# News this Week

Science  16 Nov 2012:
Vol. 338, Issue 6109, pp. 868
1. # Around the World

1 - The Hague
A Place for All at The Climate Science Table
2 - Washington, D.C.
USAID Launches New Science Program
3 - Berlin
Biomedicine Gets Boost
4 - London
Launching New Money Into Space
5 - Sacramento
Rejecting GM Food Labels, Backing Education

## The Hague

### A Place for All at The Climate Science Table

The Dutch government has created an online forum where “climate experts representing the full range of views” can discuss the hottest topics in climate change. The public can provide running commentary.

The site, launched this week at ClimateDialogue.org, began by tackling Arctic sea ice. Three respected American climate scientists will debate the causes of sea-ice decline—global warming and natural variability lead the list—and when the Arctic Ocean could be ice-free. The scientists' estimates “range from 2016 to the end of the 21st century, or even later,” a Climate Dialogue statement said.

The spread of opinion is deliberately broad. ClimateDialogue.org is one of several government projects the Dutch parliament has requested to “involve climate skeptics in future studies on climate change,” another statement explained. An advisory board of six scientists and a retired business executive will advise an editorial staff and “guard the neutrality of the platform,” the site says.

## Washington, D.C.

### USAID Launches New Science Program

The U.S. Agency for International Development (USAID) last week announced major awards at seven universities in the United States and abroad to support “development labs” that will design innovative, low-cost approaches to improving health and reducing poverty and conflicts. The program, called the Higher Education Solutions Network, intends to invest $130 million over 5 years. Each of the seven institutions will receive grants of up to$5 million a year, with a 60% required match by the universities. As an example of the kinds of projects the program wants to encourage, USAID Administrator Rajiv Shah cited a cheap bucket filter designed at the Massachusetts Institute of Technology (MIT) in Cambridge to remove arsenic from groundwater in Bangladesh.

Pedro Sanchez, of the Earth Institute at Columbia University, says the concept of the awards is very innovative. “It's a great step forward,” he adds.

The winners are Texas A&M University; Makerere University in Uganda; MIT; Michigan State University; Duke University; the University of California, Berkeley; and the College of William & Mary. USAID intends to call for more proposals in the future. http://scim.ag/USAIDprgms

## Berlin

### Biomedicine Gets Boost

Two of Berlin's largest biomedical research centers are joining forces to form the Berlin Institute of Health (BIH), a cooperative venture that will receive at least €320 million in new funding over the next 5 years. The union of the Max Delbrück Center for Molecular Medicine and the Charité, the university clinic of Berlin's Humboldt University and Free University, will help attract top clinicians, researchers, and medical students to Berlin, says the city's mayor, Klaus Wowereit.

The new institute's organization will take shape next year, says Charité head Karl Max Einhäupl, with an international evaluation team advising BIH on how to best combine the two organizations' strengths.

BIH bends some of the strict German rules about what types of research organizations the federal government can fund. Universities are primarily funded by the Länder (states). In this case, however, the federal government will provide 90% of the €300 million budgeted for BIH between 2013 and 2018. The privately financed Charité Foundation has promised an additional €40 million over 10 years. http://scim.ag/Berlinbiomed

## London

### Launching New Money Into Space

In a speech given on 9 November at the Royal Society, Britain's chief finance minister, Chancellor of the Exchequer George Osborne, announced that the government would increase spending on space by 30%, or £60 million per year. The move comes just days before European ministers responsible for space decide the European Space Agency's (ESA's) budget and spending priorities for the next 4 years. The extra money should allow Britain's ESA delegation to make more substantial commitments to agency projects, such as the ExoMars project to send landers and orbiters to the Red Planet. NASA withdrew from ExoMars earlier this year, and ministers from ESA's 19 member states must decide at the meeting whether to form a new collaboration with Russia or go it alone.

Although the chancellor's announcement boosts Britain's ESA contribution to about €300 million annually, the United Kingdom still contributes less to ESA than Italy (€350 mil lion in 2012), France (€751 million), and Germany (€714 million). http://scim.ag/Moneyinspace

## Sacramento

### Rejecting GM Food Labels, Backing Education

After months of heated public debate and more than $50 million in campaign spending, Californians on 6 November voted against Proposition 37, which called for the mandatory labeling of genetically modified (GM) food sold in the state. Although early polls showed considerable public support for GM food labeling, 53% of voters ended up rejecting the measure. Golden State voters also backed Governor Jerry Brown's plan to save schools from drastic budget cuts. Proposition 30, supported by 54% of voters, will raise the state income tax for wealthy residents for 7 years and increase California's sales tax by 0.25%. The measure is expected to provide an estimated$6 billion annually for K–12 education and community colleges, and prevent additional cuts and tuition hikes at state universities. http://scim.ag/GMlabel; http://scim.ag/_HigherEd

2. # Random Sample

## Noted

“I give a shit, do you?” is the theme of this year's World Toilet Day (www.worldtoiletday.org), held annually on 19 November. Organized by the Water Supply and Sanitation Collaborative Council and the World Toilet Organization, the event aims to raise awareness of the 2.5 billion people around the world living without proper sanitation.

## Cellular Chaos on the Dance Floor

Molecules in a cell move and run into each other all the time. Now, a scientist and a dancer have figured out a way to model that movement—using people.

David Odde, a biomedical engineer at the University of Minnesota, Twin Cities, and Carl Flink, artistic director of the dance company Black Label Movement and head of the university's department of Theatre Arts and Dance, originally got together with the idea of presenting Odde's research in dance form: specifically, how the molecules that comprise part of a cell's internal skeleton come together and fall apart. Flink worked out how dancers could slam into each other safely—inflatable “sumo suits” and body armor were initially considered—and follow rules in a way that approximates randomness.

But the company has never performed these routines for audiences; instead, Flink and Odde use “bodystorming” to quickly try out hypotheses explaining molecular movements within cells—Odde has already rejected one idea he had proposed. “By giving specific instructions to dancers, you are forced to articulate what your hypothesis is,” he says. Programming computer simulations can take months. With dance, “we immediately get to see it play out.” The collaboration has been so successful that Odde and Flink hold weekly joint lab meetings in a dance studio and published their work online on 1 November in Trends in Cell Biology.

“We as scientists spend a lot of time thinking,” Odde says. But, when he, his students, or other scientists get into the dance, “you suddenly feel like you're in that space. You can feel it kind of in your gut, what it means to be a molecule.” http://scim.ag/bodystorm

## ScienceLIVE

ScienceLIVE returns on Thursday, 29 November, at 3 p.m. EST for a chat on the imminent “end of the world.” http://scim.ag/science-live

3. # Newsmakers

## Researchers to Head Yale University and UC Berkeley

This month, psychologist Peter Salovey and anthropologist Nicholas Dirks were picked to lead Yale University and the University of California (UC), Berkeley, respectively.

Salovey, 54, is well-known for advancing studies of “emotional intelligence,” described as the ability to monitor one's own and others' feelings, discriminate among them, and use this information to guide thinking and action. The work has been used to alter behavior, particularly in AIDS prevention, says Alan Kraut, executive director of the Association for Psychological Science. Salovey, currently Yale's provost, succeeds President Richard Levin on 30 June 2013.

Dirks, 61, currently Columbia University's executive vice president for arts and sciences and dean of the faculty, has done field research in India and Britain and has authored three books on Indian culture and history. Nominated to succeed Robert Birgeneau as Berkeley's chancellor on 1 June 2013, Dirks is expected to be approved by the UC Board of Regents later this month.

## Darwin for Congress?

Charles Darwin won support from at least 4000 voters in the 10th congressional district of Georgia thanks to an initiative headed by James Leebens-Mack, a plant biologist at the University of Georgia in Athens.

Leebens-Mack was deeply troubled by a speech that Representative Paul Broun (R-GA), who represents the 10th district in the U.S. House of Representatives, gave at an Athens church in October. Broun derided teachings on evolution, embryology, and the big bang theory as “lies straight from the pit of Hell.” Broun, a medical doctor, serves on the House Committee on Science, Space, and Technology.

Leebens-Mack channeled his outrage by setting up a Facebook page inviting citizens to vote for Darwin as a write-in candidate against Broun—who ran unopposed. Broun won comfortably, but Darwin got enough votes that Leebens-Mack says it's clear many people in the district were “not happy with antiscience statements.”

Would Leebens-Mack run against Broun himself in 2014? “I enjoy my job as a plant biologist,” he says. “It would be too big a sacrifice to give that up to run for Congress.” http://scim.ag/Darwinrep

## They Said It

“He is the latest in a long line of rulers and important people who have hired or been approached by scientists and physicians who claim to have found some kind of elixir capable of prolonging life.”

—Jennifer Rampling, a science historian at the University of Cambridge in the United Kingdom, in The Telegraph on reports that Kazakhstani scientists are developing a life-extending yogurt-based drink for the country's leader, Nursultan Nazarbayev.

## Inaugural Picks for John Maddox Prize

A Chinese science reporter and a British psychiatrist are the first to win an award, named for former Nature editor John Maddox, honoring people who have defended sound science in the face of strong opposition. The prize, sponsored by Nature and the Kohn Foundation and organized by the U.K. charity Sense About Science, comes with £2000 for each winner.

Fang Shi-min, a biochemist-turned-science journalist, won the award for exposing scandals in Chinese science and medicine on his Web site New Threads. Fang attacked supposedly rejuvenating but unproven DNA supplements and took aim at traditional Chinese medicine (Science, 8 February 2008, p. 709). In 2010, thugs hired by a urologist whom Fang had criticized attacked him with a hammer.

Simon Wessely of King's College London, the other winner, says he suffered intimidation—including death threats—and harassment for his research on chronic fatigue syndrome (CFS). Wessely demonstrated a big overlap between CFS and clinical depression and pioneered cognitive behavioral therapy as a CFS treatment, angering patient advocates who see CFS as purely physical. “I'm pleased that people recognized the pressure brought to bear on me and many colleagues,” he says.

4. Ecology

# Nearly Buried, Mussels Get a Helping Hand

1. Erik Stokstad

North America is home to a record diversity of freshwater mussels with dazzling reproductive strategies and key ecological roles. But can they withstand the hard knocks of a modern world?

Every spring, a freshwater mussel called the snuffbox emerges from gravel stream bottoms for a violent bout of reproductive deception. The females have spent months buried in the sediment, brooding thousands of larvae that require a certain host to mature. Now the mussels lie on the streambed, their shells open wide. Playing dead, they wait for just the right fish to approach.

That fish, the logperch, spends its days hunting for insect larvae and fish eggs, rummaging under small stones and empty shells. When a logperch pokes its snout inside a snuffbox (Epioblasma triquetra), the mussel snaps shut. The fish is trapped between the serrated edges. For other fishes, this mistake would be fatal, but the logperch has a reinforced skull. As the fish struggles, the mussel pumps out its larvae, which clamp their tiny shells onto the filaments of the logperch's gills. Then the mussel lets go. After several weeks of hitchhiking, the juvenile mussels drop from the gills and settle into their new habitat.

This aggressive tactic, discovered in 2003, is just one of the remarkable behaviors that freshwater mussels use to reproduce and spread upstream. Other species attract their fish hosts with lures that resemble fish eggs, crayfish, or even swimming minnows. “It's some of the most amazing mimicry in the world,” says restoration biologist Jess Jones of the U.S. Fish and Wildlife Service (FWS) in Blacksburg, Virginia. And it's a North American specialty: The continent hosts the world's greatest known assortment of mussels, 297 species, more than two-thirds of which are concentrated in the southeastern United States. Some rivers have more species of mussels than are found in all of Europe.

But freshwater mussels are in trouble. They are the most endangered group of organisms in the United States, with most of their river and stream habitats devastated by dams, pollution, and invasive species such as the zebra mussel. Thirty-five species have been declared extinct, others are likely gone, and more than 70 species are teetering on the brink. The snuffbox, for example, was put on the U.S. endangered species list this past February; biologists estimate its population has declined by 90% over the past century. This month, FWS added another eight mussel species to its list. “It's the biggest conservation crisis in the U.S. that no one talks about,” says Paul Johnson, who directs the Alabama Aquatic Biodiversity Center in Marion.

Mussel conservationists are intent on fixing the problem. They've persuaded a few dam operators to modify their water releases to improve conditions for mussels. They have also helped restore water quality in important mussel habitats. Researchers, meanwhile, are trying to solve some puzzles in mussel ecology, figure out how to culture more kinds of endangered mussels in captivity, and ramp up restoration efforts. Time is running short, says Robert Bringolf of the University of Georgia in Athens, but “hopefully we have a chance to turn things around.”

North America owes its astounding freshwater biodiversity in large part to unique geology, which has provided a stable environment that enabled mussels to thrive and diversify for 60 million years (see p. 877). Historically, expansive shoals of mussels served as habitat for other aquatic organisms. By filtering water, mussels move nutrients through the food web, supporting nearby terrestrial ecosystems as well. The result: Rivers and streams with a greater number of mussel species tend to have richer algal and insect communities than those with fewer species, Caryn Vaughn of the University of Oklahoma, Norman, and colleagues concluded in a paper published in Ecology last month.

People have also long benefited from mussels. Massive middens hint at the untold numbers harvested by Native Americans for food. In the mid-19th century, a bustling industry sprang up to collect mussel shells for making buttons. Nowadays, workers grind mussels into “seeds”—bits of shell—that are shipped to Asia and placed into Pacific marine oysters to create cultured pearls. Most scientists, however, don't think that these activities put many mussel species in jeopardy of extinction.

### Multimedia

What has caused serious harm is widespread fragmentation and loss of habitat. Mining and deforestation, which polluted streams and clogged them with sediment, were already problems by the late 19th century. The worst trouble started in the early 1900s, when engineers built locks and dams in large numbers. These efforts culminated in the gargantuan dams constructed across the southeastern United States by the Tennessee Valley Authority (TVA) in the 1930s and '40s. Most mussel species can't live in the slow, muddy water and silty bottoms of the reservoirs formed by these dams. Nor can half the fish species that mussels need as hosts for their larvae.

Sometimes extirpation is delayed. Populations can persist, because the adults live for many decades. They might seem healthy, but they can't produce young, impaired either by pollution or because the fish hosts are gone. “It's an insidious decline,” says David Strayer of the Cary Institute of Ecosystem Studies in Millbrook, New York. The population crash can come “breathtakingly fast” once these older mussels start dying.

Researchers are discovering more about these invisible threats. Lab studies show that mussels are sensitive to a number of common but poorly regulated water contaminants, such as the surfactants in the common herbicide glyphosate. In a detailed field study, Strayer and Heather Malcom, also at the Cary Institute, found that the absence of juveniles was highly correlated with ammonia—likely from fertilizer or manure—in the sediment where the mussels burrow. Spikes in ammonia concentrations “may be responsible for widespread declines of freshwater mussel populations, especially in agricultural areas,” they reported in Ecological Applications in September. Some ecologists suspect that the current level permitted in surface water by the U.S. Environmental Protection Agency is dangerous for mussels.

The accelerating disappearance of mussels “really is a strong statement about what we've done to rivers,” Bringolf says. In the Mississippi River Basin alone, perhaps less than 10% of the original habitat of endangered mussels remains unaltered by dams.

## Positive steps

The situation is not entirely bleak. Once researchers began to understand the threats facing mussels, they were able to argue for major modifications of dam operations—helped by the legal hammer of the Endangered Species Act. Two decades ago, for instance, researchers couldn't find any endangered Cumberland monkeyface mussels in Tennessee's Duck River, which is controlled by the 855-meter-wide Normandy Dam. One problem was chronically low oxygen levels in the river below the dam. In 1991, TVA began to address that issue by blowing air into underground sluices as they released water from the reservoir—essentially creating a giant bubbler. Within a decade, researchers counted tens of thousands of mussels throughout 50 kilometers of river. “It shows you that flow restorations work and that we can recover some of these animals,” Johnson says.

Conservationists have also encouraged efforts to improve water quality. Federal and state programs pay landowners to use best management practices that can reduce polluted runoff, including planting trees along stream banks and fencing out cattle. Organizations such as the Nature Conservancy have stepped in, purchasing land to protect important mussel habitat, such as the Clinch River in Virginia and Tennessee, and collaborating with farmers to restore it.

The most urgent work is to prevent the extinction of highly endangered mussels. Their small populations are vulnerable not only to chronic problems but also to freak accidents. For example, in the largest mass mortality recorded in the history of the U.S. Endangered Species Program, a 1998 spill from a chemical tanker truck killed more than 18,000 mussels in the Clinch River system. Some 750 of the dead were members of three endangered species: the tan riffleshell, the purple bean, and the rough rabbitsfoot. In 2003, the federal government settled with the trucking company for $3.8 million in damages. Relying in part on funding provided by such fines, biologists have established hatcheries for mussels—and their specialized fish hosts—to help boost wild populations. There are now 15 mussel farms, run with state and federal funds; the newest and biggest is the$3 million Alabama Aquatic Biodiversity Center, which opened in 2010. This facility alone has the capacity to produce more than a million animals a year, which are used to establish new colonies—a kind of biological insurance policy against local disasters.

In late September, for example, a team from FWS and the Virginia Polytechnic Institute and State University (Virginia Tech) in Blacksburg drove to the Powell River in Tennessee for their largest-ever release of oyster mussels and Cumberlandian combshells, two endangered species propagated in Virginia Tech's Freshwater Mollusk Conservation Center. Water quality in the Powell has slowly improved over the past decades, but 13 of the 35 species of mussels in the river are still endangered.

Working under the shade of hickory trees, field assistants in hip waders carried a large cooler full of mussels to the muddy riverbank. They splashed in and scattered several thousand juveniles. Meanwhile, lab manager Dan Hua carefully tucked 27 snuffbox mussels into the gravelly riverbed for the first time; the lab has only recently figured out how to culture this endangered species. “The most exciting thing is that our babies are home now,” she said with a grin.

## Boosting populations

Cultivating mussels is not easy, and it requires some sleuthing. If the preferred fish host is not known—often the situation with endangered species—researchers must become matchmakers, trying to find the right partners by testing various species in the lab. Next, researchers take female mussels into the lab, where they remove the larvae and then add them to the gills of host fish. Even more challenging is figuring out the right conditions for the subsequent care of the juveniles, Johnson says. In some systems, these 250-micrometer mussels can fall prey to tiny flatworms and other predators in the tanks, with mortality rates of up to 80% or more in the first 2 months. Staff members must change the water and sediment regularly to prevent predators from booming. “It's like farming; you can't take a day off,” Jones said recently, as he checked the gurgling tanks in his cavernous center.

Building on early work at Virginia Tech by fisheries biologist Richard Neves, researchers there and elsewhere have further improved propagation equipment and techniques. In the last 5 years or so, they have become adept at growing more and larger mussels. That's important because bigger juveniles have a higher chance of surviving in the wild. “It's opened up population restoration,” says M. Christopher Barnhart of Missouri State University in Springfield, who has developed compact culture systems that deliver more feed to the juveniles and are widely used for rearing mussels. Larger mussels can also be tagged to better monitor success rates. Research at Virginia Tech by Hua and graduate student Caitlin Carey suggest that mortality rates in the wild for the bigger animals are less than 10% a year.

Two concerns with propagation, however, are unanticipated ecological impacts and inadvertent mixing of unidentified stocks; genetic background checks are just beginning. In addition, propagation, driven by the requirements of the Endangered Species Act, exclusively targets the most imperiled mussels. “The rarer a species becomes, the more attention it gets,” Barnhart explains. That's why many biologists hope that common species can also be protected by better understanding and highlighting their benefits to ecosystems and humans. “The direction that we're trying to go in our research is to put monetary values on these services that mussels are providing,” Vaughn says. For instance, mussels filter out phytoplankton, bacteria, and algae. That could be a good reason for a dam operator to keep water flowing in rivers during droughts, for instance, or to restore damaged rivers (so mussels can help keep them clean) rather than build an expensive new water treatment plant. It can be “cheaper to do the cleanup work than keep treating the water,” Johnson says.

Whether or not mussels will ever be able to pay their own way to survival, their astonishing mimicry and reproductive talents inspire researchers to better understand and care for this hidden diversity. “Once I realized how highly evolved mussels really are, and that they are better at catching fish than I am, I didn't have anything but respect for them,” Bringolf says. “This is what draws people in.”

5. Ecology

# The Evolutionary Allure of Mussels

1. Erik Stokstad

Genetic studies have revealed that mussel diversity in North America is even higher than past studies suggested, meaning species that were once thought to be widely distributed could in fact be imperiled.

North America's marvelous variety of mussels is due to a fortuitous combination of geology and climate. In the southeast, where the diversity is highest, watersheds have remained essentially unchanged for millions of years. The many isolated rivers provided room for new species and constant flows that prevented extinctions, unlike many waterways in Africa and Australia that vanish in severe droughts. The southern United States also escaped glaciation—unlike the northern United States and Europe, which has only about a dozen species of mussels. Rivers in the tropics, meanwhile, tend to lack nutrients and have too much silt for many mussels.

Over the past decade, genetic studies have revealed that mussel diversity in North America is even higher than past studies suggested, says fisheries biologist Wendell Haag of the U.S. Forest Service in Oxford, Mississippi. Widely separated populations that were once lumped into a single species because of their similar shell morphology, for example, are now understood to belong to multiple taxa. That matters: “A lot of species that we thought were widely distributed will turn out to have very restricted ranges and be highly imperiled,” Haag says.

The exotic lures that some of these mussels use to attract their fish hosts are apparently unique to North America, although mussel biology is much less known in Asia. How the mussel-fish collaboration evolved is a mystery. In 2008, Haag and M. Christopher Barnhart of Missouri State University in Springfield proposed a scenario in the Journal of the North American Benthological Society. Mussel larvae secrete threads, they noted, which help them stay afloat. Such threads may have become snagged on passing fish—giving some early mussels a benefit by carrying them into new habitat.

Another clever mussel reproductive strategy is producing larvae that appeal to hungry fish, giving the larvae a chance at hitching a ride on their gills. This approach may have started with ancestral mussels that, like some modern species, released millions of larvae without trying to attract a host fish. Over time, species that released their larvae in clumps called conglutinates, some of which are filled with colorful sterile eggs, may have gained an advantage because the clumps looked tasty.

The clumps may also have been a steppingstone to the more sophisticated strategy found in two groups of a diverse mussel tribe named Lampsilini. One group, which includes the fluted kidneyshell (Ptychobranchus subtentum), makes membrane-wrapped conglutinates that resemble fish eggs or insect larvae. Species in the second group, such as the orangenacre mucket (Lampsilis perovalis), spin out a “superconglutinate” that remains tethered to the mussel by a clear cord that is up to a meter long. It looks like a minnow swimming, complete with eyespots and countershading.

Some mussels have evolved even fancier lures by modifying their mantle. The rainbow mussel (Villosa iris) has one that resembles a crayfish, which it moves by rocking its shell back and forth. Wavy-rayed lampmussels (Lampsilis fasciola) each use one of three kinds of lures, perhaps to catch fish that have learned to avoid their neighbors. No matter, there's a sucker born every minute.

6. Climate Change

# Winds of Change

1. Jane Qiu*

Antarctica's fate is not as simple as that of an ice cube melting in the sun, scaled up a trillionfold.

PALMER STATION, ANTARCTICA—To Jennifer Blum, the empty nests on Torgersen Island are a harbinger of doom. The rugged outcrop is home to one of the largest colonies of Adélie penguins on the Antarctic Peninsula, a crooked sliver of land flanked by dozens of islands that reaches north toward the tip of South America. But the Adélies here are fading fast. There are fewer than 2000 breeding pairs, a quarter of the number found in the 1970s. Each spring, Blum, an ornithologist with Polar Oceans Research Group, a nonprofit in Sheridan, Montana, and her colleagues monitor colony size and breeding success. “You see a lot of newly abandoned nests every year,” she says. “The changes have been staggering.”

Blum's group has charted similar declines on nearby islands. She and others blame climate change. On the Antarctic Peninsula, the mean annual temperature is –3°C, more than 2° warmer than it was 50 years ago. Over the past 5 decades, winter temperatures have risen a staggering 6°C, or five times the global average. Roughly nine out of every 10 glaciers on the peninsula are retreating, says Hugh Ducklow, director of the Palmer Long-Term Ecological Research Station here on the western coast of the Antarctic Peninsula. Coastal ice persists only 5 months a year, three months fewer than 30 years ago.

Warming has warped the peninsula's food web. But “global warming is only part of the story,” says David Thompson, a climate researcher at Colorado State University in Fort Collins. An unsung force now shaping the frozen continent's future is changing wind patterns. Retreating sea ice and stronger winds have caused seawater to mix more deeply, a process that churns sunlight-dependent phytoplankton into the ocean's depths. As a result, phytoplankton biomass has declined by 12% over the past 30 years. Higher on the food chain, that means fewer krill and fish larvae. These creatures are also getting hammered by the loss of sea ice, which hides them from predators.

More crucially, the complex interplay between air, sea, and ice has emerged as a central theme underlying climate change in Antarctica. Shifting wind patterns and corresponding ocean changes can explain climate responses across the continent. “It's quite a fabulous piece of climate science,” says Robert Bindschadler, a glaciologist at NASA Goddard Space Flight Center in Greenbelt, Maryland. “It shows how the atmosphere is connected to the ocean, and how they impact the ice in a beautiful chain of events.”

“People used to think Antarctica responds to global warming like a giant ice cube”—with rough uniformity—says Amelia Shevenell, a paleoclimatologist at the University of South Florida, St. Petersburg. “We now know this is not the case.”

## Ghosts in the machine

Antarctica's climate is strongly affected by westerly winds that buffet the Southern Ocean. High atmospheric pressure over the midlatitudes pushes air toward the poles. As the winds rush south, they turn eastward with Earth's rotation. In the past few decades, air pressure along the Antarctic coast has often been lower than in previous decades, which strengthens the westerlies and drives them farther south, bringing more warm air to the Antarctic Peninsula. “In years when this happens, there is a 70% chance that the peninsula is warmer and has less sea ice,” says Sharon Stammerjohn, an oceanographer at the University of Colorado, Boulder.

Human activity is partly to blame. Thompson's group, working with climate scientists Susan Solomon of the U.S. National Oceanic and Atmospheric Administration and Nathan Gillett of the University of Victoria in Canada, has found that changes in westerlies during austral summer are caused by the ozone hole over Antarctica, a thinning of the ozone layer in the stratosphere due to decades of consumer use of halogenated chemicals. Ozone absorbs solar radiation; the cooling strengthens surface westerlies and nudges them toward the South Pole. Climate models show that rising concentrations of greenhouse gases amplify that effect on the westerlies. At the same time, lower coastal air pressures suck cold winds from the pole, spreading a deep chill across the Antarctic interior. This helps explain the apparent paradox of the peninsula warming even as average temperatures in most other parts of the continent—except the Amundsen Sea in western Antarctica—have budged little.

Ocean temperatures are another ghost in the machine that could explain what's happening in the Amundsen region, which has experienced accelerating ice loss in recent decades. Sea surface temperatures in the central tropical Pacific, near the International Date Line, have been rising since the early 20th century. The warmer water heats the overlying air, which rises, expands, and meanders south, getting a push from the subtropical jet stream off eastern Australia. About 50° south of the equator, a high-pressure center steers the air mass in the same direction as the westerlies.

“You can think of the westerlies like a tightly wound guitar string,” says David Battisti, a climate scientist at the University of Washington, Seattle. “Pinging on that guitar string by changing tropical convection, you send out waves.” His team's modeling shows that as westerlies intensify, loops of warm air detach and pile up over the Amundsen Sea. Cyclones steer this warm air into the continent's interior. That could explain the correlation between warming in the central tropical Pacific and rising winter temperatures in western Antarctica, Battisti says.

The El Niño–Southern Oscillation (ENSO) is plucking a different section of the guitar string. ENSO is a climate pattern that lurches between two states: El Niño, when tropical eastern Pacific surface waters are unusually warm, and La Niña, when they are exceptionally cool. By analyzing all ENSO events in the past 30 years, Stammerjohn and colleagues found that El Niño is closely linked to warming and light sea ice in the Amundsen Sea, but cooling and heavy sea ice in the Antarctic Peninsula. Modeling shows that El Niño tends to induce a persistent high pressure center west of the peninsula. This draws cold winds from the continental interior to the peninsula and pushes warm winds from the ocean over the Amundsen Sea.

## Nearing the tipping point?

It's not just the air that's growing warmer. The westerlies over the Southern Ocean produce the strongest ocean current on the planet, the Antarctic Circumpolar Current. As much as 4 kilometers deep and 1000 kilometers wide, the current moves 140 million tons of water per second. “Any changes in this powerful current will have a profound impact,” says Michael Meredith, an oceanographer at the British Antarctic Survey in Cambridge, U.K.

As the westerlies are propelled farther south by the ozone hole and atmospheric warming, they tug the Antarctic Circumpolar Current south, pushing ocean heat from warmer lower latitudes toward Antarctica. “The stronger winds also stir up more eddies,” Meredith says. “These swirls of ocean currents, tens of kilometers in diameter, are effective engines to pump warm water towards Antarctica.” The Southern Ocean is already feeling the heat. Since the 1950s, the Antarctic Circumpolar Current's sweet spot—its warmest water at 700 to 1000 meters below the surface—has increased by about 0.2°C, twice as much as the global average warming at that ocean depth. Through research cruises and year-round monitoring at Palmer Station, Stammerjohn and colleagues have charted a steady rise in ocean heat content since the 1990s in waters along the peninsula's continental shelf. They estimate that 80% of the added warmth is from a greater volume of deep, warm water welling up onto the shelf.

This kind of upwelling is unique to the Southern Ocean. As the westerlies drag the currents around Antarctica, surface water flows north with Earth's rotation, and is replaced by warm deep water from below. “At the peninsula, the circumpolar current skirts right along the coast, and stronger winds could easily lift up more deep water onto the shelf,” says Ducklow, an ecologist at the Marine Biological Laboratory in Woods Hole, Massachusetts. On the continent, meanwhile, climate models forecast that cyclones caused by central Pacific warming could also flush more warm deep water onto the continental shelf in the Amundsen Sea. There, a robotic submarine has probed beneath Pine Island Glacier, which is sliding into the ocean at a rate of 4 kilometers a year. The sub's missions are shedding light on how deep water may erode ice sheet stability (see sidebar).

The climate changes down south could have far-reaching ramifications. The preeminent concern is sea levels: how high they will rise as ice sheets succumb to a global warm-up. A less intuitive consequence is how changing conditions in waters off Antarctica will affect the global ocean's cooling and gas exchange. Climate change could influence the amount of cold salty water that sinks to the ocean bottom. Antarctic Bottom Water, as it's called, pools at only a few spots around the continent, where seawater is cooled by overlying air and rendered saltier as ice forms. More than 60% is concentrated in one location: the Weddell Sea, east of the Antarctic Peninsula, where projected changes in ocean currents could accelerate ice sheet disintegration, making the surface water fresher and lighter.

In recent decades, a combination of warmer air, lighter sea ice, and more ice shelf melting has made waters fresher and lighter in parts of the Antarctic coast, says Gregory Johnson, an oceanographer at the University of Washington, Seattle. From ship-based surveys in the Southern Ocean, Johnson and colleagues found that the volume of Antarctic bottom water has decreased by 10% per decade over the past 30 years. Bottom water circulates globally and mixes with warmer waters above, much like refrigerants cooling a fridge. Less bottom water, Johnson says, “could affect heat exchange and climate regulation on a global scale.” Loosening that bridle on ocean temperatures could have catastrophic consequences for the global climate and for sea life, experts say.

In the meantime, there are fears that the Southern Ocean may be losing capacity to store carbon in its depths, which may spur global warming. It accounts for about 40% of the total global ocean uptake of atmospheric carbon dioxide. Stronger upwelling stirs up deep carbon-laden waters. “This can increase carbonate levels in the surface and lead to more outgassing and less uptake,” says Corinne Le Quéré, a biogeochemist at the University of East Anglia in Norwich, U.K. Her team has found that the Southern Ocean has absorbed less carbon in the past 30 years despite rising industrial emissions.

All climate signals point to a grim outlook for the frozen continent. Models predict that the westerlies will grow stronger and drift southward; the central tropical Pacific will continue to warm; areas that are not warming now, such as the Weddell Sea and the Ross Sea, will become hot spots in less than a century if greenhouse emissions are not curbed; and ENSO cycles will grow more intense and flip more frequently. “The implications for Antarctica will be dire,” Shevenell says. Consequences could include widespread ice sheet disintegration, ecosystem deterioration, and disruption of global ocean circulation.

The Antarctic Peninsula is already at the vanguard of climate change—and may be approaching the point of no return. “It might be a good place to develop a capability to predict when the Earth system is close to the tipping point,” Ducklow says. “It's like the canary in a coal mine for what's coming for the rest of the planet.”

• * Jane Qiu is a writer in Beijing. Her trip to the Palmer Station was supported by the Marine Biological Laboratory's Logan Science Journalism Fellowship.

7. Climate Change

# Slip Sliding Away

1. Jane Qiu

Fifty percent more meltwater than 15 years ago is gushing from the cavity beneath Pine Island Glacier and a widening gap between the ice and an underwater ridge crest, probably due to sustained melting.

Pine Island Glacier is part of the weak underbelly of the West Antarctic Ice Sheet. It and other glaciers that flow into the Amundsen Sea are at the foot of the fastest melting ice shelves on the continent. Pine Island Glacier is sliding into the ocean at a rate of 4 kilometers a year and contributes a whopping 4% to the recent global sea level rise of 3 millimeters a year.

To find out what's going on, in 2009 a team led by oceanographer Stanley Jacobs of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York, and glaciologist Adrian Jenkins of the British Antarctic Survey sent a submarine beneath the Pine Island Glacier Ice Shelf: the floating tongue of ice where land-bound glaciers meet the ocean. Compared with data gathered 15 years ago, their findings were alarming. They detected 50% more meltwater gushing from the cavity and a widening gap between the ice and an underwater ridge crest, probably due to sustained melting.

As a result, the current flowing into the ice cavity was 77% stronger in 2009 than it was in 1994. “What goes into the cavity is the warm deep water,” Jacobs says. “You can trace it all the way to the edge of the continental shelf hundreds of kilometers in the north.” The deep water is 3.5°C warmer than the freezing point at 1 kilometer below the ocean surface, where it encounters the ice. “It's very effective at melting ice from the shelf base at that depth,” Jacobs says. As the shelf thins, the ice loses its grip on the sea floor and ice moves more rapidly into the sea.

This increased basal melting has turned out to be a common mechanism of ice loss in coastal Antarctica. In a recent survey, glaciologist Hamish Pritchard of the British Antarctic Survey and his colleagues found that basal melting accounts for thinning at 20 out of 54 ice shelves. “The fastest thinning takes place on the coast of western Antarctica,” Pritchard says. “It's invariably at places where deep warm water can access ice shelves through submarine trenches across the continental shelf.”

Other regions also may not be safe from melting for long, says Hartmut Hellmer, an oceanographer at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany. His group's climate models found that water in the cavity underneath the Filchner-Ronne Ice Shelf in the Weddell Sea would be 2°C warmer by the end of the 21st century under a conservative estimate of carbon emissions and economic growth. Warmer cavity water would increase basal melting 20-fold, resulting in 1.6 trillion tons of ice loss a year. That would freshen waters at the ocean surface and allow deep warm water of the circumpolar current, which now largely stays away from the continental slope, to penetrate into the trough underneath Filchner-Ronne, an ice shelf the size of Spain that's fed by ice streams from both the West and East Antarctic ice sheets. That could conjure a nightmare scenario: “There would be serious implications for the stability of both ice sheets,” Hellmer says.

8. News

# China's Push in Tissue Engineering

1. Mara Hvistendahl

Valued for their innovation potential, biomaterials efforts in China prosper.

NANTONG, CHINA—Mounted to the entrance of the Jiangsu Key Laboratory of Neuroregeneration is a plaque listing two dozen grants—a total of $2.87 million over 18 years, impressive for a lab in the somewhat obscure Nantong University here, a few hours' drive from Shanghai. A sparkling 4000-squaremeter complex outfitted with millions of dollars' worth of equipment, as well as a kitchen, recreation room, and locker and shower facilities, is an even greater testament to the success of the lab's director, Gu Xiaosong. An expert in peripheral nerve regeneration, he's pushed to make neuroregeneration “a distinguishing characteristic of our school.” But in some regards, Gu's lab is not that unusual. It is one of dozens to capitalize on a recent Chinese government push in tissue engineering. Chinese leaders see tissue engineering as a promising area for innovation, says Cui Fuzhai, a bone and brain tissue engineering specialist at Tsinghua University in Beijing: “They feel it is important to the economy—that it has clear applications.” In recent years, China's national grant programs have singled out this field, along with other aspects of biomaterials research, for growth. From 1999 to 2009, according to a recent analysis by the Boston-based technology consulting firm Lux Research, more than$80 million from various government channels went to tissue engineering and stem cell research in the country. While the government tends not to release funding totals for specific research areas, intensive government investment in stem cells didn't pick up until 2011, says Ma Zhun, an analyst with Lux Research in Shanghai. With calls for the Chinese biomedical materials industry to quintuple its share of the global market by 2050, such funding will almost certainly increase in decades to come.

Chinese tissue engineering research dates back to the 1990s, as the field was coming into its own internationally. Chinese scientists established a national Society of Tissue Engineering in 1999. That same year, they held the first national conference on the topic in Shanghai. But resources were limited. Myron Spector, a biomaterials scientist at the VA Boston Healthcare System and Brigham and Women's Hospital in Boston, recalls visiting Cui's lab in the late 1990s. Even at Tsinghua, one of China's top universities, researchers did not have sufficient support. “They didn't get journals, and when they did get them, they were old,” Spector says. He remembers returning to Boston and pricing out what it would cost to send boxes of the leading biomaterials journals to China.

Within a few short years, things changed. In 1997, plastic surgeon Cao Yilin, now one of China's leading tissue engineering researchers, made headlines when he was among a group of researchers in Boston to publish a paper in Plastic and Reconstructive Surgery relating his team's success in growing a human ear—comprised of tissue-engineered cartilage made from a biodegradable polymer seeded with chondrocytes—on a mouse. Cao was based in the United States at the time, working with prominent tissue engineer Joseph Vacanti at Massachusetts General Hospital, but he returned to China soon after. Others say his achievement helped prove the worth of the field to the Chinese government.

In 2001, a government grant program targeting research with commercial potential—the 863 Program—started explicitly funding tissue engineering. From 2002 to 2005, it supported an initial 11 projects in the field, according to Cui. The program currently sponsors 48 projects, says Guo Quanyi, who oversees the 863 Program's tissue engineering grants. The boom in funding has been matched by a steep increase in the number of professors and assistant professors in China working on tissue engineering, Cui says, from roughly 100 in the 1990s to some 300 today.

Cui was among those to benefit from the sudden onset of funding. When Spector revisited the Tsinghua professor's lab a few years later, he was shocked at the improvement in available resources and science being conducted. He listened in awe as Cui's graduate students described innovative biomaterials they were developing to treat defects in the brain resulting from conditions such as stroke. “I had just never heard anything like it,” Spector recalls. “I thought, ‘This is really out there.’”

Returning to the United States, he logged into the publication database PubMed and searched in vain for related research. He realized then that the Chinese scientists had pulled ahead of their Western counterparts in that particular subfield. “What happened in the West over many decades has been compressed into 2 decades” in China, Spector says. “There is definitely work in China that I would say is leading the rest of the world.”

Cui himself is more circumspect about China's prospects. “Our lab conditions are comparable to those in the West. We are very good in some specific areas.” But, he adds: “The overall research level in China is still behind the United States by 20 years.” Others contend, however, that thanks to generous funding and a strong government emphasis on tissue engineering, the gap is closing very quickly.

## Funding boom

Gu's lab exemplifies this progress. About 3% of trauma patients suffer from peripheral nerve damage that paralyzes them or impairs movement. Surgeons can repair such injuries by removing a nerve from elsewhere in the patient, from a leg, for example, and transplanting it at the site of the damaged nerve. But this approach entails two surgeries and the loss of one nerve segment in order to gain another. The alternative, artificial nerve grafts, can typically only bridge gaps of less than 30 millimeters, ruling out their use for more severe injuries.

So when Gu and colleagues began engineering nerve grafts that could bridge longer distances, the work attracted attention. His team was among the first in the world to develop nerve grafts using chitosan, a material usually derived from shrimp or crab shells, and the first to take such grafts to the clinic.

At the time, other teams around the world were working on chitosan-based nerve grafts. But Gu's method allowed scientists to control the speed at which the chitosan conduit biodegrades—a quality “important for the repair of nerve defects with varying length, location, and diameter,” says Yang Xiongli, a neuro scientist at Fudan University in Shanghai.

Gu was also the first to translate this artificial nerve research to the clinic. China's State Food and Drug Administration (SFDA) gave approval for clinical trials in 2010. A trial is now under way at four Chinese hospitals, with 35 grafts completed. Gu expects that it will conclude next year.

He's also combining his chitosan-based grafts with mesenchymal stem cells extracted from bone marrow. In a study forthcoming in Biomaterials, Gu and colleagues describe how this approach bridged a 50-millimeter median nerve gap in rhesus monkeys. In addition, his team is developing other synthetic nerve grafts, including a material derived from a very Chinese substance: silk proteins. “The biocompatibility is better than with chitosan,” Gu says.

Gu has pushed hard to make this progress. It hasn't hurt that for the past 3 years, he has served as Nantong University's Communist Party secretary, a powerful administrative post that ensures him a personal driver, access to education officials, and influence over key planning decisions, and that for the 4 years prior to that, he was the university's president. He is unabashed about steering resources toward nerve regeneration research: “Scientists who come here tend to end up doing neuroregeneration,” he says.

Government largesse helped Gu construct his new lab, which he modeled after the Max Planck Institute of Neurobiology in Martinsried, Germany. And Gu has benefited from generous funding from China's two major grant programs, 863 and 973, as well as from the National Natural Science Foundation of China. The 973 Program focuses on basic research, and from 2009 to 2011, its funding for nanotechnology, a category that encompasses advanced materials, advanced diagnostics, electronics, and tissue engineering, totaled more than $82 million, according to Lux Research. From 2006 to 2011, the 863 Program poured$77 million into tissue engineering and stem cell research.

The sums given by the U.S. National Institutes of Health and the Armed Forces Institute of Regenerative Medicine for tissue engineering research in the United States often exceed those awarded in China, says Liu Wei of the Shanghai Key Laboratory of Tissue Engineering, who cautions that it is difficult to compare funding in the two countries. But Chinese scientists often get matching funds from the local and provincial governments to sweeten the deal. The influx of cash means that China is positioned to “become one of the major players in this field,” says James Yoo, a regenerative medicine specialist at the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina.

## Push toward translation

Gu's team is now trying to figure out why peripheral nerves can regenerate in people while other human nerves, such as the spinal cord, can't—a question that still perplexes researchers around the world. But such basic research questions may soon fall by the wayside in China as more money becomes available for clinical research. “Five or 6 years ago it was enough for us simply to publish,” Gu says. “Now the government wants us to translate our research into clinical applications.”

China's \$56 billion biomedical materials industry is largely driven by foreign technology; domestic companies accounted for a mere 3% of global market share in 2011. Government leaders have decided that's too little, Ma says: “The current target is to commercialize tissue engineering technologies and bridge the gap between academia and industry.” Eyeing a lucrative market with potential for growth, the Chinese government recently set a goal of increasing China's share of the global biomedical materials market to 10% to 15% by 2050.

As government interest in tissue engineering research shifts toward clinical translation, the funding split is changing as well. Tissue engineering “is a field with a huge capacity for innovation, and it promises solutions to a lot of problems that modern medicine hasn't been able to solve,” Guo says. He says the current batch of government-funded projects span cartilage, nerve, bone, heart, ligament, eye, and skin research.

Already, Gu has been particularly effective at applying his research, say scientists familiar with his work. “He understands the clinical needs,” says Yoo, whose institute signed an agreement earlier this year with the Jiangsu Key Laboratory of Neuroregeneration to establish a joint center.

And Gu is hardly alone. In 2007, SFDA approved China's first tissue-engineered product: ActivSkin. Developed by researchers at the Fourth Military Medical University in Xi'an, it made China the second country in the world, after the United States, to possess artificial skin technology. Products approved since then include a bone repair scaffold developed by Cui that cleared SFDA in 2010. The material has been used by 30,000 patients in China and its application is being pursued elsewhere in the world, he says.

Translational research promises to become one of China's strengths in tissue engineering, says Cao, the plastic surgeon whose work on cartilage engineering originally helped spark interest in the field. Now director of the Shanghai Key Laboratory of Tissue Engineering, he and Liu are working on clinical applications of engineered cartilage, bone, tendon, skin, and blood vessel grafts.

But the regulatory hurdles can still be substantial in China. Individual components of the grafting process require safety approvals before any clinical trials can start. Thus, Cao and Liu have yet to receive SFDA approval to start clinical trials on any of their products. Moreover, SFDA staff members are reluctant to green-light trials for tissue-engineered devices that haven't first been approved outside of China, Ma says. As a result, some Chinese scientists now apply for trials in Australia or the United States before seeking permission to work in patients domestically.

But the approval process for clinical trials can drag on for years. For many Chinese scientists, a lack of experience navigating their country's regulatory agencies is an obstacle, says Dai Kerong, director of Shanghai Jiao Tong University's Bone and Joint Research Center: “From bench to bedside—everybody knows it's important, but most physicians don't know how to do it.”

Bureaucratic intransigence may be only temporary. SFDA is investing money in developing more coherent regulatory standards, Ma says. And Dai is spearheading a series of seminars for tissue engineering scientists on how to navigate the trial application process and steer their research toward the clinic. “The important thing is China now has the funding mechanisms, both public and private, and the SFDA is now acting judiciously,” Spector says. But it could take time before more scientists achieve the success that Gu has had in moving their research into the clinic. “The central government has put a lot of money into this field,” says Dai, who mentored some of China's younger tissue engineering researchers and remembers when things were very different. “The problem has become how to use it—so we don't waste it.”