocean that brought droughts to North America in the 1930s, 1950s, and between 1998 and 2002. Rather, subtropical drying seems to be the result of overall warming of the oceans and atmosphere caused by greenhouse gases, according to the study.

Currently, hot air from the equatorial tropics rises 8 to 12 miles before hitting the stratosphere, and then spreads out north and south, absorbing moisture that would otherwise become rainfall. When it reaches 30 degrees latitude to the north and 30 degrees to the south, it cools and descends again. And as the planet warms, the area where the hot air remains aloft is widening, causing arid regions to expand and become drier.

The study predicts that annual rainfall in the region along the already arid U.S.-Mexico border will drop by 10 to 20 percent by the end of the century, significantly reducing the flow of the Colorado River, which supplies much of the region’s water. A drought that has affected much of the Southwest since 1999, significantly drying the river, may partly be the result of global warming, the researchers say.

Last year nearly one million newcomers moved to Arizona, Nevada, Texas, Utah, and Colorado, according to 2006 U.S. Census figures. Without good planning, water resources could be “stretched to the point of social conflict,” says Seager.
“Being in the desert is unnatural,” he adds. “The whole Southwest is dependent on massive works of engineering. How is that whole system going to stand up to this kind of stress?”

Border and immigration conflicts could flare, too, as drought in Mexico pushes thousands of poor migrants into the U.S. to look for work. International relations with that country also will be strained over the fight for water.

Historian and social critic Michael Davis cited the Lamont-Doherty study in his essay, “Denial in the Desert,” which appeared in the April issue of The Nation, warning that drought has historically set the perfect storm for social conflict.

“Although President Bush now grudgingly accepts the IPCC warning that the Arctic is rapidly melting,” Davis wrote, “he has probably not yet registered the possibility that his ranch might someday become a sand dune.”
— Susan James ’06JRN


 
 

A fall of moondust

As early as the 16th century, astronomers reported seeing tiny puffs of light on the moon’s surface. These reddish, blue, or white flashes have a fittingly nebulous name — transient lunar phenomena, or “TLPs” — given that scientists still can’t decide whether they’re real or the result of optical illusions and wild imaginations.

But Columbia astronomy professor Arlin Crotts insists that TLPs are no UFOs. Recently, he systematically reviewed 450 TLP sightings and found that they were invariably seen in spots where the moon’s surface emits gas. The odds of the overlap is less than 1000 to 1, leading Crotts to theorize in a forthcoming paper that the mysterious flashes are caused by light reflecting off of dust that is kicked up when the radioactive gas such as radon bursts out of the moon’s surface.

To arrive at his theory, Crotts studied TLP sightings documented by astronomers over several centuries, as well as by Apollo astronauts. He mapped their locations against gas eruptions on the lunar surface recorded by NASA’s Apollo 15 mission in 1971 and the robotic Lunar Prospector in 1998. The locations of the TLPs correlate also with areas of the moon where scientists believe a violent lava stew bubbled billions of years ago, before the moon cooled and was pelted with meteors, coating its surface with dusty debris.

Crotts says the discovery could lead to the development of new imaging techniques that would help scientists understand the volatile gases percolating just below the moon’s sleepy surface. But scientists had better hurry, he says, because when the United States sends a fleet of robotic spacecraft to the moon in a few years, the exhaust they generate could complicate future lunar observations.

“If we hope to study the moon in its pristine state,” Crotts writes in the paper, “we must find out what we can early, even before we return to the moon.”


 
 

Are you sure it doesn't hurt?

It’s a boon to snake-oil salesmen and a nuisance to drug developers. But the placebo effect, while well documented, still holds mysteries for scientists: Do fake pills merely trick people into believing they feel better? Or does the power of suggestion actually induce physiological changes?

Columbia scientists say they’re teasing out the answer. A research team led by Tor Wager, an assistant professor of psychology, conducted an experiment recently in which a stimulus hot enough to sting was applied to volunteers’ forearms covered partly with a fake pain-relief ointment. Researchers applied heat, in turns, to those parts of their arms treated with the placebo and those left bare. At the same time, the scientists monitored the subjects’ brains using positron-emission tomography and found that when the subjects saw heat applied to the areas covered in the pain salve, their brains released more opioids, which are the body’s natural painkillers.

“Placebo effects are often observed in clinical practice,” says Wager, “but there have been relatively few scientific studies that document how they work in the brain and body.”

Wager and colleagues from the University of Michigan published their results in the June 26 issue of the Proceedings of the National Academy of Sciences. The paper also pinpoints specific areas of the brain where the most opioids were released. The periaqueductal gray, a section of the brain stem targeted in neurosurgical interventions to control chronic pain, was especially awash in these endorphins. So, too, were the orbitofrontal cortex and anterior cingulate, parts of the cerebral cortex that orchestrate the body’s responses to perceived threat, producing the so-called flight-or-fight response.

Wager says that a precise explanation of the placebo effect’s mechanics might one day help doctors determine the conditions under which it’s best to administer medicine and lead to the development of drug therapies better “informed by knowledge of mind-body interactions.”