Rare Gorillas at Risk as Rebels Seize Congo Park

Heavy fighting continues to rage in the Democratic Republic of the Congo's (DRC) troubled Virunga National Park, one of the last remaining homes for rare mountain gorillas.

On Sunday rebels loyal to renegade general Laurent Nkunda—who have been clashing with DRC military forces in the area since September 3—took control of the park's gorilla sector.

The fighting has sparked further fears for the safety of the critically endangered mountain gorillas, which have been left largely unprotected for more than a month, ever since the clashes forced rangers to evacuate the park.

Today the fighting between rebels and the Congolese army heated up near Bukima, the park's main gorilla monitoring station.

Rangers could also hear the exchange of heavy gunfire near park headquarters at Rumangabo, according to Norbert Mushenzi, director of Virunga's gorilla sector for the Congolese Institute for the Conservation of Nature (ICCN).

"Rangers and local inhabitants are fleeing from all around the park, and the mountain gorillas are totally unprotected," Mushenzi said.

"This whole situation is precarious and frustrating."

Rebels vs. Rangers

About 700 wild mountain gorillas remain in the world, roughly 380 of which live in the Virunga Volcanoes Conservation Area shared by the DRC, Rwanda, and Uganda.

Of these, about 120 are found in the DRC.

But rangers there have been able to track only one family of gorillas since the fighting started five weeks ago, and they have yet to account for 54 of the region's 72 habituated gorillas.

Until last week the situation had appeared to be calming, and rangers were hoping to re-enter the sector to track the gorillas.

But last Friday rangers who had been monitoring gorillas from a post inside the park had to flee when the rebels reportedly tried to force them to become combatants.

Rebel leader Nkunda, who is an ethnic Tutsi, maintains that the government is collaborating with ethnic Hutu rebels hiding in the DRC who are accused of involvement in the 1994 genocide against Tutsis in neighboring Rwanda.

On September 3 the rebels surrounded two ranger stations inside Virunga. The men seized rifles and communications equipment and forced park workers and their families to evacuate.

Since then the rebels have consolidated their grip on the park, conservationists say.

"The army seems to be weakening vis-à-vis the rebels—and this does not bode well for the gorilla sector at all," said Samantha Newport, a spokesperson for WildlifeDirect, an environmental group that supports the DRC rangers.

Fighting for Control

Conservationists said control of the park is important for the rebels.

"The gorilla sector is a key strategic point in this conflict. The rebels want to control it and have access to neighboring countries to replenish their materials and equipment," said Emmanuel de Merode, head of WildlifeDirect.

"The mountain gorillas are stuck right in the middle."

At least ten gorillas have been killed in Virunga this year, and some of the deaths have been blamed on the rebels.

The worst attack occurred on July 22 when five gorillas, including a silverback, were shot dead execution-style.

That attack was linked to the burgeoning charcoal trade in the park. (Read "Congo Gorilla Killings Fueled by Illegal Charcoal Trade" [August 16, 2007].)

In September a dead infant female was found in the hands of alleged traffickers who are now facing judicial procedures in the city of Goma, just south of Virunga.

Newport said there is a strong possibility that the rebels may soon cut off the road between Goma and park headquarters at Rumangabo, thereby totally isolating the 34 rangers there.

The rangers have removed all valuable tracking equipment from Rumangabo in case the clashes reach the area.

One ranger also died this week in a car accident.

The man was coming back with his colleagues from an anti-charcoal burning patrol when he fell out of the pick-up truck they were riding in. He was taken to a hospital, but later died from brain damage.

Early Venus Had Oceans, May Have Been Habitable

Venus, not Mars, may have been the most likely planet in the solar system to have also developed life, scientists say.

The cloud-shrouded planet most likely started with oceans much like Earth's, which evaporated as Venus heated up, according to new research.

The oceans didn't disappear overnight, said David Grinspoon of the Denver Museum of Nature and Science.

Speaking yesterday at a meeting of planetary scientists in Orlando, Florida, Grinspoon said that preliminary results of new computer models indicate Venus may have retained its oceans for a billion years after it formed, possibly longer.

Prior models had indicated that rising Venusian temperatures had turned the oceans to steam within the planet's first 600 million years.

The extra 400 million years are even more significant than they sound, Grinspoon added, because early Venus was constantly bombarded by asteroids, reducing the likelihood of life.

The new finding suggests that the oceans existed for much longer after the asteroid bombardment tapered off.

"There may have been a sizeable interval when [Venus] was habitable," he said.

Today, however, Venus is about 100,000 times drier than Earth and is 860º F (460º C) at its surface, Grinspoon said.

New Discovery From Venus

Future studies might further refine our understanding how long the planet was habitable.

If samples can be collected from the surface, for example, scientists might find rocks that formed when the planet was wet, Grinspoon said.

Determining how much water remains locked in these rocks may allow scientists to figure out how long ago the planet dried out.

Similarly, studies of Venusian gases could help scientists better estimate the rate at which water was lost into space.

Already such research is playing a role in our understanding of Venusian heating.

At the Orlando meeting, French researcher Jean-Loup Bertaux reported that the Venus Express spacecraft, now orbiting the planet, has discovered a rare form of carbon dioxide never before detected on Venus.

Instead of containing the most common form of oxygen, which has eight protons and eight neutrons, this one has one atom of oxygen with eight protons and ten neutrons.

That causes it to absorb more infrared light than normal carbon dioxide, increasing its strength as a greenhouse gas.

(See a photo of "airglow" created by oxygen in the Venusian atmosphere.)

The upsurge of interest in Venus comes hard on the heels of a recent finding that early Mars might have been colder and drier—and therefore less habitable—than previously believed.

Thunderstorm Gamma Rays Linked to Lightning

The formation of gamma rays—the most energetic form of light—in thunderclouds may be linked to lightning production, a new study shows.

Gamma rays are typically produced by cosmic cataclysms like supernovae, but terrestrial thunderstorms can also energize particles enough to create the powerful rays.

Scientists first spotted gamma rays in thunderstorms in the early 1990s. The Compton Gamma Ray Observatory unexpectedly detected radiation originating from the ground while peering at distant supernovae.

"The fact that they are [even] created in something as garden variety as thunderstorms is a surprise," said Steven Cummer, an electrical engineer and lightning researcher at Duke University in Durham, North Carolina.

Lightning Mystery

How thunderclouds produce the rays has not been explained. Neither has the nature of their apparent link to lightning formation, about which many long-standing mysteries remain.

But a new study led by Teruaki Enoto of the University of Tokyo and Harufumi Tsuchiya of RIKEN, Japan's Institute of Physical and Chemical Research, has provided the best look yet at the phenomena.

The team trained an array of gamma ray detectors on two powerful low-pressure air masses that collided over the Sea of Japan on January 6, 2007.

The researchers found that gamma rays were produced some 70 seconds before a lightning strike. They also determined that gamma bursts, which had been previously measured to last less than a second, could occur for almost a minute.

The findings suggest that whatever triggers gamma rays might also be involved in creating lighting—and that their origin might be tied to powerful particles known as cosmic rays that continually rain down from space.

The work will appear in an upcoming issue of the journal Physical Review Letters.

Cosmic Ray Trigger

In the new study, the researchers provide additional evidence that cosmic rays trigger gamma ray generation by releasing a "seed electron" from an atom of air.

This begins "runaway breakdown"—a theoretical process in which the liberated electron ionizes nearby air molecules. These molecules become accelerated in the very high electric fields inside a thundercloud, which can reach up to ten million volts in strength.

A group of fast electrons is then formed, which can emit gamma rays as they are gradually slowed down by contact with surrounding air molecules.

"Everybody agrees that in some way this basic process of runaway breakdown is involved, but whether it has to be triggered by a cosmic ray [is uncertain]," said Cummer, who did not participate in the new Japanese research.

"It's appealing on some levels, but others have suggested ways that don't necessarily [require] a cosmic ray coming through."

Cosmic rays are constantly raining down onto Earth, so it is difficult to isolate their impact on any single event, he pointed out.

Lightning Link

Still, studying thundercloud gamma rays could eventually unlock some secrets of Earth's weather, the Japanese researchers say.

"One significance of our result is the prospect that we can use these gamma rays as a good probe to understand how the strong electric field develops in thunderclouds and how lightning discharges occur," study lead author Enoto said.

The electric fields in thunderstorms appear to be too weak to form lightning, so scientists have been puzzled by how the bolts form. Cosmic rays have also been suggested as a trigger for the flashes.

The researchers are now looking into the exact connection—if any—between runaway breakdown and lightning, especially if such a link applies only to certain kinds of lightning or in certain areas of storms.

Thundercloud gamma rays could also shed light on more exotic cosmic processes like solar flares, pulsars, and jets from black holes, Enoto added.

"Our result shows that thunderclouds may be a natural particle accelerator," he said. "Thunderclouds could provide a nearby hidden prototype for other energetic cosmic accelerators."

No Radiation Danger

Powerful gamma rays can be dangerous in some cases, since the radiation can reach energies a hundred to a thousand times higher than x-rays used in medical devices, Enoto said.

But storm clouds are unlikely to produce enough radiation to cause any worry.

"The total number of detected gamma rays is so small that the overall radiation dose is meager—perhaps seven orders of magnitude less than that of a single medical radiography shot," he explained.

"So this event, we presume, has little impact on Earth or human bodies."

Steamier Earth Likely, Due to Global Warming

Human activity has long made the bedroom a hot and steamy place. Now, less sexy activities like burning coal and oil—major contributors to global warming—are making the whole planet steamier, a new study says.

Scientists expect the rising humidity to cause heavier rains, stronger hurricanes, and increased human heat stress.

Climate scientists have long predicted that a warmer world will allow more water to evaporate, thus making the planet more humid.

Indeed, several studies have shown trends of increasing surface humidity around the planet, but until now scientists were uncertain what was driving the trend.

The new study combined a fresh data set of surface humidity with climate models, "and actually attribute[s] those trends to human influence," said study co-author Nathan Gillett, a climate scientist at the University of East Anglia in Norwich, England.

He and his colleagues report the findings in tomorrow's issue of the journal Nature.

Stormy, Steamy Future

Climate models predict that increased water vapor in the atmosphere will lead to heavier rains and raise the maximum potential intensity for hurricanes, Gillett noted.

"In heat waves, if the humidity is higher, then that results in larger heat stress on humans," he said.

And increased water vapor will accelerate the warming, said Benjamin Santer, a climate modeler at the Department of Energy's Lawrence Livermore National Laboratory in California who was not involved in the study.

"Our best understanding is as we increase greenhouse gases and warm the atmosphere, we increase the atmosphere's capacity to hold moisture. And water vapor is in itself a potent greenhouse gas.

"Therefore you accelerate the warming," he said.

Steve Sherwood is a climate scientist at Yale University in New Haven, Connecticut, who was not involved in the study. He said the findings are uncontroversial, but the new data set is a boon.

"People haven't really been talking enough about what higher humidity is going to mean in the future," he said, "and part of the reason they haven't been talking about it is that we haven't had very good data."

"They've put out a data set that people can actually use to look at long-term changes," he added.

Global Warming Evidence

Santer of the U.S. Department of Energy led research published recently in the journal Proceedings of the National Academy of Sciences that linked human activity to an increase in atmospheric water vapor. (Gillett was a co-author of that paper.)

Gillett, co-author on the new Nature study, also contributed to a July paper in the journal Nature that linked human activity to changes in rainfall patterns over the past century.

This body of work should silence criticism that the only evidence of global warming comes from surface and ocean temperature records, Santer said. Human influence is prevalent throughout the climate system, he added.

The combined studies should also help scientists more accurately predict Earth's response to increasing levels of greenhouse gases, Gillett said.

For example, he said the models used for the July Nature study underestimated the change in rainfall due to global warming, but that the models do a "reasonably good" job of capturing the humidity changes.

"These results will help to pin down which parts of the hydrological cycle the models can simulate well and which not so well ... and help improve the models," he said.

Nanotech Find Earns Two Europeans Nobel in Physics

Frenchmen Albert Fert and German Peter Grünberg have won the 2007 Nobel Prize in Physics for their discovery of the phenomenon that makes modern-day hard-drive technology possible.

The Royal Swedish Academy of Sciences today announced that the two scientists will equally split the prize "for the discovery of giant magnetoresistance [GMR]," which amplifies small magnetic changes into large electrical signals.

The discovery has made possible the massive hard drives used in modern computers, cell phones, and music players, which store data magnetically.

"The practical benefits of this physics could not be greater," said Phillip Schewe, a spokesperson for the American Institute of Physics. "GMR is at the heart of the multi-billion-dollar hard-drive industry."

"This discovery played a key role in the phenomenal increase in storage capacity and reduction in size of magnetic recording systems that are the essential components of modern consumer products such as iPods and computers," added S.A. Solin, a professor of physics at Washington University in St. Louis, Missouri.

In the prize announcement, the Royal Swedish Academy also said that "GMR can also be considered one of the first real applications of the promising field of nanotechnology."

"Weird" Physics

Hard drives store data by magnetizing extremely small sections of material, similar to how VCRs and tape recorders work. But as more data is stored in the same amount of space, the magnetic signals get weaker.

This fact limited hard drive capacities until Fert, of the Université Paris-Sud in Orsay, France, and Grünberg, of Forschungszentrum Jülich in Germany, independently came across giant magnetoresistance in 1988.

The effect is a far better method for reading stored data, and the first GMR-based hard disks were created less than a decade later.

The scientists uncovered the phenomenon while studying the exact properties of extremely thin stacks of metal.

At just a few atoms thick, the layers were expected to experience unusual quantum effects. Fert and Grünberg found this included magnifying very weak magnetic changes into major differences in electrical conductivity.

"It's just an esoteric, weird type of physics, but a force that can be exploited to make valuable products," Schewe said.

"This is a wonderful example of how an accidental scientific discovery can have an extraordinary impact in technology—a marked increase in magnetic storage for information processing," added David Awschalom, a professor of physics and electrical engineering at the University of California, Santa Barbara.

Future storage devices might also be inspired by giant magnetoresistance, which relies on a property of electrons called spin.

Scientists are now exploring how to use spin to create new kinds of circuits and electronics, a field known as "spintronics."

"The increasing interest in semiconductor spintronics—our field—has partly also been inspired by the success of the GMR and its consequences," said physicist Manfred Ramsteiner of Paul Drude Institute in Berlin, Germany.

Fert and Grünberg will equally split the prize of 10 million Swedish kronor (about 1.5 million U.S. dollars).

Nobel Pursuits

Last year U.S. scientists John C. Mather and George F. Smoot won the Nobel Prize in Physics for research that helped solidify the big bang theory of the origin of the universe.

And yesterday three scientists— Mario R. Capecchi and Oliver Smithies of the United States and Sir Martin J. Evans of Britain—won the 2007 Nobel Prize in Physiology or Medicine for work on manipulating mouse genes to improve studies of genetic diseases.

The Nobel prizes have been awarded since 1901 based on the will of chemist and engineer Alfred Nobel, who invented dynamite.

The 2007 prizes in chemistry, literature, peace, and economics will be announced over the next two weeks.

The awards will be officially presented on December 10, the anniversary of Nobel's death.

"Missing" Moons, "Dirty" Ice Among Jupiter Flyby Finds

"Missing" moonlets, a huge volcanic eruption, and new maps of possible ocean ice are among the results of a recent flyby of Jupiter's moons.

The observations were made as NASA's New Horizons spacecraft whipped around the gas giant this past spring on its way to rendezvous with the dwarf planet Pluto in 2015.

Using Jupiter's gravity like a slingshot allowed New Horizons to shave years off its travel time to distant, icy Pluto.

The approach was also the first time a probe had been that close to Jupiter since the Galileo mission ended in September 2003.

Several teams of scientists used the opportunity to capture detailed images that allowed them to study different aspects of Jupiter.

Their findings appear in this week's issue of the journal Science.

No Tiny Moons

Perhaps the most surprising find for astronomers was an absence of tiny moonlets within the planet's rings.

Prior missions had revealed four small moons orbiting inside the orbit of the large moon Io.

The smallest of these are Adrastea, at 12 miles (20 kilometers) in diameter, and Metis, at 25 miles (40 kilometers) in diameter.

Earlier instruments weren't sensitive enough to spot moons much smaller than these. But scientists presumed that moonlets existed, because where there are big objects, there are usually lots of smaller ones.

"That's sort of how these things work," said Mark Showalter, a planetary scientist at the SETI Institute and lead author of a study on the "missing" moonlets.

Looking for moonlets is important, Showalter said, because they are thought to be the source of the dust that forms Jupiter's faint rings.

Such dust can be created when meteorites hit small moons within the rings, forming puffs of smokelike particles.

But despite the probe's ability to spot objects as small as 0.6 mile (a kilometer) in diameter, New Horizons found no new moons.

"It was really a surprise," Showalter said.

The most likely explanation, he continued, is that meteorite bombardment has battered such small bodies to the point that they are too small for New Horizons to detect.

But the new pictures did produce an unexpected find: clumps of debris within the planet's main ring.

While clumps of material aren't unusual, Jupiter's clumps were found in clusters that should have been rapidly dispersed by orbital forces.

"We haven't seen anything like this in any other planetary rings," Showalter said.

Lava and Frost

Other scientists examined three of Jupiter's larger moons—Io, Europa, and Ganymede.

Io is the most volcanically active body in the solar system.

During the flyby, a team led by John Spencer of the Southwest Research Institute in Boulder, Colorado, took a close look at the moon's giant Tvashtar volcano.

The massive mound happened to be undergoing a major eruption at the time of the flyby—as seen in an image released by NASA in May.

The volcanic plume was more than 215 miles (350 kilometers) high and 680 miles (1,100 kilometers) wide.

In their new study of the volcano images, Spencer and colleagues suggest that the plume's visible particles were not spewed from inside the moon but are instead gases that condensed in the frigid vacuum of space.

The team also notes that the magma inside Tvashtar and other Ionian volcanoes appear to be hot enough to be made of an Earthlike basaltic rock.

Another team, led by Kurt Retherford of the Southwest Research Institute, tried to determine what fraction of Io's atmosphere comes from volcanic emissions.

Io, Retherford said, has a very tenuous atmosphere made up of sulfur dioxide.

The scientists predicted that some of this gas comes from volcanism but that the rest comes from the evaporation of sulfur dioxide frost beneath the daytime sun.

The New Horizons flyby allowed the team to test this theory by studying Io's atmosphere when the moon passed out of the sun into Jupiter's shadow.

When there was no longer any solar heating, they found, 97 percent of the atmosphere quickly turned back into frost.

Ice Maps

When examining Europa and Ganymede, New Horizons scientists were primarily interested in mapping the distribution of "dirty" versus "clean" ice on the moons' surfaces.

The ultimate goal is to resolve a longstanding debate over the source of the material that contaminates the ice, particularly on Europa.

Europa is widely believed to have an ocean beneath its permanently frozen surface.

Scientists hope that the "dirty" ice is salt water that once welled up from below, which would provide proof of the undersurface ocean. But it could also be ice contaminated with sulfur compounds from nearby Io.

Studying the ice might offer clues to whether the underlying ocean is suitable for life, said William Grundy, a planetary scientist at the Lowell Observatory in Flagstaff, Arizona, who led the study.

The New Horizons instruments are sophisticated enough to tell what materials might be in the dirty ice, Grundy added, but at the time of the flyby the instruments hadn't been calibrated.

Once calibration is complete, he hopes to reanalyze the data to get a better answer.

Sex-Changing Chemicals Found in Potomac River

Ever since the discovery of gender-bending fish in the Potomac River, scientists have wondered what could be changing the sex of large numbers of fish in the waterway outside Washington, D.C.

They may not have to wonder much longer.

A recent U.S. government study has found large quantities of chemicals in the river and its tributaries—pollutants that are known to cause sex change in animals.

These chemicals, from both residential and industrial sources, may be linked to the unnatural fish, says the U.S. Geological Survey (USGS) report, which was released late last month.

Males With Eggs

The discovery of the abnormal fish "was largely accidental," said Douglas Chambers, a USGS scientist who led the study.

"In 2002 we were looking at stream-water chemistry to understand the large fish die-offs at these sites. It was then that we found smallmouth bass with intersex, a condition where male fish develop premature egg cells."

During a 2003 survey of the Potomac River and the Cacapon River of West Virginia, Chambers and his colleagues found large numbers of intersex fish.

The researchers also found chemicals from pesticides and flame retardants as well as fragrances commonly found in products such as soaps, antiperspirants, and deodorants.

"We analyzed blood plasma of 30 smallmouth bass from six sites," Chambers said. "All the fish contained at least one of the polluting chemicals, including fish that were not intersex."

However, Chambers said, the study has so far not turned up a single case of "imposex"—the condition in which female fish have malformed ovaries or produce sperm.

Once absorbed by the body, these chemicals—known as endocrine disruptors—interfere with normal bodily functions either by mimicking or blocking the production of hormones.

Experts say endocrine disruptors are found in pesticides, pharmaceuticals, fumigants, and fungicides. Municipal and domestic sewage and wastewater from farms and industries might be routing these chemicals into the water supply.

The presence of such chemicals is not unique to the Potomac. The pollutants have previously been documented in bodies of water in other parts of the United States as well as in Europe.

Scientists have also found reproductive problems in fish and birds in habitats along the U.S. Great Lakes. Similarly, declining alligator populations in Florida's Lake Apopka have been linked to synthetic chemicals that hinder reproduction.

Pollution Cocktail

Chambers says the USGS is analyzing data from last year and is planning to release a more detailed report later this year. The next report will try to make a definitive link between these chemicals and their effects on the environment.

"Currently many of these compounds have not been well researched for their environmental characteristics, how they are taken up by living organisms, and how they can be removed from streams," he added.

Dana Kolpin is a USGS research hydrologist and director of the agency's Emerging Contaminants Project. He reviewed Chambers' study but is not connected with it.

"This is the first step to understanding a very complex issue," Kolpin said.

"We need to understand the cocktail of compounds that are in the environment and whether there are certain bad actors that are causing feminization of males—and what it means for humans [who use this water]."

"It is critical to know where the sources are, how the compounds are being transported, and which ones are being degraded. What happens to them [after they enter the river] is the million-dollar question."

Coal Mining Causing Earthquakes, Study Says

The most damaging earthquake in Australia's history was caused by humans, new research says.

The magnitude-5.6 quake that struck Newcastle in New South Wales on December 28, 1989, killed 13 people, injured 160, and caused 3.5 billion U.S. dollars worth of damage.

That quake was triggered by changes in tectonic forces caused by 200 years of underground coal mining, according to a study by Christian D. Klose of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York.

The quake wasn't enormous, but Australia isn't generally considered to be seismically active and the city's buildings weren't designed to withstand a temblor of that magnitude, Klose said.

All told, he added, the monetary damage done by the earthquake exceeded the total value of the coal extracted in the area.

Klose presented his findings at a meeting of the American Geophysical Union in San Francisco, California, last month.

Heavy Burden

The removal of millions of tons of coal from the area caused much of the stress that triggered the Newcastle quake, Klose said.

But even more significant was groundwater pumping needed to keep the mines from flooding.

"For each ton of coal produced, 4.3 times more water was extracted," Klose said.

Other mining operations, he added, sometimes require as much as 150 tons of water to be removed for each ton of coal produced.

"So this is on the low end," he said.

Human-Caused Quakes

Coal mining isn't the only human activity that can trigger earthquakes.

Klose has identified more than 200 human-caused temblors, mostly in the past 60 years. "They were rare before World War II," he said.

Most were caused by mining, he said, but nearly a third came from reservoir construction.

Oil and gas production can also trigger earthquakes, he added.

Three of the biggest human-caused earthquakes of all time, he pointed out, occurred in Uzbekistan's Gazli natural gas field between 1976 and 1984

Each of the three had a magnitude greater than 6.8, and the largest had a magnitude of 7.3.

Human-triggered earthquakes are particularly dangerous, Klose said, if they occur in seismically inactive areas.

That's partly because people aren't prepared for them. But also, he said, "regions that are naturally inactive are very trigger-sensitive, because stress has built up over long periods of time."

Expensive Implications

Klose's presentation drew considerable attention from the assembled geophysicists, who wondered if there were ways to reduce the risk by altering mining practices.

"One way would be to find a way that doesn't reduce the water in the mine," Klose said.

But as far as he knows, mining engineers aren't examining this, because they are currently unaware of the earthquake risk.

The danger is also relevant to proposals to sequester carbon dioxide by injecting it into geologic formations deep underground where the gas cannot escape and contribute to global warming.

"That alters stress in the crust [too]," Klose said, adding that the risk of earthquakes should be taken into account in planning the locations of such facilities.

Basically, he said, "don't put the injection fields close to large cities."

The research could also have an impact on earthquake-insurance premiums, André Unger of the University of Waterloo, in Ontario, told National Geographic News by email.

The precise method by which premiums are calculated is a deeply guarded trade secret, but they appear to be based on a region's historical earthquake risk—"a purely statistical methodology," he said.

The new finding indicates that other factors are now at work, he said.

Furthermore, Unger noted that underground carbon sequestration might be a mixed blessing from insurance companies' points of view.

A carbon-sequestration plan could reduce the risk of some types of damage (such as from hurricanes, which some scientists say are being strengthened by global warming), while increasing the risk of others, like earthquakes.

Corals May Have Defense Against Global Warming

Ancient corals may have been more adaptable to changing ocean chemistry than previously thought, a new study shows.

The findings may offer hope that if the diversity of modern corals is preserved, they may be able to adapt as global warming causes seas to become more acidic.

These fossil corals in diverse reef communities adjusted to an acidic environment by altering the way they built their chalky skeletons.

Modern hard corals—known as scleractinians—form reefs of thousands of tiny skeletons made from a calcium carbonate called aragonite.

Aragonite is susceptible to the corrosive effects of acidic oceans, which today has become a byproduct of a build-up of carbon dioxide in the atmosphere.

"We now have many different arguments to prove that these corals were actually made originally out of calcite—and not just aragonite that was transformed after the coral died and become fossilized," said study co-author Jaroslaw Stolarski, a paleontologist from the Institute of Paleobiology at the Polish Academy of Sciences.

Curious Coral

The calcite skeletons were identified using several tests. Scientists inspected the microscopic structure of the skeleton and detected a high ratio of magnesium to calcium—a telltale fingerprint of calcite, not aragonite.

The fossil corals look like two-inch-long (five-centimeter-long) sea anemones nestled in porcelain egg cups. They belonged to the genus Coelosmilia, which existed during the Cretaceous period about 70 million years ago.

The Cretaceous oceans had a chemistry different than today, with much less of the metal ion magnesium and higher acidity.

"In the same environment there were coral neighbors, some with aragonitic skeletons, some with calcitic skeletons," Stolarski said.

"There was great biological variability among the corals, and some of them adjusted perfectly to the prevailing geochemical situation," he said.

Rachel Wood, a geologist from the University of Edinburgh, who was not involved in the study, said, "It begs the question: If having a calcite skeleton was so much better for life in such a corrosive sea, why aren't there more of them?"

The research will appear tomorrow in the journal Science.

Diversity Benefits

"This study has opened the door to the possibility that coral skeletons can potentially change back and forth from aragonite to calcite," said Stephen Cairns, research zoologist at the Smithsonian Institution's National Museum of Natural History in Washington, D.C.

"It suggests that animals and plants in general are quite adaptable creatures, and even though Earth changes—sometimes dramatically, like [in the case of] a comet hitting and wiping out 90 percent of animal life—it is so resilient that a vestige still gets through."

Co-author Stolarski said that diversity may be the key to adaptability, even in today's corals, which are under threat from warming seas.

"We should be extremely careful about coral reefs today, because they can only adapt to these changing environments if they maintain their diversity."

"If we completely eliminate some families or groups of corals, we may lose the very corals that would be able to adjust to changing environments in the future."

Cycad Plants "Woo" Insects With Heat, Odor

A primitive type of cycad plant from Australia relies on a surprisingly sophisticated system of meting out food to ensure successful pollination.

These plants take an active role in their reproduction by selectively attracting and repelling small insects known as thrips, a new study shows.

Scientists had long thought that cycads were passively wind-pollinated.

But in a push-pull system, male cones of this "living fossil" species heat up and emit strong odors to send pollen-bearing insects fleeing.

Female cones then emit a more attractive perfume to lure the bugs back in.

Pollination accomplished.

"I think the work demonstrates that plants aren't just sitting there looking pretty or just smelling good to attract their pollinators and that there's a lot more dynamics involved," said study co-author Irene Terry, a biologist at the University of Utah.

The mechanics of such primeval systems could provide insight into how pollination occurs in natural environments such as forests, something that Terry says there is still much to learn about.

The study appears this week in the journal Science and was funded in part by the National Geographic Society, which owns National Geographic News.

Nagging Mystery

Cycads are one ancient lineage of seed-producing plants called gymnosperms, which also include firs, spruce, pines, sequoias, and redwoods.

Found in tropical and subtropical areas, all species of cycads have separate male and female parts, often producing cones that look similar to a pinecone.

Tiny cracks between the tightly woven scales of the cones allow thrips to gain access to pollen in male cones and to structures containing eggs in female cones.

Both larval and adult thrips prefer the male cones, because the insects feed only on pollen.

But using some chemical tricks, the plants looked at in the new study ensure that thrips carry the male reproductive cells into the female cones.

"Twenty-five years ago when I began studying cycad pollination, it was still widely believed that cycads, like other gymnosperms, were wind-pollinated," said William Tang, an entomologist with the U.S. Department of Agriculture.

"Although I was involved in some of the early studies on cycad insect behavior, cone physiology, and odor analyses that supported the notion of insect pollination in this group, the precise details of this mutualism remained a nagging mystery," added Tang, who was not involved with the new study.

"This paper presents an elegant use of biochemistry, physiology, and field ecology to reveal the fine details of how this plant and its insect pollinator interact," he said.

"Through the use of heat and volatile chemicals, the plant choreographs a dance with its pollinators."

Stinky Males

Cycads have variable pollination periods, with reproduction occurring once a year to once every several years and lasting up to four weeks.

During that time, male cones use stockpiles of sugars and fats to heat themselves up, sometimes reaching 100 degrees Fahrenheit (38 degrees Celsius).

The cones also spew out huge doses of an odorous chemical called beta-myrcene.

"The odors get so strong that I don't want to be around them," study co-author Terry said.

"Some plants produce a stinky odor like a dead animal or poop, but this odor is just very harsh, hard to describe in terms of something similar."

Beta-myrcene attracts thrips at low concentrations, but in the amounts emitted by male cones, it becomes highly repellant, explained Robert A. Raguso, a chemical ecologist from Cornell University who was not involved in the study.

"This is a rather emphatic invitation for the thrips [to] leave home, and they do so bearing pollen," he said.

The plants do this "without dramatically changing their structural or visual characteristics, or even the chemistry of their scent," he added.

Tricky Females

Female cones emit much less beta-myrcene, so fleeing thrips searching for more pollen are drawn there.

When the thrips get inside the female cone, the ovule—containing the female reproductive cells—releases a little droplet, similar to a nectar droplet.

This draws the insects farther in. If they are carrying pollen, pollination is inevitable.

"The [study] highlights an elegant physiological mechanism by which cycads manipulate the behavior of thrips, transforming them from neutral or perhaps detrimental pollen predators to helpful pollinators," Raguso said.