# News this Week

Science  25 Aug 2006:
Vol. 313, Issue 5790, pp. 1026
1. AVIAN INFLUENZA

# Pushed by an Outsider, Scientists Call for Global Plan to Share Flu Data

1. Martin Enserink*
1. With reporting by Dennis Normile in Tokyo.

In an unexpected show of cooperation, scientists from more than 30 countries have announced a plan to start sharing their often closely held data on avian influenza. A group of influenza researchers, experts in intellectual property and bioinformatics, and a sprinkling of Nobel laureates are calling for a global consortium whose members would commit to putting any genetic data from bird flu into the public domain as soon as possible. Their letter is slated to be published online by Nature this week.

“I am so happy. I feel that maybe I should quit working and start arranging flowers,” says Ilaria Capua, a virologist at Istituto Zooprofilattico Sperimentale delle Venezie in Legnaro, Italy, who kicked off the debate in March when she called for such global openness (Science, 3 March, p. 1224). But other flu researchers caution that many key details remain to be fleshed out, including how to get the governments of affected countries to comply with the deal.

In a strange twist, a key figure in the initiative is a strategic consultant and former TV executive from Santa Monica, California, named Peter Bogner. A complete outsider to the flu community, Bogner co-authored the statement and traveled the world on his own dime in the past few months collecting signatures. Bogner has “been extremely important as a catalyst,” says Nancy Cox, chief of the influenza division at the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, another key player.

Analyzing the genomes of avian influenza samples allows scientists to understand how the virus is spreading and changing over time. But the sequence of many isolates is not publicly available. Some governments don't want to release raw sequence data because it might disadvantage their own scientists or because the information might be used commercially. Some scientists also withhold sequence data while preparing a paper. At the initiative of the World Health Organization (WHO), however, much of the data are available to about 17 labs in a password-protected compartment of the flu database at Los Alamos National Laboratory in New Mexico. WHO defends that system as a way to allay the concerns of some governments while giving key researchers access. But critics argue that all researchers should be able to study the data.

Participants in the Global Initiative on Sharing Avian Influenza Data, as the new group is called, promise to enter any new sequences into publicly available databases such as GenBank as soon as possible, but no later than 6 months after they are generated. The signatories include the heads of WHO's four Collaborating Centers (CDC and its counterparts in Parkville, Australia, London, and Tokyo), Malik Peiris of the University of Hong Kong, Chen Hualan of the Animal Influenza Laboratory of the Chinese agriculture ministry, and many others. Among the five Nobelists are genome veteran John Sulston of the Wellcome Trust Sanger Institute in Cambridge, U.K., and Harold Varmus, president of the Memorial Sloan-Kettering Cancer Center in New York City.

The letter does not spell out how the consortium would operate or how it would protect the intellectual-property rights of those who contribute data. Cox says an international advisory board will hash out such policies. Bogner plans to enlist experts at Creative Commons, an organization that offers flexible copyright licenses on the Internet, and CAMBIA, an independent research institute in Canberra, Australia, that fosters collaboration in the life sciences.

The roster of more than 50 signatories includes some who remain skeptical. “I am not sure if it will be effective,” says Masato Tashiro, who directs the WHO Collaborating Center in Tokyo and thinks researchers should share virus strains as well as genomic data to accelerate vaccine development. Robert Webster of St. Jude Children's Research Hospital in Memphis, Tennessee—who signed on after “Ilaria Capua pulled my chain a bit”—agrees. Still, “it's a very important first step,” says David Lipman, director of the National Center for Biotechnology Information in Bethesda, Maryland. A WHO spokesperson said last week that the agency is studying the letter.

Bogner's role is a bit of an enigma even to those who have worked closely with him. Born in Germany in 1964, Bogner came to the United States in the early 1980s and worked in the TV industry there and abroad before starting his own strategic consulting firm. He says he knew “almost nothing” about flu until he heard about Capua's campaign a few months ago and decided to help out. Well-connected and a frequent participant at the annual celebrity-studded World Economic Forum in Davos, Switzerland, Bogner says he used his “talent to make people talk to each other” to broker the letter. “He certainly has a lot of energy,” says Lipman.

Capua says Bogner initially suggested that he was working for U.N. Secretary-General Kofi Annan. Bogner says that the U.N. is one of his clients but not on this issue; indeed, he says, he hasn't been paid a cent for his flu efforts. “In fairness, there are some aspects of this whole story I don't quite understand,” says Capua. “But we're getting what we want.”

2. MATHEMATICS

# Perelman Declines Math's Top Prize; Three Others Honored in Madrid

1. Dana Mackenzie*
1. Dana Mackenzie is a writer in Santa Cruz, California.

On Tuesday in Madrid, Spain's King Juan Carlos kicked off the International Congress of Mathematicians by awarding the closest equivalent to a Nobel Prize in math to three young stars (see sidebar). But the name on everybody's lips was that of the mathematician who had refused his Fields Medal: Grigory Perelman. The 40-year-old Russian recluse was to have been honored for his proof of the legendary Poincaré conjecture. Instead, his refusal added another chapter to the controversial and colorful saga of the problem and its proof.

First posed in 1904, the Poincaré conjecture has become larger than life because of its apparent simplicity and because so many strong mathematicians tried unsuccessfully to solve it. In 1979, William Thurston, then of Princeton University, upped the ante with a more sweeping version called the geometrization conjecture. Finally, in 2000, the newly formed Clay Mathematics Institute (CMI) focused public attention on the problem by placing a $1 million bounty on the Poincaré conjecture, as well as six other problems. In 2002, Perelman posted two preprints on the Internet, totaling 70 pages, which claimed to outline a complete solution of the geometrization conjecture. (That implies a proof of the Poincaré conjecture, which Perelman did not even mention.) Perelman used a strategy called “Ricci flow,” which Richard Hamilton of the State University of New York, Stony Brook, had developed starting in the early 1980s. Perelman met Hamilton and became interested in Ricci flow while visiting the United States in the early 1990s. In 1995, he returned to his native Russia and dropped off the radar screen of Western mathematicians. His 2002 preprints were a bombshell. The following spring, he backed up his claim in a series of invited lectures at Stony Brook and the Massachusetts Institute of Technology (MIT) in Cambridge (Science, 18 April 2003, p. 417). And then he disappeared again, leaving others to check his proof and explain it to the world. ## Three manuscripts Three pairs of mathematicians stepped up to the challenge. This April, Huai-Dong Cao of Lehigh University in Bethlehem, Pennsylvania, and Xi-Ping Zhu of Zhongshan University in China published a 300-page refereed article in the Asian Journal of Mathematics. Their paper departs from Perelman's proof in certain key places, “due to the difficulties in understanding Perelman's arguments at these points,” in the authors' words. The paper allowed Cao and Zhu to claim “the first written account of a complete proof of the Poincaré conjecture and the geometrization conjecture of Thurston.” In June, Bruce Kleiner and John Lott of the University of Michigan, Ann Arbor, released a manuscript that had evolved publicly online since Perelman's visit. Its gradually increasing detail helped cement the community's acceptance of Perelman's work. “They were the main people who carried the torch forward over the last 3 years,” says Michael Anderson of Stony Brook University. Finally, last month, John Morgan of Columbia University and Gang Tian of MIT completed a manuscript that will be published as a book. Their work, like Kleiner and Lott's, sticks closely to Perelman's outline. Perelman's exegetes have played a crucial role in making his work accessible to other researchers, says James Carlson, president of CMI. “Like a program written in open-source code, many eyes will be looking at it,” he says. “Instead of having to work out the arguments by themselves, mathematicians will be left with the much easier task of verifying that the worked-out details are correct.” ## The wait begins According to CMI's rules, the$1 million for each Millennium Prize can be presented 2 years after the proof is published in a refereed journal. Even though Perelman's own papers have never been formally published, Carlson confirms that the clock is now ticking toward awarding the first prize. “Close to 2 years from now, we will form a committee to study the issue,” Carlson says.

Shing-Tung Yau of Harvard University thinks that Hamilton deserves a share. “For 20 years, he worked on this problem alone, with some help from me. The part he proved is absolutely nontrivial, and it was devised purposely to solve this problem,” says Yau. At present, however, Yau's seems to be a minority view. “Perelman broke through the barriers,” says Robert Greene of the University of California, Los Angeles. “If Perelman's papers didn't exist, I think we would still be stuck. It's the unsticking that counts.”

According to new figures from the World Health Organization (WHO), at the end of June 2006, 6.8 million infected people in low- and middle-income countries needed anti-HIV drugs, but only 1.65 million were receiving them. “We're still behind the eight ball,” said former U.S. President Bill Clinton, whose foundation helps countries negotiate lower prices for antiretroviral drugs. Scaling up access to drugs won't solve all problems, either. “We can't treat ourselves out of this epidemic,” said epidemiologist Kevin De Cock, the new head of WHO's HIV/AIDS program. In his keynote speech, Bill Gates did a crude mathematical exercise and concluded that, with 38.6 million infected people in the world, it would soon cost a minimum of $13 billion a year just for the drugs required to treat everyone in need. “Treatment without prevention is simply unsustainable,” he said. A key limitation to both treatment and prevention efforts is that 90% of infected people do not know their status. De Cock and many others stressed the need to move beyond voluntary counseling and testing to “provider-initiated testing,” in which health-care workers recommend, without insisting, that people get screened for HIV. Botswana for the past 2 years has increased testing with this “opt-out” policy, and nearby Lesotho recently launched a “know your status” campaign. With trials ongoing in several countries, one of the most promising prevention strategies is pre-exposure prophylaxis (PrEP)—providing anti-HIV drugs to the uninfected. Leigh Peterson of Family Health International in Research Triangle Park, North Carolina, described the combined results of studies in Nigeria, Ghana, and Cameroon that involved 936 women at high risk of becoming infected. The women took either the anti-HIV drug tenofovir or a placebo each day. Although too few infections occurred to determine whether PrEP worked, the researchers mainly aimed to assess safety, and no one appeared harmed by the drug. Nor was there any indication that PrEP encouraged people to take more risks, as some feared: Women in both arms of the study reported using condoms more frequently than at the trial's start and also reduced their number of sexual partners. “They're very intriguing results,” said Kenneth Mayer, who directs the Brown University AIDS Program in Providence, Rhode Island. Uganda has been widely praised for reducing HIV prevalence in the 1990s, in part through campaigns that led people to limit their number of partners. But results from a large, multiyear study suggest that such gains are hard to sustain. In the Masaka district—chosen as a representative rural area—prevalence increased in both men (5.6% to 6.7%) and women (6.7% to 8.9%) between 2000 and 2005. New infection rates also were strikingly high in men between the ages of 40 and 49. Leigh Anne Shafer, an epidemiologist with the U.K.'s Medical Research Council who conducted the study with the Uganda Ministry of Health, said she does not know what accounts for the rising prevalence but thinks that people may have “prevention fatigue,” leading to increased risky sexual behavior. More disturbing news came from a report suggesting that “extensively” drug-resistant (XDR) tuberculosis—in which people fail all TB drugs—may be a much more widespread problem than appreciated. Worldwide, only 347 cases of XDR were identified between 2000 and 2004. But Neel Ghandi of Albert Einstein College of Medicine in New York City reported here that of 544 tuberculosis patients in KwaZulu-Natal, South Africa, 53 were dually infected with HIV and XDR TB; 52 died quickly. “It's ominous,” says Gerald Friedland of Yale University, who headed the study. “XDR TB may be present in other locations, but it has not been looked for because it requires culturing TB, and that's minimally available in Africa. It needs to be looked for more aggressively now.” On a more hopeful note, researchers reported encouraging new data about an anti-HIV drug from Merck that won much attention this winter (Science, 17 February, p. 943) for rescuing people who had developed resistance to every other antiretroviral drug. A 24-week study showed that this so-called integrase inhibitor, when given in combination with other antiretroviral drugs to previously untreated people, quickly reduced the virus to undetectable levels. “This is a tremendous drug,” said Joseph Eron, a clinician at the University of North Carolina, Chapel Hill, who has patients in the study. The usual roar of AIDS activists assailing governments and researchers was muted this year, as attendees from many quarters blasted South Africa's leaders for still flirting with the idea that HIV doesn't cause AIDS. Canadian Prime Minister Stephen Harper also attracted scathing reprimands from activists, researchers, and even a U.N. official for not attending the meeting. “Your action sends a message that you do not regard HIV/AIDS as a critical priority,” charged conference co-chair Mark Wainberg, who heads the McGill University AIDS Centre in Montreal, Canada. “Clearly all of us here tonight disagree with you.” Wainberg received a standing ovation. 7. STEM CELLS # Scientists Derive Line From Single Embryo Cell 1. Gretchen Vogel In an advance touted as a way around the current political logjam, scientists have developed a method for deriving human embryonic stem (hES) cell lines without destroying an embryo. Although not yet very efficient, the technique, reported online in Nature this week, could in theory allow scientists to derive new hES cell lines that might be eligible for federal funding under current rules. In the past few years, scientists have proposed several alternatives to deriving hES cells that would not require destruction of a human embryo (Science, 24 December 2004, p. 2174). One idea is to grow a cell line from a single cell removed from an early embryo, leaving the rest of the embryo intact. Doctors do such biopsies when they perform preimplantation genetic diagnosis (PGD), which allows a couple undergoing in vitro fertilization (IVF) to screen out embryos carrying genetic diseases. Last year, Robert Lanza of Advanced Cell Technology (ACT) in Worcester, Massachusetts, and his colleagues reported that they had found a way to culture a single cell from an early mouse embryo so that it grew into a line of hES cells (Science, 21 October 2005, p. 416). Now they have refined their technique to apply it to human cells. The ACT scientists thawed 16 frozen embryos donated by couples who had undergone IVF treatments and no longer needed the embryos. The team then allowed the embryos to develop to the morula stage, at which the embryo contains 8 to 16 cells, also called blastomeres. They used a pipette to separate the blastomeres and then cultured each one separately to see whether it would grow into an hES cell line. More than half of the 91 blastomeres divided at least once, and 28 formed clumps that grew in culture. The scientists transferred the clumps to cultures in which other hES cells, marked with green fluorescent protein, were already growing. In two cases, the transferred cells grew into cultures that behaved like hES cells. (In others, they failed to grow or grew into cells resembling trophectoderm, the cells that go on to form the placenta.) Lanza says researchers could use the technique to derive hES cells from embryos undergoing PGD. Researchers could allow the removed blastomere to grow overnight, giving it time to divide. One cell could then be used for the genetic diagnosis, and the other could be cultured into an hES cell line. The embryo could be implanted and go on to develop into a full-term pregnancy. James Battey, chair of the Stem Cell Task Force at the National Institutes of Health (NIH) in Bethesda, Maryland, says the paper is an interesting proof of principle but doesn't resolve all ethical and legal questions. Federal law prohibits funding for work that “endangers” human embryos, he notes. Because the PGD biopsy does carry some risk to the embryo, he says, it's not clear whether cells derived using the new technique would be eligible for NIH funds. 8. SPACE SCIENCE # NASA Chief Blasts Science Advisers, Widening Split With Researchers 1. Andrew Lawler NASA Administrator Michael Griffin this week read the riot act to the outside scientists who advise him, accusing them of thinking more of themselves and their research than of the agency's mission. Griffin's harsh comments come on the heels of the resignation of three distinguished scientists from the NASA Advisory Council (NAC), two of whom have questioned Griffin's plan to dramatically scale back a host of science projects (Science, 12 May, p. 824). “The scientific community … expects to have far too large a role in prescribing what work NASA should do,” Griffin wrote council members in a blistering 21 August message. “By ‘effectiveness,’ what the scientific community really means is ‘the extent to which we are able to get NASA to do what we want to do.'” The outside engineers, scientists, and educators on the council traditionally offer advice on the agency's policies, budget, and projects. Placed in limbo for nearly a year after Griffin took over as NASA chief in spring 2005, NAC was reorganized this spring under the leadership of geologist Harrison Schmitt, a former U.S. senator and Apollo astronaut who is very enthusiastic about President George W. Bush's plans to send humans back to the moon and to Mars. Schmitt replaced Charles Kennel, director of the Scripps Institution of Oceanography in San Diego, California, who resigned last week from his post as chair of the council's science committee. Two other NAC members—former NASA space science chief Wesley Huntress and Provost Eugene Levy of Rice University in Houston, Texas—resigned last week in response to a direct request from Griffin that they step down. Schmitt and members of that committee have clashed repeatedly in recent months over the role of science at the space agency. In a pointed 24 July memo to science committee members, Schmitt complained that they lacked “willingness to provide the best advice possible to Mike,” refused to back Griffin's decision to cut research funds for astrobiology or recommend an alternative cut, and resisted considering the science component of future human missions to the moon. “Some members of the committee,” he concluded, “are not willing to offer positive assistance to Mike.” Both Levy, a physicist, and Huntress, an astrochemist now at the Carnegie Institution of Washington, D.C., say they support human space exploration but fear that science is now taking a back seat after years of a careful balance between human and robotic efforts. NASA spokesperson Dean Acosta acknowledged that the scientists and Schmitt “weren't working well together,” and that Griffin telephoned Huntress and Levy last week to ask for their resignations. Griffin's memo points to what he calls “the inherent and long-standing conflict of interest” of giving advice to an agency on which members depend for funding. And he offers them a clear way out. “The most appropriate recourse for NAC members who believe the NASA program should be something other than what it is, is to resign.” Huntress says Griffin told him that his advice exceeded the council's charge. “This is a different NAC. Our advice was simply not required nor desired,” Huntress told Science. The current council, he adds, “has no understanding or patience for the science community process.” Kennel, who had been named chair of NAC's science committee, was unavailable for comment, but Norine Noonan, a former NAC member and dean of math and science at the College of Charleston in South Carolina, called Griffin's action “very distressing” for scientists. “If we can't have a robust debate at the NAC level,” she says, “then where in the heck is it supposed to happen?” 9. CHEMISTRY # New in Nanotech: Self-Folding Delivery Boxes 1. Robert F. Service “Some assembly required.” Those words on a box from the store spell agony for a parent. Chemists face similar headaches while designing new drug-delivery agents or trying to control their actions in the body. But researchers in Maryland may have found a pain reliever. In a paper published online last week in the Journal of the American Chemical Society, researchers at Johns Hopkins University in Baltimore, Maryland, reported creating tiny two-dimensional cutouts that fold themselves up into porous cubes and other 3D containers. The containers can then be used to ferry compounds to a site where chemists want them to react. Metal versions can even be steered there using magnetic fields. Researchers say the new nanocontainers could be useful as novel drug-delivery vehicles and in tiny lab-on-a-chip reactors. “This is very elegant work,” says Mauro Ferrari, a nanomedicine expert at the University of Texas Health Science Center in Houston. “It brings an innovative element to the field of controlled release of drugs. [But] it has a long way to go” before it can help patients, he warns. Team leader David Gracias, a chemical engineer, says the idea for porous nanocontainers grew out of decades of work in patterning computer chips. The first steps involved producing ultraprecise 2D structures on flat silicon slabs and other surfaces. In recent years, the chip industry's primary patterning technique, called photolithography, has also spawned efforts to craft everything from tiny gears to microscopic channels and reservoirs for tiny chemical reactors. But making 3D porous containers remained a challenge. Gracias and his lab members—graduate student Timothy Leong, postdoctoral candidate Zhiyong Gu, and undergraduate Travis Koh—made their nanocubes using standard photolithography techniques to etch a series of six squares, 100 to 200 micrometers on a side, each shot through with anywhere from one to hundreds of tiny holes. These squares were attached to one another in a crucifix pattern, with a strip of metal between each square that acted both as hinges and solder. The tiny crucifixes were placed in a liquid bath and heated until the hinges melted. Surface tension along the faces of the crucifixes caused the square faces to collapse into cubes. As the bath cooled, the hinges hardened again, soldering the faces in place. Gracias's team then filled the cubes with different reagents that would leak out at different rates depending on the size of the pores and used them to carry out a variety of chemical reactions. The researchers also used magnetic fields to redirect cubes made out of nickel and other metals. Ferrari notes that metallic nanoparticles capable of delivering drugs aren't new. And he warns that it could take years to prove that the cubes are safe and effective in clinical settings. The “great upside” of the Johns Hopkins team's work, he says, is that they can build upon advances in lithography to create very precise structures. Someday, Ferrari predicts, transistors, sensors, and other information-processing devices may be implanted directly onto their carriers to control exactly when and where chemicals are released. Now, if only parents could get toys to assemble themselves. 10. ASTRONOMY # Satellite's X-ray Vision Clinches the Case for Dark Matter 1. Tom Siegfried* 1. Tom Siegfried is a writer in Los Angeles, California. A fantastically energetic collision between clusters of galaxies has demolished a challenge to the law of gravity, providing the clearest evidence yet for the existence of intergalactic dark matter. For decades, astronomers have inferred that unseen matter lurks within and between galaxies. Luminous stars alone, they realized, don't exert enough gravitational force to explain how individual galaxies spin and clusters of galaxies clump together. Something invisible must be pulling, too. Some of the extra matter in galactic clusters is just hot gas. But even more mass seems to exist in the form of “nonbaryonic” dark matter, made of something other than ordinary atoms. A few holdouts have insisted that the observations could be explained by modifying the law of gravity at great distances. But a new result from the Chandra X-ray Observatory satellite offers clear-cut evidence that dark matter really does infuse galactic clusters. “It demonstrates beyond a reasonable doubt that dark matter exists,” says Sean Carroll, a cosmologist at the University of Chicago, Illinois, not involved in the study. Speaking this week at a NASA briefing, astronomers reported on new Chandra images of the “bullet cluster” of galaxies, 1E0657-56, created by an energetic collision of smaller clusters. It is the most explosively violent such merger ever observed, said astrophysicist Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. The shock wave from the cluster collision dragged the hot gas between galaxies into its unusual shape but would not have affected dark matter, which interacts only via gravity. Consequently, the explosive collision stripped the ordinary gaseous matter away from the nonbaryonic dark matter. “Because of this collision, for the first time, we're actually able to see dark and ordinary matter separated in space. And this proves in a simple and direct way that dark matter exists,” Markevitch said at the briefing. With no dark matter, the gravity of the cluster would remain concentrated on the gas, which vastly outweighs the galaxies it surrounds. But in fact, the gravitational field of the cluster no longer matches the location of the gas. Astronomers measured the cluster's gravitational influence by tracking its effect on the light from more distant “background” galaxies, a phenomenon known as gravitational lensing. The results show a clear separation between the gas and the gravity. “In the bullet cluster, we've seen for the first time a large spatial separation in the sky between where the majority of the normal matter is found and where most of the gravity is found,” said team leader Douglas Clowe of the University of Arizona, Tucson. “This cannot be explained by altered gravity for normal matter.” A paper describing the results will be published in Astrophysical Journal Letters. While the new result specifically demonstrates the existence only of intergalactic dark matter, it strengthens the case for dark matter within galaxies as well. The same dark matter could explain both why clusters of galaxies do not fly apart and why galaxies themselves rotate as rapidly as they do, Carroll says. There is no need to invoke modifications to Newtonian gravity. Carroll pointed out that it remains possible that the laws of gravity may need to be modified. But those modifications can no longer do away with dark matter. “No matter what you do, you're going to have to believe in dark matter,” he said at the briefing. “It is once and for all the case that dark matter does exist.” 11. HYDROENGINEERING # Going Against the Flow 1. Richard Stone*, 2. Hawk Jia 1. Hawk Jia is a writer in Beijing. The Chinese government has begun a massive engineering project to divert water from three southern rivers to the parched north—with unknown consequences BEIJING—A half-century ago, Mao Zedong offered a seemingly simple exhortation to his young Communist nation: “Lend some water from the Yangtze River to the Yellow River.” But the massive engineering challenges and costs of funneling a surfeit of water from China's moist south to its parched north kept Mao's grand vision in check—until now. In one of the biggest civil engineering projects ever undertaken, the Chinese government has embarked on a controversial 500 billion yuan ($62.5 billion) effort to shift water from three southern river basins to its populous and thirsty northern provinces.

The South-North Water Transfer Scheme involves a series of canals, pumping stations, reservoirs, and dams that would supply water to the north for drinking and for irrigation. Excavation is under way on the eastern and central routes, each more than 1000 kilometers long, and last month, engineers completed a tunnel beneath the Caohe River that will allow water on the central route to begin flowing to Beijing in 2008. Work on a third, more complex, route that would link watersheds in Tibet and western China is not expected to start for at least another decade (see map). If all goes according to plan, by 2050, some 44.8 billion cubic meters of water—roughly the annual runoff of the Yellow River—will be diverted northward each year to meet the needs of almost half a billion people. By comparison, California's vaunted transfer system conveys one-tenth that volume of water from north to south.

But the attempt to transform the landscape of central China is not without its critics. There are worries that pollution in southern rivers—the Yangtze, the Hanjiang, and the Huai—will contaminate northern climes, and that the shift will endanger southern ecosystems, especially Tibet's fragile watersheds. “It's quite dangerous,” warns Ye Qian, a climatologist with the U.S. National Center for Atmospheric Research in Boulder, Colorado, and the International Research Center of Creeping Environmental Problems in Lanzhou, China. The project's economics are hotly debated as well.

Still, many Chinese scientists deem the massive waterworks to be the best fix for a looming crisis. Relentless desertification in the north is eroding biodiversity and concentrating pollutants in smaller bodies of water, curtailing supplies of potable water. China's Ministry of Water Resources predicts that even with stepped-up conservation efforts, the annual shortfall of water for drinking and irrigation in the Yellow and Hai river basins will exceed 21 billion cubic meters by 2010. If the water-transfer project were not implemented, officials say, that deficit would swell to 32 billion cubic meters by 2030. The government estimates that 96 million Chinese, mostly in northern rural areas, now lack sufficient drinking water.

“We're trying to recover a healthy water cycle,” says Xia Jun, a hydrologist at the Institute of Geographical Sciences and Natural Resources of the Chinese Academy of Sciences (CAS) in Beijing. Xia believes that the transfer scheme, coupled with water-conservation measures, would do just that over the next few decades. Ye, however, blasts the project as the latest in a string of risky engineering solutions to problems that China could tackle with more benign measures. “If you have the right water management, you can save the same amount that they intend to transfer,” he argues. “Why are they doing this now? Because they have the money and people need jobs. But they need to think more about the consequences.”

## Rearranging nature

One point of universal agreement is that northern China's water resources are growing perilously scarce. Aquifers in the north—an area covering 428,000 square kilometers with a population of 437 million—are being sucked dry. In the Beijing region, for instance, the groundwater table has steadily receded from an average of 10 meters below the surface in 1975 to 35 meters in 2005. In the Haihe River Basin, in which 95% of available water is exploited, the 305 cubic meters of water resources per capita is less than 5% of the global average, says Xia. The Yellow River is so heavily siphoned that in dry months it often peters out before reaching the East China Sea. In 1997, the river stopped short a record 226 days, its dry bed extending as far as 700 kilometers inland. The simple fact, Xia says, is that “North China has become more arid.”

Aggravating the situation are a burgeoning population, intensive agriculture, and rapid industrialization. Amid the boom, few people are mindful of conservation, an attitude that scientists say needs to change. To prevent the squandering of water diverted north, the central government has ordered northern cities to implement water-conservation measures before the diversion begins, says Liu Changming, a top expert on the south-north project at Beijing Normal University. Xia agrees: “We need to build a water-saving society.”

Southern China, on the other hand, is chin deep in water. More than 90% of the Yangtze River's annual flow of 960 billion cubic meters from its headwaters in the Himalayas and tributaries empties into the sea. That statistic also applies to the Hanjiang River, which flows into the Yangtze near Wuhan and will be tapped for the central route.

Scientists have mulled plans for a south-north transfer ever since Mao's famous 1953 proclamation, and Ye says it fits with the government's overall philosophy. “China is driven by engineers,” says Ye. “Mao said, ‘Man can overcome nature.'” But it wasn't until the early 1990s, as China's economy began to heat up and the desiccation of northern China accelerated, that the first feasibility studies were conducted. The Communist Party leadership gave its blessing in 1995, when then-Premier Li Peng, a hydrological engineer who was also a force behind the Three Gorges dam, predicted that the project would “benefit dozens of Chinese generations.”

Work on the 1150-kilometer eastern route kicked off in 2003. Water will be lifted by pumps 65 meters above the Yangtze, the third largest river in the world, to an ancient Grand Canal, segments of which have operated continuously since the 5th century B.C.E. The canal bed, now being widened and deepened, will dive under the Yellow River via a tunnel before reaching its terminus in Tianjin. A branch will conduct water to major cities in eastern Shandong Province. Engineers intend to turn on the taps next year, with plans eventually to divert 14.8 billion cubic meters along this route from the Yangtze, an amount that represents less than 2% of the river's flow.

The 1277-kilometer central route poses a tougher challenge. Its centerpiece is Danjiangkou dam on the Hanjiang River. Engineers are now raising the height of the dam by 15 meters, increasing its holding capacity by two-thirds. The larger reservoir would both supply water for the central route and diminish the threat of periodic flooding in Wuhan, central China's biggest city, and other parts of Hubei Province. As a result, however, some 224,000 people from villages near the reservoir are being relocated; many have already left.

The western route would link the mountainous headwaters of the Yangtze and Yellow Rivers and transfer the most water of the three lines: 17 billion cubic meters per year. It is expected to offset severe desertification and irrigate 2 million hectares across four provinces. Another benefit, proponents say, is that infusing water near the Yellow River's headwaters will reduce sediment buildup along the riverbed and avert or mitigate seasonal floods. However, complicated engineering and unanswered ecological questions are likely to delay construction until at least 2020, says Liu.

Environmental concerns have dogged the project every step of the way, starting with pollution. Some $1.75 billion is being spent on measures to clean up the Huaihe River, a feeder for the eastern route and one of the most polluted rivers in China. The Hanjiang River is also a major headache. “The middle and lower parts of the Hanjiang have already been seriously polluted by industrial wastes,” says Du Yun, a hydrologist at CAS's Institute of Geodesy and Geophysics in Wuhan. Four major algal blooms on the river since the early 1990s have triggered mass fish kills. The central route would draw off approximately 16% of Hanjiang's flow, concentrating pollutants and prompting Du to anticipate “big impacts on the environment and water ecology.” To mitigate that threat, engineers later this year will start excavating a canal from the Yangtze to the middle Hanjiang to boost flow. Ideally, the canal would connect with the Hanjiang as close as possible to the Danjiangkou dam, but due to engineering difficulties, it will enter 300 kilometers downriver, leaving a significant stretch of the Hanjiang heavily polluted, says Du. One planned remedy is to dam and dredge the Hanjiang to boost flow. But in-depth studies on whether this will dilute pollutants, as hoped, are “still lacking,” he says. To make matters worse, Li Guoying of the government's Yellow River Water Resources Commission announced earlier this month that the water ministry plans to start ferrying water northward from the Danjiangkou reservoir as early as 2008—a full 2 years before the Yangtze-Hanjiang diversion canal and the dredging projects are completed. The gap “could cause irreversible losses to biodiversity in the middle and lower Hanjiang River,” Du asserts. One life form that scientists would rather not see blossom as a result of the project is the schistosome parasite. Oncomelania snails, riddled with the blood flukes that cause schistosomiasis, are endemic in the part of Jiangsu Province where the eastern route originates. Zhou Xiaonong of the Institute of Parasitic Disease in Shanghai has been lobbying authorities to take steps to control schistosomiasis—such as lining riverbanks with cement and setting up more observation stations for the parasite—before the eastern route begins moving water. Another concern stems from reduced flow in the southern rivers. Experts are not worried about the impact during the peak summer and early autumn months, when regular downpours recharge the Yangtze and other rivers. But even the intended 5% reduction during the dry season or a drought could have serious consequences for the Yangtze Basin, says Chen Jiyu, a hydrologist at East China Normal University in Shanghai. Such a reduction, he says, could lead to seawater backwash into the Yangtze estuary that would reduce freshwater supplies to Shanghai and weaken its capacity to dilute pollutants. Zhang Jiyao, director of the water-diversion office of the State Council, has vowed that the spigots feeding the eastern route will be shut during dry seasons. Project engineers have set the cutoff at flows of less than 8000 cubic meters per second at the Datong hydrological station on the lower Yangtze, some 600 kilometers upriver of the estuary. Chen, however, argues that the threshold should be at least 50% higher, considering the heavy demand for water by industry and agriculture along the lower Yangtze. He has urged planners to build a facility to gather runoff and water-quality data in the estuary. However, Chen says, “I have seen no effort to collect these data and integrate them into water-diversion decisions.” At the same time, the canal could revive one long-standing woe. The falling water table, although crippling water supplies, has ameliorated soil salinity in the fertile agricultural plains of Hebei and Henan provinces. A rising water table could carry salts back up to the topsoil, says Liu. One straightforward solution would be a ban on irrigation channels along the water-diversion routes, says Pei Yuansheng, a water-resource expert at the China Institute of Water Resources and Hydropower Research in Beijing. Only wells should be permitted, he says. Pei would like the government to subsidize the sinking of new wells. A bigger question is how the proposed western route will impact the region's ecology. “Our main target for ecological protection is leaving enough water for fish,” says Liu Suxia of the Institute of Geographical Sciences and Natural Resources in Beijing. Her team has been reviewing previous ecological studies and querying local experts. Detailed surveys, she says, will come later. ## Fiscal infighting The economic impact of the scheme, like its ecological consequences, is opaque. The necessity to overcome gravity on the eastern route could make the new water twice as expensive, raising its price in Tianjin to the equivalent of approximately 50 U.S. cents per ton. Much of that increase is expected to be passed on to consumers. And it's not clear which authorities will manage the resource, both in reservoirs and stored in underground aquifers. “Feuds over water ownership penetrate nearly every step of planning, construction, operation, and even the scientific research process,” says Chen Xiqing, a hydrologist at Hohai University in Nanjing. “A key problem,” he says, is that China “lacks a legal framework to coordinate conflicts between the central and local governments and between different regions.” Shandong and Jiangsu provinces are embroiled in a fight over water rights, sources say. Ironically, climate change could render parts of the water scheme superfluous. Chinese and U.S. models predict that northern China will become increasingly wet as average temperatures rise. That shift may begin as early as next decade, Ye says. He and others are pressing the government to reconsider plans to forge ahead with the western route, which is not a fait accompli. But “no one can stop” the eastern and central routes, says Ye. The vast experiment is well under way—and both China and the world are awaiting the consequences. 12. HYDROENGINEERING # Controversial Rivers Project Aims to Turn India's Fierce Monsoon Into a Friend 1. Pallava Bagla NEW DELHI—China's gargantuan South-North Water Transfer Scheme (see main text) may not hold the record as the largest civil water project for long. India is planning a similar endeavor that could cost twice as much and eventually shift four times the volume of water. The$120 billion Interlinking of Rivers Project would primarily divert monsoon runoff from 12 rivers in eastern India to parched western states via canals, tunnels, and reservoirs. The project has support across the political spectrum; India's President A. P. J. Abdul Kalam says it offers “the promise of freeing the country from the endless cycle of floods and droughts.” But critics view it as an impending disaster and decry the envisioned resettlement of tens of thousands of people. “It would spell doom for the people who would be affected and uprooted,” contends Medha Patkar of the Save the Narmada Campaign in Barwani.

For India, water is feast or famine. During the monsoon season from July to September, when the country receives 80% of its annual rainfall, vast swaths of the east are inundated, while the west suffers crippling shortages. Flood damages have climbed from $13 million in 1953 to an annual average of$335 million, according to the government's Task Force on Interlinking of Rivers. Yet India's billion-plus people—16% of the world population—have access to only 4% of the planet's fresh water, posing a rising threat to India's food security. Although irrigation over the past half-century has quadrupled India's grain harvest to 213 million tons per year, production must double by 2050 to keep pace with India's population growth, experts say, and irrigated land must increase from 95 million to 160 million hectares. India's maximum irrigation potential through conventional methods is assessed at 140 million hectares. The Interlinking Project, backers say, would more than close that gap, providing water to irrigate some 35 million hectares.

More than a century ago, planners fantasized about diverting India's eastern floodwaters into southern and western river basins, but the idea was dismissed as far-fetched. “Gigantism always casts an irresistible spell on our bureaucracy,” says an ardent critic of the plan, Ramaswamy R. Iyer, a former secretary of the Ministry of Water Resources who's now with the Center for Policy Research in New Delhi. But India has proved adept at smaller-scale transfers. In the late 19th century, the Periyar River in southern India was dammed and a 1740-meter-long tunnel excavated to carry water eastward to the neighboring Vaigai Basin. The waterworks still functions, irrigating 81,000 hectares and driving a 140-megawatt power station. And in the north, the Rajasthan Canal uses a barrage and canals to divert Himalayan glacial runoff to Rajasthan's deserts. “These projects have been highly beneficial and have not caused any noticeable environmental damage,” says Suresh Prabhu, former Interlinking task force chair.

The idea of the grandest waterworks of all was resurrected not by engineers but by a lawyer, Ranjit Kumar, who in 2002 petitioned India's Supreme Court to force the government to take the long-standing scheme off the shelf and implement it. In a 5 May 2005 ruling, the court decreed that the project must start by 2007 and the bulk of it be completed by 2016. In response to concerns from Bangladesh, which gets most of its fresh water from Himalaya-fed rivers, India has pledged to hold off on part of the project that would tie Himalayan rivers into the scheme.

Audacious in scope, the project would link 37 rivers through 12,500 kilometers of canals. Backers recite a litany of benefits. Each year, some 178 cubic kilometers of water would be diverted westward, providing drinking water for at least 10 million households and irrigation water. Run-of-the-river turbines would generate 34 gigawatts of electricity, while storage dams would mitigate flooding, particularly in the Ganga and Brahmaputra basins. The canals, planned to be 50 to 100 meters wide and more than 6 meters deep, would facilitate navigation. Engineering challenges include burrowing through mountains and moving water against gravitational flow, whereas societal issues include the resettlement of people from river valleys converted into reservoirs.

In this first stage of the mammoth project, which won government approval last August, a 230-kilometer canal will be dug to divert water from the Ken River to the Betwa River in northern Madhya Pradesh province. A dam and small hydroelectric plant will be built in the Panna tiger reserve. Work on the $1.1 billion pilot effort is under way and scheduled to be completed in 8 years. Critics assail even this relatively modest beginning. The Ken-Betwa link “will cause horrific devastation,” says physicist Vandana Shiva, director of the Research Foundation for Science, Technology, and Ecology in New Delhi. According to a foundation analysis, forest clearance to excavate the Ken-Betwa canal will exacerbate runoff and degrade biodiversity. And in Madhya Pradesh, Shiva says, farmers might shift from producing rice and legumes for the domestic market to water-intensive crops such as sugar cane. The result, Shiva predicts, will be “ecological breakdown” and “political instability.” Prabhu scoffs at the claims. The project, he says, “is expected to greatly reduce the regional imbalance in the availability of water” and thereby reduce the potential for strife. A dearth of credible data hampers debate, says Tushar Shah of the International Water Management Institute in Colombo, Sri Lanka: “What should have been a national debate based on analysis, reason, and cold calculus is rapidly turning into a cacophony of discordant prejudices, opinions, preferences, and assertions.” Shah is leading an analysis of the overall project for the Consultative Group on International Agricultural Research in Washington, D.C., assessing factors such as flow rates and exploring strategies for maximizing use of runoff. A report is expected in April 2008. A thorough study “is essential for evaluating the long-term consequences of interlinking rivers,” says V. Rajamani, a geologist at Jawaharlal Nehru University in New Delhi. Flooding, he notes, is a natural process that enriches basins with silt deposits. Key issues, such as the effects of sedimentation loss and alterations in water and nutrient supply, “are huge unknowns,” he says. Those uncertainties could make the Interlinking of Rivers Project a$120 billion gamble.

13. HURRICANE KATRINA

# One Year After, New Orleans Researchers Struggle to Rebuild

1. Jocelyn Kaiser

Labs are up and running but short-staffed, and the departure of key scientific talent means the city's research institutions have much rebuilding ahead

NEW ORLEANS, LOUISIANA—The Medical Education Building at Louisiana State University (LSU) still has a smudged black line from floodwaters, and the bottom doors are blocked by orange pylons and marked “Contractor Entrance Only.” A visitor has to find her way in via the crosswalk from the student dormitory next door. But up on the sixth floor, developmental biologist Oliver Wessely's lab is humming with students doing experiments. Setting aside a petri dish of frog embryos, Wessely reflects on the past year: He's come a long way since Hurricane Katrina, which cost him his frogs and all but one (luckily, pregnant) transgenic mouse. “Right now, I can't complain,” he says. “My research is progressing.”

Life has changed, however: For one, the hallways are eerily quiet. Five of his department's 12 research faculty members have left or been laid off. “You have much less people around here. Much less interactivity. … The biggest issue for research will be [restoring] a more intellectually stimulating atmosphere,” Wessely says.

One year after the 29 August 2005 storm, research in New Orleans is getting back on its feet. Most lab buildings have been open since early 2006, and scientists say they're catching up on experiments. Worries have eased somewhat since the National Institutes of Health (NIH) announced last month that it will allow its grantees to apply for 1-year funded extensions, giving them a chance to make up for the lost year before they must compete for funding again. “I don't want to suggest everything is perfectly back to normal. … We have tremendous challenges. [But] I would say we have beaten the odds,” says Paul Whelton, dean of Tulane's medical school and senior vice president for health sciences of the Tulane Health Sciences Center.

But not everyone is so optimistic. Researchers still lack some basic lab services and are hampered by staff shortages. Medical schools have suffered deep cuts in clinical and teaching faculty, which erodes morale. And although the overall number of research faculty members at the city's institutions hasn't dropped that much, some departments and programs have sustained serious losses in numbers of both key senior scientists and young researchers.

The future of research in New Orleans, scientists say, will hinge on whether new faculty members—as well as postdocs and graduate students—will want to live and work in the struggling city. That's unclear in a place that still has less than half its pre-Katrina population and remains plagued with scarce and overpriced housing, boarded-up businesses, and power outages—not to mention the threat of another hurricane. Full-scale faculty recruiting, officials say, is on hold until the end of November. “We've got to get past this hurricane season,” says Whelton.

On the surface, New Orleans's main universities with research programs—LSU's Health Sciences Center (LSUHSC), Tulane, and the University of New Orleans (UNO)—appear relatively unscathed. At Tulane's uptown campus, which suffered little flooding, stately late 19th-century limestone buildings are again surrounded by manicured lawns.

After replacing walls and repairing flooding damage to basement power equipment, Tulane managed to open its downtown medical campus in January. LSUHSC's downtown complex—except for the badly damaged dental school—officially opened in February, although elevators weren't working in some buildings, and amenities such as distilled water were lacking for several months. Many labs at UNO on Lake Pontchartrain have also been open since late January, although some items, such as fume hoods and power outlets, are not completely fixed.

Following the evacuation, most scientists spent the fall of 2005 at far-flung host universities. Once they began trickling back in January, they set about repairing or replacing equipment and replenishing reagents, cell lines, and animals lost during the power outages—this time, taking care to send some samples and transgenic animals to colleagues outside New Orleans. Companies that sell reagents and mice have offered discounts, the state and universities have come up with some money to rebuild labs, and NIH and the National Science Foundation have awarded supplements for replacing equipment and supplies. “I don't think anybody's not able to do the science they want to because of a lack of funding,” says Joseph Moerschbaecher, vice chancellor for academic affairs at LSUHSC.

The modest progress can't make up for the loss of critical mass, however. Universities now lack support staff—janitors, secretaries, and the like—as well as lab workers. LSU's transgenic animal facility lost its director and remains closed, Wessely says, and other core facilities, such as a peptide synthesis lab, are unavailable. LSUHSC genetics chair Bronya Keats says, “There's no doubt that it's still taking longer to get things done.”

Even more painful, many researchers have lost postdocs and grad students. Tulane biochemist Art Lustig says half his lab staff didn't return. “They were just afraid,” he says. The remaining grad student and postdoc, who are catching up on studies of yeast telomeres, “are exhausted.”

All three universities suffered a slump in new grad students this fall. LSU attracted only half the usual 50 to 60 new basic science students. New enrollment at Tulane's medical school is down by about one-third, says virologist Robert Garry. Whereas these schools managed to retain most returning grad students, UNO has been hit much harder: Its total graduate enrollment, which includes business and liberal arts programs, has dropped to 2000, about half what it was prestorm, says UNO graduate school dean Robert Cashner.

The biggest blow to universities' research efforts, however, is the loss of faculty members. Several hundred were temporarily laid off or lost their jobs due to budget pressures at LSU and Tulane last December (Science, 16 December 2005, p. 1753), in large part because both medical schools had few patients and no major hospitals for months. Many worry that LSUHSC will have to furlough more staff members if it can't open hospitals quickly and begin generating clinical income.

Although most researchers were shielded from these cuts, many have left town anyway, often taking their grants with them. LSUHSC has lost about 20 of 80 NIH-funded faculty members, both young professors and leaders such as cancer center director Oliver Sartor, now at Harvard, and Stephen Lanier, chair of pharmacology, who's leaving for the Medical University of South Carolina. Tulane's cancer center lost five of 34 basic researchers, says director Roy Weiner, including Tyler Curiel, who left this month to head the San Antonio Cancer Institute in Texas. Tulane's School of Science and Engineering is down 15 of 115 faculty members, including ecologists, psychologists, and biomedical engineers. And UNO's College of Sciences has lost 19 research faculty members, says Cashner. “It's almost like an artery was cut open,” says David Mullin, chair of Tulane's cell and molecular biology department, which lost four of 12 faculty members.

Surprisingly, both medical schools say their NIH research funding has held steady, partly because of new grants; half of the $13 million drop in overall research funding at LSU (see graph) was clinical income from halted trials, says Moerschbaecher. ## Slow recovery Many of those who chose to leave either had lost their homes or their spouses were laid off, say officials from all three universities. “Some people just couldn't take it,” says Moerschbaecher. Others were discouraged by the gloomy prospects for New Orleans's recovery. “It's the situation in the city more than the school,” says LSU neuroscientist Jeffrey Magee, who left for Howard Hughes Medical Institute's Janelia Farm in Virginia after 20 years in New Orleans. Indeed, those remaining still face tremendous obstacles. The city is only now getting traffic lights working; it still suffers from power outages and water-main breaks. In faculty enclaves such as Lakeview and Gentilly, many houses are up for sale, and some faculty members are living in rented apartments or Federal Emergency Management Agency trailers while battling insurance companies and deciding whether to rebuild. Many businesses remain closed. “It's going to take 10 years” to recover, predicts LSUHSC biochemistry chair Arthur Haas. With living conditions so grim, universities are scrambling to keep more faculty members from leaving. LSU hopes that a$25 million pot of money proposed by the state board of regents for new, collaborative research and education projects will persuade some to stay. Tulane last spring set aside $10 million in insurance money for small grants to help researchers rebuild their labs; this fall, they can compete for another$10 million for new projects. “This is a tough town right now. … People need a reason to stay,” Whelton says.

One bright spot, say medical school officials, is the 1-year funded extensions that NIH decided to allow after sending a delegation to New Orleans in March. “That's going to be incredibly helpful to us,” Moerschbaecher says. NIH is making the awards available only to researchers who stay in New Orleans: “Anything that helps stabilize the institutions will be beneficial,” says Joe Ellis of the NIH Office of Extramural Research. Although the announcement was only for single-investigator awards, NIH will consider extending multi-investigator projects on a case-by-case basis, Ellis says.

Even with such enticements, many scientists say they are keeping their eyes open for job offers elsewhere. “If I can't get postdocs soon, in 2 years, I'll lose everything. I know what it takes to get grants,” says biochemist Iris Lindberg of LSUHSC.

Despite the obstacles, university officials are optimistic that they will be able to recruit new faculty members. UNO received a couple of hundred applications for two computer science faculty slots, Cashner notes. Nicholas Altiero, dean of Tulane's School of Science and Engineering, says he's had “some very good candidates” for two open positions, one in environmental science, a field that is poised to grow in post-Katrina New Orleans. Even biomedical scientists may see opportunities, suggests cancer researcher Matthew Burow of Tulane. Tulane “is a different institution, but there are positives,” he says. “Younger scientists may see a place where they can … begin to build programs. There will be people out there who hopefully see that.”

14. METEOROLOGY

# Sharpening Up Models for a Better View of the Atmosphere

1. Richard A. Kerr

The exponential rise of computing power and the 2002 arrival of the great Earth Simulator computer have driven atmospheric models to extremes

Machines simulating Earth's atmosphere are producing ever-more-detailed pictures of weather and climate, thanks to ever-increasing computer power. And that new detail is now beginning to let researchers shed some of the approximations and down-right fabrications they once needed to get anything useful out of their models. The new view of the atmosphere “looks very, very different” from that of less detailed model simulations, says modeler Jerry D. Mahlman of the National Center for Atmospheric Research in Boulder, Colorado. “It's a very important thing to do.”

Supercomputers now run at once-undreamed-of speeds—many tens of teraflops (tens of trillions of floating point operations per second). In weather forecasting models, part of this exponentially improving computing power has always gone into increasing model resolution. Modelers do that by moving the isolated points at which atmospheric properties are calculated—the model's grid points—closer together. It's like a pointillist painter going from big splotches of color to smaller and smaller dabs that show greater and greater detail. Global weather-forecasting models are down to grid-point spacing of a few tens of kilometers in the horizontal. Climate modelers, in contrast, have favored a spacing of about 200 kilometers, says modeler Kevin Hamilton of the University of Hawaii, Manoa. That gave them simulations that bore some resemblance to real weather maps but that run for not just a week but centuries.

Then, in 2002, Japanese researchers turned on the 40-teraflops Earth Simulator. “The Japanese had two advantages,” says Hamilton. “They were willing to invest an enormous amount of money, on the order of a billion [U.S.] dollars.” And they had some very clever engineers figuring out how to build a unique, hybrid supercomputer that efficiently combines the conventional approach of simultaneously running large numbers of cheap processors with processors specially designed to accelerate atmospheric model calculations.

Spurred by the Earth Simulator, climate and meteorology researchers in Japan and around the world are pushing the resolution of their global models to new extremes. In a Geophysical Research Letters paper published 14 July, modeler Bo-Wen Shen of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and colleagues report how they simulated 5 days in the life of Hurricane Katrina on NASA's newer, 61-teraflops Columbia supercomputer at the Ames Research Center in Mountain View, California. Global models have generally failed to produce intense tropical storms, but when the resolution was dropped from 20 kilometers to 10 kilometers, the simulated Katrina intensified to about the same extremely low central pressure as the real Katrina. It had winds nearly as strong spiraling around a suitably compact eye.

Shen and his colleagues then turned off the model's convective parameterization, the part of the model that tells it how, where, and when buoyant air will rise in puffy clouds and thunderheads. Even without that guidance, the simulated storm bore the same strong resemblance to the real thing. Apparently, the higher-resolution model was producing realistic convection—which powers tropical cyclones—all by itself from the smaller details of hurricane workings, without being told what to do.

In another high-resolution tropical cyclone study, reported last April, modeler Kazuyoshi Oouchi of the Earth Simulator Center in Yokohama, Japan, and colleagues simulated 10 years of global tropical cyclone activity both under present conditions and under warmer, greenhouse conditions. On the Earth Simulator, they ran a 20-kilometer-resolution model. Under present conditions, the model produced a reasonable rendition of the number, strength, and geographic distribution of storms. Under greenhouse warmth, the number of tropical cyclones around the world actually decreased 30%, but the number of more intense storms increased substantially. That supports upward trends in storm intensity recently reported from analyses of observations (Science, 5 May, p. 676).

Global simulations have driven resolution to even smaller scales. Modeler Hiroaki Miura and colleagues at the Frontier Research Center for Global Change in Yokohama, Japan, have been running a model called NICAM—Nonhydrostatic Icosahedral Atmosphere Model—on the Earth Simulator at resolutions of 7 and 3.5 kilometers. That is nearly fine enough to resolve individual clouds. When run without convective parameterization, the 7-kilometer-resolution version of NICAM showed signs of being less sensitive than a lower-resolution model to rising greenhouse gases.

The new high-resolution work is producing intriguing hypotheses, says Mahlman. But he and others still have reservations. “Is new science being produced or just really cool pictures?” he asks. With computing resources growing exponentially and staffing not, he says, computer power might overwhelm the available brainpower. All the more reason to remember that a model—no matter how super—is only a model.

15. # Running Out of Water--and Time

1. John Bohannon

Geography, politics, and war combine to make the Gaza Strip a worst-case scenario for water-resource planners

RAFAH—You can almost hear the collective sigh of relief as the angry sun sets over this dusty city on Gaza's Egyptian border. This is when five of Ali Abu Taha's sons arrive, unwinding their kaffiyehs and gathering around the charcoal fire where a pot of tea is already boiling. The unprecedented visit of a foreign guest calls for a demonstration of the hospitality for which the Bedouins are famous. The seat of honor is offered, and some of the family's most valuable possessions are laid out on the carpet for display: a battered old AK-47 rifle and several bottles of home-filtered water. The gun is a family heirloom that rarely sees light, but the water is indispensable. “The filter cartridges are very expensive and hard to get into Gaza,” says one of the sons, Mohammed, “but this one should hold up for another month, insha' Allah.” Not only does it provide the drinking water for Abu Taha's clan—about 100 people, a third of them his grandchildren—but by enabling them to bottle and sell water to neighbors, it provides one of their few sources of income.

“I don't recommend drinking too much of this,” says Mohammed as he fills a glass with unfiltered water from the tap. One sip of the pongy brine is enough to understand why. As a general rule, the farther south one goes in Gaza, the worse the water becomes, and Rafah is the end of the line. The Palestinian Authority issues warnings from time to time urging the public to buy bottled water, especially for the very young or elderly. But for the average Gazan—with an annual income of $600—a$1 gallon of water is a luxury.

For Abu Taha, who grew up as a Bedouin in the nearby Negev desert, making efficient use of scarce water resources is nothing new. The problem is that the 1.4 million people crammed into the Gaza Strip—most of them the children of refugees who fled their homes in the 1948 and 1967 Arab-Israeli wars—depend on a shallow aquifer for water. But year by year, that source is becoming more contaminated by salt and pollution. Most wells already produce water that is nonpotable by standards set by the World Health Organization.

Water scarcity is a perennial problem in the region, but nowhere is it worse than in Gaza. “It is a microcosm of the entire Middle East,” says Eric Pallant, an environmental scientist at Allegheny College in Meadville, Pennsylvania, who has collaborated with both Israelis and Palestinians on water problems. “If you can figure out how to make water sustainable there, then you can do it anywhere.” Several Gaza water projects have been planned by donor countries in recent years, including state-of-the-art wastewater treatment and desalination plants, but all have fizzled due to security concerns and sanctions slapped onto the new Hamas-led Palestinian government. Israel's withdrawal of settlers and troops from Gaza last year is a bittersweet victory for the Palestinians. Although they are fully in control of Gaza's water for the first time, they must now scramble to save it before it becomes irreversibly contaminated.

## Water woes

It is a tense first day on the job for Mohammad Al-Agha, the Hamas minister of agriculture. Like a thunderstorm that never quite arrives, Israeli artillery pounds the landscape to the north where Palestinian militants have been launching rockets over the border. After a brief welcome party in his new Gaza City office, Al-Agha, a geologist from nearby Islamic University, and the small group of experts responsible for managing Gaza's water resources meet with Science to discuss their plans. The conversation is interrupted twice when fighter jets scream overhead and strike nearby targets with missiles, causing the building to shudder.

At a glance, the Gazans' water woes seem insurmountable. The only natural fresh source available is the coastal aquifer, a soggy sponge of sediment layers that slopes down to the sea a few dozen meters beneath their feet (see figure). Its most important input is the meager 20 to 40 centimeters of annual rainfall that sprinkles over Gaza's 360-square-kilometer surface—about twice the area of Washington, D.C.—giving between 70 and 140 million cubic meters (MCM) of water per year. Most of that water evaporates, but between 20 and 40 MCM penetrates the sandy sediment to feed the aquifer. Another 15 to 35 MCM, depending on whom you ask, flows in under the border from Israel, while irrigation and leaky pipes are estimated to return 40 to 50 MCM, for a total annual recharge of 75 to 125 MCM.

The aquifer's only natural output is the 8 MCM per year that should exit into the Mediterranean, providing a crucial barrier against the intrusion of seawater. So if no more than about 100 MCM were tapped from the aquifer per year, it could last forever. But Gaza's 4000 wells suck out as much as 160 MCM yearly, says Ahmad Al-Yaqoubi, a hydrologist who directs the Palestinian Water Authority. This estimated 60-MCM annual water deficit is why the water table is dropping rapidly and already reaches 13 meters below sea level in some places. Saltwater from the Mediterranean as well as deeper pockets of brine get sucked in to fill the gap. “The saltwater intrusion is well under way,” says Al-Yaqoubi, “especially in the coastal areas and to the south.” About 90% of wells already have salinity exceeding the WHO-recommended maximum of 250 parts per million (ppm). The accelerating rate of saltwater intrusion alone could make the Gaza aquifer unusable within 2 or 3 decades, according to a 2003 report by the United Nations Environment Programme.

But there may be far less time on the clock. The aquifer is also mixing with a cocktail of pollutants from Gaza's sewage and agriculture. “Besides salt, our number-one contaminant is nitrate from solid waste and fertilizers,” says Yousef Abu Safieh, an environmental scientist based in Gaza City who heads the Palestinian Environmental Quality Authority. The maximum safe concentration of nitrate according to WHO is 45 ppm. “In our sampling, we find that most wells have about 200 ppm, and wells close to agricultural runoff can even hit 400,” says Abu Safieh. Two Palestinian governmental studies led by Abu Safieh point to patterns of disease matching the distribution of water contamination. The higher the salinity of local water, the higher the incidence of kidney disease, he says, and nitrate concentration correlates with Gaza's high incidence of blue baby syndrome: a loss of available oxygen in the blood that can cause mental retardation or be fatal.

It is the job of a water utility to clean up such contamination and make sure that safe water comes out of the tap, but there is no such unified utility in Gaza. Instead, the strip is covered by a patchwork of fragmented water infrastructure. Gaza's three wastewater treatment plants are far from adequate. The largest, south of Gaza City, was designed to treat 42,000 cubic meters per day—the amount produced by 300,000 people—but now faces a daily inflow of more than 60,000 cubic meters, says Al-Yaqoubi: “This has overwhelmed the biological step of the treatment process.” As an emergency measure to prevent sewage from overflowing, barely treated wastewater is now piped to the coast, where the dark gray liquid can be seen, and smelled, flowing along the beach. Meanwhile, the 40% of Gazans without access to a centralized sewage-disposal system contribute to the burgeoning cesspits. A 40-hectare lake of sewage that has formed in northern Gaza is a menace to people at the surface and the aquifer beneath.

These threats to the water supply are serious, says Al-Yaqoubi, but “water scarcity is of course the problem that will never go away.” Considering that crop irrigation gobbles up 70% of Gaza's water and fertilizers contribute most of the nitrate contamination, firmer control of agriculture by Al-Agha's ministry seems like a necessary first step in saving the aquifer from ruin. “The problems continue to spiral,” says Mac McKee, a hydrologist at Utah State University in Logan, who has collaborated with Gazans for the past 10 years, because “the Palestinian Authority has not succeeded in applying effective controls on well-drilling and pumping.” About half of Gaza's wells have been dug illegally, mostly by farmers to irrigate small plots of cropland.

“If you try to tell farmers to stop using their wells, they come out with guns,” says Ehab Ashour, a water engineer who works for international development agencies in Gaza. And with the struggle for power intensifying between the Hamas and Fatah leaderships, the prospect of better enforcement seems dimmer than ever. For his part, Al-Agha says a crackdown on well-digging isn't even on the table. “We can't do this from an economic standpoint,” he says. “Over 60% of people here are farming. We are all locked into this jail, so we have to grow our own food and at the same time try to produce something we can export.”

Asking families in Gaza to use less water is also “out of the question,” says David Brooks, an environmental scientist who was an adviser during the Israeli-Palestinian water negotiations—a mandate of the Oslo Peace Accords—until they collapsed in 2003 and is now at Friends of the Earth in Ottawa, Canada. Average daily domestic water consumption in Gaza is about 70 liters per person—used not only in homes but also hospitals, schools, businesses, and public institutions—whereas 100 liters per capita per day is the generally agreed minimum for public health and hygiene. (By comparison, average consumption in Israel is 280 liters per day.) So the only way forward is to secure new sources of fresh water and make existing sources stretch farther, says Abu Safieh. There are several strategies for doing this, he says, “and we are pursuing all of them.”

## Making more with less

If you stand on any hill in Gaza and look west, a tantalizing source of water shimmers into view. If only the salts could be efficiently removed, the Mediterranean is a virtually limitless supply for desalination plants. Indeed, this very water is feeding some of the world's most advanced facilities less than an hour's drive up the coast in Israel (see Tal Perspective, p. 1081).

For any long-term solution in Gaza, “desalination will be absolutely necessary,” says McKee. A desalination plant capable of providing Gaza with 60 MCM of drinking water per year was part of a plan drawn up by the United States Agency for International Development (USAID) in 2000. Money to build the $70 million plant, along with$60 million to lay down a carrier system to pipe the water across Gaza, was ready to go from USAID when the second intifada broke out just months later, stalling the project. It was officially frozen in 2003 after a bombing killed three members of a U.S. diplomatic convoy in Gaza.

Besides producing more drinking water, the priority is to deal with Gaza's sewage, says Al-Yaqoubi, not only to prevent a public health disaster but also to recycle some of the precious water back into the system. A trio of wastewater treatment plants that could handle Gaza's entire load has been promised by USAID, the World Bank, Germany, Finland, and Japan, but “nothing has happened,” he says, because of the Hamas election victory.

In relation to stretching the current water supply farther, there is one positive legacy of Israeli occupation in Gaza. By working on Israeli farms, “we have become very comfortable with new technologies,” says Al-Yaqoubi. In spite of the official freeze on international aid to the Palestinian government, projects aiming to improve farming in Gaza “are ongoing by many donors,” he says. The most important is drip irrigation, delivering water directly to roots through a network of tubes. Coupling this with a computerized system that automatically pumps just enough water from a well to meet the plants' daily needs can make irrigation up to 70% more efficient over the long run.

But for the immediate crisis, the country best placed to help Gaza may be Israel. Before the taps were shut this year after Hamas was elected, 5 MCM per year of drinking water was being piped into Gaza by Mekorot, the Israeli national water company, and an additional 5 MCM had been agreed. That water does not come free, but it is nevertheless a freshwater source separate from the ailing aquifer.

“We know how serious the situation is in Gaza,” says Saul Arlosoroff, a member of Mekorot's board of directors and a former Israeli deputy water commissioner. “The first priority is to get these people enough clean drinking water, and the second is to prevent salinity from irreversibly destroying their soil.” Arlosoroff says Israelis and Palestinians working in the water sector have a special relationship. “We understand each other, and we know that these problems require cooperation,” he says, “but the atmosphere between Gaza and Israel is worse now than at any time in our history.”

Across the border, Abu Safieh is similarly disappointed. “There was a time when I could talk with my Israeli counterpart constructively about our environmental problems,” he says, but he has not had any contact in years. Al-Agha says he plans to turn to Egypt for help. For importing and exporting, as well as perhaps for obtaining the abundant electricity needed to desalinate water, he says, “our hope is to the south.”

The present turmoil also prevents what Brooks calls “the easiest and best solution” to Gaza's environmental problems: reducing the number of people living there. “Gaza can't sustain that population, and any real solution will require people to leave,” he says. Most Gazans “will never give up hope of returning to their homes,” says Abu Safieh, but for now, “we will work to make the best of the bad situation.”

16. # Desalination Freshens Up

1. Robert F. Service

Cheaper materials, more efficient equipment, and some promising new approaches could make large-scale extraction of clean water a major force in the battle against global thirst

Efforts to provide clean, fresh water for the world's inhabitants seem to be moving in the wrong direction. According to the World Health Organization, 1 billion people do not have access to clean, piped water. A World Resources Institute analysis adds that 2.3 billion people—41% of Earth's population—live in water-stressed areas, a number expected to climb to 3.5 billion by 2025. To make matters worse, global population is rising by 80 million a year, and with it the demand for new sources of fresh water.

Wealthy countries are by no means immune. In arid parts of the United States and many other countries, groundwater resources are already dwindling, and supplies that remain are becoming increasingly brackish. Environmental concerns have drastically limited the building of new dams in recent decades. In many areas, “we are already wringing all the water out of the systems that they have,” says Thomas Hinkebein, a geochemist at Sandia National Laboratories in Albuquerque, New Mexico. “[We] have to start developing new sources of water.”

Such concerns have made desalination—the process of removing salts and suspended solids from brackish water and seawater—a fast-growing alternative. According to a 2004 report by the U.S. National Research Council, more than 15,000 desalination plants now operate in more than 125 countries, with a total capacity of turning out 32.4 million cubic meters (m3) of water a day, about one-quarter of the amount consumed by U.S. communities each year. With numerous areas around the globe facing long-term severe water shortages, “I don't see [the demand for desalination] slowing down any,” says Michelle Chapman, a physical scientist at the U.S. Bureau of Reclamation in Denver, Colorado, and co-chair of a desalination research program funded by the U.S. Office of Naval Research.

But desalination faces its own problems. The two technologies at the heart of conventional desalination plants—evaporation and reverse osmosis (RO), which involves pushing water through a semipermeable membrane that blocks dissolved salts—both require huge amounts of energy. A typical seawater RO plant, for example, requires 1.5 to 2.5 kilowatt-hours (kWh) of electricity to produce 1 m3 of water; a thermal distillation plant sucks up to 10 times that amount. Countries such as Saudi Arabia may be able to afford to run such facilities, but for most other countries, the cost was already too high even before oil prices went through the roof.

Yet despite those worrisome trends, the prospects for desalination have brightened considerably in the past few years. New engineering designs have slashed the cost of desalination plants, particularly membrane-based RO systems, and new technologies as diverse as nanotechnology and novel polymers are expected to drive down operating costs in the years ahead. “There is a huge body of research going on,” says Hinkebein, who also oversees a broad collaboration on charting a future road map for desalination technology. “Progress has been a bit incremental for a number of years,” adds Anne Mayes, a materials scientist and membrane specialist at the Massachusetts Institute of Technology (MIT) in Cambridge. “But now new opportunities are starting to open up. We're going to see some very different technologies being developed in the near future.”

## Faster, cheaper, better

Desalination has ancient roots. Aristotle and Hippocrates described the process of evaporating salt water to make fresh water in the 4th century B.C.E. In modern times, desalination kicked into gear in the early 20th century. By the mid-1950s, hundreds of desalination plants were on line. Most were based on evaporation, a technique that continues to turn out about half of the globe's desalinated water. Although typically more expensive, the technique remains popular in the Middle East, largely because it is well-suited for dealing with the high levels of salts and suspended solids in the water of the Persian Gulf.

Elsewhere, most new plants being built today use RO because the process requires far less energy. As its name implies, the technology reverses the process of osmosis: the natural tendency of water molecules to flow through a semipermeable membrane to dilute a chemical solution on the other side, in this case seawater. To force water molecules to travel the other way requires pressure—at least 3 megapascals (MPa), but more typically 6 MPa—which in turn requires electricity. Historically, an RO plant has used 10 to 15 kWh of electricity to produce 1 m3 of fresh water.

Between 1980 and 2000, improvements in pumps and other equipment in RO plants dropped the amount of energy needed to produce fresh water by about half, says John MacHarg, CEO of the Affordable Desalination Coalition (ADC), a San Leandro, California-based group of 22 municipalities, state agencies, and desalination companies looking to improve seawater desalination technology. Since 2000, energy requirements have again dropped by about half, thanks to new energy-recovery devices called isobaric chambers that redirect pressure from the waste brine to low-pressure incoming water. These devices recover up to 97% of the energy. Their resounding success has already made them an integral part of the newly designed desalination plants. In one such plant, which started up last fall in Ashkelon, Israel, for example, isobaric chambers have helped lower the cost of desalinated water to \$0.527 cents per m3, among the cheapest ever by a desalination facility.

Such price drops are now widely expected to continue. By combining energy-recovery devices with new low-pressure membranes and other commercially available advances, this spring ADC members set a new world record for low-cost desalination, dropping the energy needed to 1.58 kWh per m3 of water produced. At that rate, a seawater desalination plant could supply a typical U.S. household with fresh water for the amount of power needed to light an 80-watt light bulb, MacHarg says. That figure, he adds, could change the equation of how to supply places such as southern California with water, because it takes the same amount of energy to pump freshwater from northern California to Los Angeles.

## Juggling act

Still, MacHarg and others say there is plenty of room for improvement, particularly with the membranes at the heart of RO systems. “Basically, [membrane] technology hasn't changed much in the last 40 years,” says Thomas Mayer, a desalination expert at Sandia. “The polymer films are fairly standard nylon-type materials that work reasonably well.”

These membranes need to accomplish two somewhat contradictory goals at the same time: They must allow water to flow through at a high rate while blocking nearly all dissolved salts. Conventional membranes are made of plastics called aromatic polyamides, which prevent 99.9% of salt ions from passing through but still allow a reasonable flux of water. The plastics can strike the balance because they contain charged chemical groups that repel salt ions, while under high pressure the neutral water molecules actually dissolve into the continuous membrane sheet and pass through to the other side.

The aromatic polyamides were initially so much better than their predecessors that researchers have only recently begun to look for ways to improve them, says Benny Freeman, a polymer chemist at the University of Texas (UT), Austin. They do have big drawbacks: They require high pressure, and therefore energy, to push the water through, and they are also prone to biofouling, in which thin films of organic material coat the surface of the membrane and block water from going through.

One simple way to stop fouling is to add chlorine, much as municipal water treatment plants do to fight pathogens. Unfortunately, chlorine attacks the nitrogen-hydrogen bonds that hold polyamide polymers together, opening holes that allow salts to wiggle through the membranes. So Freeman's group, in conjunction with chemist James McGrath of Virginia Polytechnic Institute and State University (VT) in Blacksburg, has recently begun developing new chlorine-resistant polymers. The researchers have designed membranes made of sulfonated polysulfones, which lack the vulnerable N-H bonds that chlorine attacks. Other researchers had previously tried to add sulfonated groups to membrane polymers after the polymers were already made, McGrath says, an approach that made them difficult to reproduce, and they often degraded quickly. Instead, the UT-VT team created sulfonated polymer building blocks that they then linked together in a more tightly controlled manner.

The strategy seems to be working. In May at a meeting of the North American Membrane Society in Chicago, Illinois, Freeman reported that the UT-VT group's new membranes transmit more water than traditional aromatic polyamides do while screening 99% of the salt ions. Whereas conventional membranes begin to break down after 8000 hours of exposure to chlorinated water, the new membranes show no signs of decay—meaning it may be possible to make membranes that don't have to be replaced. Freeman and his team are now tweaking the formula for the plastic in hopes of improving the 99% salt-rejection figure.

Mayes is taking a different tack to improve desalination membranes. Her group at MIT creates membranes from polymer molecules reminiscent of tiny combs. In this case, the combs' “backbone” is made up of water-fleeing molecules such as polyvinylidene fluoride (PVF), a common membrane component. Attached to this backbone are myriad “teeth” composed of short water-attracting polyethylene oxide (PEO) segments. As the polymer forms, these two different segments try to separate from one another, just as the water-fleeing and water-loving properties of oil and water cause them to separate. The result is that the PEO segments circle around one another, creating an array of tiny 2-nanometer-diameter pores in the PVF membrane.

The resulting membranes pass water with a very high flux. They also resist fouling, because the PEO units bind with water molecules so strongly that they give biomolecules few handholds to attach themselves to.

For now, however, the pores are still big enough that salt ions readily flow through. The membranes could still be useful as pretreatment filters to remove larger suspended solids before the water is sent to the RO filter, Mayes says. But she hopes to improve their salt-trapping ability, either by adding charged groups to the backbone portion of the molecules to repel charged ions or by shortening the PEO side chains to make the pores smaller.

Olgica Bakajin, a physicist at Lawrence Livermore National Laboratory in California, is also looking to tiny pores to improve her team's membranes. Bakajin and her colleagues have spent years studying how fluid moves through nano-sized devices. Their calculations showed that water would likely whisk quickly through the smooth, hollow centers of carbon nanotubes, each of which is only 1 or 2 nanometers across. So they decided to make a filter from an array of 89 tiny membranes, each 50 micrometers on a side and consisting of a silicon nitride film perforated by thousands of carbon nanotubes. In a paper published in the 19 May issue of Science (p. 1034), Bakajin and her team reported that it took only a single atmosphere of pressure (or 100 kPa) to get water to cross their membranes, although in this case they were tested with fresh water rather than salt water. “We thought our membrane had ruptured,” Bakajin says. But it hadn't, and when they studied their pores in detail, they found that they were transporting 1000 times more water than expected.

Sandia's Mayer says he is “very excited” about the new result: “We're sorry we didn't do it first.” Bakajin acknowledges that she and her colleagues still don't know why nanotubes are such good water transporters. But if carbon nanotube-based membranes can be scaled up and made to exclude salts—both of which are big unknowns at this point—it could enable desalination facilities to sharply reduce the amount of energy required to purify water.

Other low-energy desalination techniques are also on the horizon. In one, called forward osmosis, researchers try to harness normal osmotic pressure for making freshwater. They start with freshwater and seawater separated by a membrane and spike the freshwater side with a high concentration of sugar. Freshwater flows through the membrane as it works to dilute the high sugar concentration. “The problem is that you end up with sweetened water,” says Menachem Elimelech, an environmental engineer at Yale University. In place of sugar, Elimelech and colleagues have been experimenting with dissolved ammonium salts, such as ammonium bicarbonate. The salts draw fresh water through the membrane without the need for added pressure. Then, by heating the solution to 58øC, Elimelech's team causes the dissolved salts to form ammonia and carbon dioxide gases, which are easily separated from the water. “If we can use waste heat, the process can be very economical,” Elimelech says.

Two other technologies are also looking to waste heat and very cheap starting materials to make easily affordable desalination systems. One, dubbed “dewvaporation,” is the brainchild of James Beckman, a chemical engineer at Arizona State University, Tempe. The other, called membrane distillation, has been pioneered by Kamalesh Sirkar, a chemical engineer at the New Jersey Institute of Technology in Newark. Beckman's dewvaporation apparatus vaporizes water in one compartment, sending it over a barrier to another where it condenses; Sirkar's membrane distillation passes the water vapor through pores in a membrane that liquid water or larger ions cannot traverse. Both processes are well on their way to proving themselves in the real world. Sirkar's membrane-distillation system is now being put through its paces by United Technologies in East Hartford, Connecticut, and dewvaporation is being evaluated as an option to create freshwater by the city of Phoenix, Arizona.

Beckman and Sirkar say the advantage of their systems is that they can work with a variety of waste-heat sources, such as steam from industrial plants or even solar energy. That versatility could make them especially advantageous for developing countries. Chapman notes that such systems can be particularly useful as add-ons to conventional RO systems. RO plants typically convert only about 50% to 70% of salt water to fresh water and must treat and dispose of the waste brine—a costly process. Because these novel systems can potentially evaporate all the water and leave only solid salts behind, they promise to save governments a lot of money, Chapman says.

It's unclear whether such novel systems will be able to compete with industrial-scale RO and thermal desalination plants. But Chapman points out that the needs of different communities vary widely when it comes to water, depending on the quality of the water source among other factors. “All water sources are different,” Chapman says. “So there will probably be a place for all of these technologies”—and no doubt plenty of thirsty users as well.