Maryland Scientists Build Bacterial Chromosome

By Rick Weiss
Washington Post Staff Writer
Friday, January 25, 2008; Page A04

Scientists in Maryland yesterday said they had built from scratch an entire microbial chromosome, a loop of synthetic DNA carrying all the instructions that a simple cell needs to live and reproduce.

The feat marks the first time that anyone has made such a large strand of hereditary material from off-the-shelf chemical ingredients. Previous efforts had yielded DNA strands less than one-twentieth the size, and those pieces lacked many of the key biological programs that tell a cell how to stay alive.

On the basis of earlier experiments, the researchers believe the new, full-length loop would spontaneously "boot up" inside a cell, just as a downloaded operating system can awaken a computer -- a potentially historic event that would amount to the creation of the first truly artificial life form.

Team members emphasized that they have not done that yet but expressed confidence that they would do so before the end of the year.

"There are barriers . . . but we are confident that they can be overcome," said J. Craig Venter, who led the effort with Daniel G. Gibson and Hamilton O. Smith at the J. Craig Venter Institute in Rockville. The work appears in yesterday's online edition of the journal Science.

Venter said the goal is to design novel microbes whose handcrafted genomes endow them with the ability produce useful chemicals, including renewable synthetic fuels that could substitute for oil.

Critics, however, countered that without better oversight of the fledgling field, synthetic biology is more likely to lead to the creation of potent biological weapons and runaway microbes that could wreak environmental havoc.

"Venter is claiming bragging rights to the world's longest length of synthetic DNA, but size isn't everything. The important question is not 'How long?' but 'How wise?' " said Jim Thomas of the ETC Group, a Montreal-based group that has called for a moratorium on the release and commercialization of synthetic organisms pending further public debate.

Venter's team started by determining the precise order of all 580,076 base pairs, or "letters" of DNA code, inside one of the simplest microbes known to science: Mycoplasma genitalium, a bacterium that can infect the human genital tract. The scientists bought small pieces of DNA, then perfected painstaking methods to stitch them together inside bacteria and yeast cells in exactly the right order.

The final product -- 582,970 base pairs in all -- is a near-exact replica of M. genitalium's genome, with a few intentional differences. The team omitted a DNA snippet that allows the microbe to infect other cells, for example, and added extra DNA as "watermarks" to differentiate their construct from the naturally occurring variety.

"It's the first synthetic bacterial chromosome," Venter said. "Every one of those base pairs started as a chemical in a bottle."

George Church, a Harvard geneticist leading competing efforts to develop novel life forms -- not from scratch but by modifying existing bacteria -- said the work marks something less than the dawn of a new era.

"This is not a 'creating life' paper. It is not a test of vitalism. It's an assembly paper," Church said. "The question is: Is it faster or cheaper than other methods? But they don't lay out their economics. They missed an opportunity there."

Venter said he could not provide an estimate of the project's cost.

Venter and others have already made synthetic genomes for viruses, which are about one-hundredth the size of bacterial genomes. Some activists contend that synthetic bacteria pose more dangers because, unlike viruses, they can replicate on their own and can survive a long time in the environment.

Venter said the work was green-lighted by government offices, the National Academies and an independent ethics review board.

Scientists Find Solar System Like Ours

By DENNIS OVERBYE
Published: February 14, 2008

Astronomers say they have found a miniature version of our own solar system 5,000 light years across the galaxy — the first planetary system that really looks like our own, with outer giant planets and room for smaller inner planets.

The discovery, they said, means that our solar system might be more typical of planetary systems across the universe than had been thought.

“It looks like a scale model of our solar system,” said Scott Gaudi of Ohio State University. He led an international team of 69 professional and amateur astronomers, who announced the discovery in a news conference with reporters on Wednesday. Their results are being published Friday in the journal Science.

In the newly discovered system, a planet about two-thirds of the mass of Jupiter and another about 90 percent of the mass of Saturn are orbiting a reddish star about half the mass of the Sun, at about half the distances that Jupiter and Saturn circle our own Sun.

Neither of the two giant planets is a likely abode for life as we know it, but, as Dr. Gaudi pointed out, warm, rocky planets — suitable for life — could exist undetected in the inner parts of the system. “This could be a true solar system analogue,” he said.

Sara Seager, a theorist at the Massachusetts Institute of Technology who was not part of the team, said, “Right now in exoplanets we are on an inexorable path to finding other Earths.” She praised the new discovery as “a big step in finding out if our planetary system is alone.”

Since 1995, around 250 so-called exoplanets have been discovered, but few of them are in systems that even faintly resemble our own. In many cases, giant Jupiter-like planets are whizzing around inside the orbit of Mercury. But are these typical of the universe?

Almost all of those planets were discovered by the so-called wobble method, in which astronomers measure the gravitational tug of planets on their parent star as they whir around it. This technique is most sensitive to massive planets close to their stars.

The new discovery was made by a different technique that favors planets more distant from their star. It is based on a trick of Einsteinian gravity called microlensing. If, in the ceaseless shifting of the stars, two stars should become perfectly aligned with the Earth, the gravity of the nearer star can bend and magnify the light from the more distant one, causing it to suddenly get much brighter for a few days.

If the alignment is especially perfect, any big planets attending the nearer star will get into the act, adding their own little bumps to the more distant starlight.

That is exactly what started happening on March 28, 2006, when a star 5,000 light years away in the constellation Scorpius began to pass in front of one 21,000 light years more distant, causing it to flash. It was picked up by the Optical Gravitational Lensing Experiment, or Ogle, a worldwide collaboration of observers who keep watch for such events.

Ogle in turn immediately issued a worldwide call for continuous observations of what is now officially known as OGLE-2006-BLG-109L. The next 10 days, as Andrew Gould of Ohio State said, were “extremely frenetic.”

Among those who provided crucial data and appeared as lead authors of the paper in Science were a pair of amateur astronomers from Auckland, New Zealand, Jennie McCormick and Grant Christie, both members of a group called the Microlensing Follow-Up Network, or MicroFUN. Ms. McCormick, who described herself as “an ordinary New Zealand mother,” said she had done her observing with a 10-inch Meade telescope from a shed in her back yard.

Somewhat to the experimenters’ surprise, by clever manipulation they were able to dig out of the data not just the masses of the interloper star and its two planets but also rough approximations of their orbits, confirming the similarity to our own system. David Bennett of Notre Dame, said, “This event has taught us that we were able to learn more about these planets than we thought possible.”

As a result, microlensing is poised to become a major new tool in the planet hunter’s arsenal, “a new flavor of the month,” in the words of Dr. Seager. The new system, she said, is just the tip of the iceberg and the odds are that a lot of the ones that will be discovered could be like ours.

Only six planets, including the new ones, have been discovered by microlensing so far and the Scorpius event was the first in which the alignment of the stars was perfect enough for astronomers to detect more than one planet at once. Their success at doing just that on their first try bodes well for the future, astronomers say.

Alan Boss, a theorist at the Carnegie Institution of Washinton, said: “The fact that these are hard to detect by microlensing means there must be a good number of them — solar system analogues are not rare.”

Antarctic glacier melted more quickly last year

Fri Mar 14, 2008 1:19pm EDT
By Karina Grazina

MARAMBIO BASE, Antarctica (Reuters) - A glacier used as a benchmark to measure global warming's impact on the Antarctic Peninsula melted more than usual in the past year, according to an Argentine glacier researcher.

For more than 20 years, Pedro Skvarca has studied the Devil's Bay glacier on Vega Island off the Antarctic Peninsula, a part of Antarctica that is warming five times faster than the average in the rest of the world.

The whole of Antarctica holds enough ice and snow to raise world sea levels by 187 feet if it all melted over thousands of years, according to U.N. data.

Skvarca said the Devil's Bay glacier has thinned by 3.3 feet (1 meter) per year on average since his research began. But its deterioration has been unusually marked in the past year.

"We've observed a tremendous ablation (during the past year), which is really unusual," Skvarca, head of the Argentine Antarctic Institute's Glaciology Division, told Reuters in an interview at Argentina's main center for studying Antarctica, the Marambio base.

Ablation is the melting and falling away of ice in the zone at the foot of a glacier.

"(Last year) I put a box with a thermometer in it next to a marker that was level with the top of the ice. I found it half a meter in the air hanging from a wire," he said last week.

ICE MASSES

Skvarca said the glacier at Devil's Bay was the only Antarctic glacier to have its mass balance tracked consistently in recent years.

Mass balance is the difference between what is added to a glacier from snow or ice accumulation in the winter and what is melted or falls away in the summer.

"This is important because if you add up the mass balance of all the world's glaciers, we have very clear indications that we're in a period of atmospheric warming and receding glaciers," he said as he prepared to take a military flight home at the end of his annual studies during the Southern Hemisphere's summer.

The Antarctic Peninsula, which stretches from Antarctica toward South America, is considered an important area for studying climate change because of the effect it has had on the continent's ice masses.

Some of the huge ice shelves that line the peninsula's coasts have disintegrated, floating in chunks in the ocean.

A large part of the Larsen ice shelf broke off in 1995. In 2002, another section floated away, creating a 500 billion tonne iceberg as big as Luxembourg.

Ice shelves, which lie on top of the sea and are attached to land, are present along more than 40 percent of the Antarctic coastline. They are key to the stability of glaciers since they stop them from falling into the sea.

Skvarca is now closely watching the evolution of glaciers that once fed into the Larsen ice shelves.

"We're seeing the first signs of how the break-up of the shelves affects the glaciers that feed them," he said.

(Reporting by Karina Grazina; Translated by Fiona Ortiz)

Quasars: One hell of a blast

Quasars are the most destructive forces in the universe – and a newly discovered one could be the most powerful of all. David Whitehouse unravels its mysteries

Wednesday, 9 April 2008


An image of the newly discovered quasar named J081102, perhaps the most destructive ever found ESA

It looks like an image from a Star Wars film – the destruction of the Death Star, perhaps. But in fact this is real. Published yesterday by the European Space Agency, it shows a vast quasar destroying a galaxy far, far away. It's certainly among the most powerful quasars ever discovered, and if, as thought, it proves to be the mightiest of all, then this image will represent the most awesome force ever witnessed in the universe.

Of all the strange objects in the heavens, quasars are among the most fascinating. Thought to number about 100,000 in total, they are among the most mysterious, distant and significant objects in the universe. First discovered in the 1950s, they are scenes of cataclysmic violence. They are also the most distant objects we have ever seen. When the universe was young, quasars were common, but due to the extraordinary distances involved, and the time their light takes to reach us, we can still see them, burning bright. Thankfully, quasars do not occur today. If they did, we wouldn't be here.

A quasar consists of a black hole surrounded by super-heated gas that gives off prodigious amounts of radiation. Just to hint at the scales involved, the black hole at the centre of the quasar pictured here is a billion times the mass of our own Sun. Quasars begin life as distant galaxies, and eventually they collapse, and the galaxy and gas is swallowed by the black hole.

For astronomers, the new observations of quasars allow them to explore not only extremes of matter but also the evolution of the universe as it made the transition from its violent youth.

The orbiting observatory used to capture this latest image is called XMM-Newton. It was launched in 1999 and it detects X-rays, which are high-energy radiation waves that come from the hot and violent parts of the cosmos – from such things as exploding stars that tear themselves asunder, when for a few days a single star can outshine a hundred billion of its companions, and also from quasars, where the radiation is emitted by matter as it is drawn into a giant black hole.

Quasars were first glimpsed in the 1950s, when radio astronomers were carrying out the first surveys of the sky using radio telescopes. They noticed that there were many points emitting radiation, and were keen to see whether they could see the sources with conventional optical telescopes. Some of the radio waves seemed to be coming from ordinary stars, which in itself was a puzzle, but it was nothing to what would later be found out. A closer look at these "stars" changed the course of astronomy and our understanding of the universe.

The story is part of astronomical folklore. Two astronomers, Jesse Greenstein and Maarten Schmidt of the California Institute of Technology, had been using the largest telescope in the world at the time (the 200-inch reflector on Palomar Mountain in California) to peer at the object glowing in the exact position of 3C48 – the 48th object catalogued in the third Cambridge radio survey of the sky. It seemed to be a star and was called a "quasi-stellar object" or quasar.

Greenstein looked at the photograph that contained the image of the object and noticed that it appeared to be at an incredible distance. "Four billion light-years," he said (the nearest star, for comparison, is only four light-years away). Schmidt did not believe him. Could this object be the most distant object ever seen? He redid the calculations. Greenstein was right. This was no star at all! What had at first seemed to be a star and therefore thought to be very close by in cosmic terms, turned out in reality to be on the other side of the universe. This meant that they had to be pouring out so much light that they challenged what was then understood about energy and matter.

The race was then on to find more quasars, and they came, further and further away, radiating seemingly impossible energies. One or two of them were so bright that they could even be detected with an amateur astronomer's backyard telescope. Since then, astronomers have found many quasars and they are recognised as being a vital probe into the evolution of the cosmos. They are part of the early universe, a passing phase when the cosmos was young.

That is why they are so far away – when we look at the farthest reaches of space we are seeing back into earlier epochs because of the time it takes the light to reach us.

Today they are believed to be a feast happening at the edge of the universe when an enormous black hole devours vast clouds of gas, stars and even entire galaxies.

The idea is that when the universe was young and the first galaxies were being born, black holes formed at their cores. A black hole is an object from which nothing can escape and which will get larger as it swallows more matter, so being positioned at the centre of a galaxy is good, for there is a plentiful supply of matter.

As matter – represented by the green streaks in the picture on the right – falls into the black hole, it collects in a swirling reservoir called the accretion disc – the orange belt in the picture – which heats up to many millions of degrees. There is no place in nature as violent or extreme as matter swirling around a black hole and it is a prodigious source of X-rays. Most of the material spirals down into the black hole and when it passes the so-called event horizon it disappears from our universe, for what enters a black hole is lost for ever. However, computer simulations suggest that powerful radiation and magnetic fields present in the region can eject some of the gas from the gravitational clutches of the black hole, throwing it back into space along jets of matter and radiation that fly away from the black hole's spin axis.

It is this outflow that XMM-Newton has seen, and its profound effect on its surrounding galaxy. It can create turbulence in the gas throughout the galaxy, destroying star fields. Thus, understanding quasars is an important step to understanding the early history of galaxies. The latest observations used XMM-Newton to target four such powerful quasars, looking at the way the X-rays from the superhot accretion disc could be affected by the galaxy around the black hole. Two of them emitted more X-rays than anticipated, indicating that there is no veil of absorbing gas surrounding these particular quasars allowing a rare peek into the inner recess of the galaxy and the workings of the black hole.

It is thought that when a galaxy such as ours was young, a quasar could have been alight at its core and the harsh radiation it sent out would have prevented any life as we know it from developing. Only now, billions of years later, when the quasar has turned off, can we possibly exist here.

Today, astronomers can peer at the heart of our galaxy and see evidence for a super-massive black hole. These days it is quiescent, slumbering because it is no longer being fed with a steady diet of gas and stars. But should that ever change, a quasar could once more blaze forth, with jets of intense radiation rendering our galaxy uninhabitable. This is why we need to study quasars: they are wonderful and horrible.

Human warming hobbles ancient climate cycle

By Deborah Zabarenko, Environment Correspondent

WASHINGTON (Reuters) - Before humans began burning fossil fuels, there was an eons-long balance between carbon dioxide emissions and Earth's ability to absorb them, but now the planet can't keep up, scientists said on Sunday.

The finding, reported in the journal Nature Geoscience, relies on ancient Antarctic ice bubbles that contain air samples going back 610,000 years.

Climate scientists for the last 25 years or so have suggested that some kind of natural mechanism regulates our planet's temperature and the level of carbon dioxide in the atmosphere. Those skeptical about human influence on global warming point to this as the cause for recent climate change.

This research is likely the first observable evidence for this natural mechanism.

This mechanism, known as "feedback," has been thrown out of whack by a steep rise in carbon dioxide emissions from the burning of coal and petroleum for the last 200 years or so, said Richard Zeebe, a co-author of the report.

"These feedbacks operate so slowly that they will not help us in terms of climate change ... that we're going to see in the next several hundred years," Zeebe said by telephone from the University of Hawaii. "Right now we have put the system entirely out of equilibrium."

In the ancient past, excess carbon dioxide came mostly from volcanoes, which spewed very little of the chemical compared to what humans activities do now, but it still had to be addressed.

This antique excess carbon dioxide -- a powerful greenhouse gas -- was removed from the atmosphere through the weathering of mountains, which take in the chemical. In the end, it was washed downhill into oceans and buried in deep sea sediments, Zeebe said.

Read On...

Hubble Captures Crashing Galaxies

Reuters
Posted: 2008-04-27 09:49:40
Filed Under: Science News

WASHINGTON (April 26) - Images of colliding galaxies show them spinning, sliding and slipping into one another, wreaking stellar destruction that will give birth to new and larger galaxies. The Maryland-based Space Telescope Science Institute released 59 new images from the Hubble Space Telescope on Thursday to celebrate the 18th anniversary of its launch.

"This new Hubble atlas dramatically illustrates how galaxy collisions produce a remarkable variety of intricate structures in never-before-seen detail," the Institute said in a statement.

"Astronomers observe only one out of a million galaxies in the nearby universe in the act of colliding. However, galaxy mergers were much more common long ago when they were closer together, because the expanding universe was smaller."

The color images, available online at http://hubblesite.org/news/2008/16, are a look back in time. It takes hundreds of millions of years for galaxies to merge and the light from their stars has traveled for hundreds of millions of years across space.

Because it orbits outside the Earth's atmosphere, Hubble's cameras can take extremely sharp images.

Its future was controversial, as it requires regular servicing by space shuttle astronauts to stay in working condition.

After the 2003 Columbia space shuttle disaster, a servicing mission initially planned for 2004 was canceled.

NASA at one point was planning to abandon the telescope, hugely popular among astronomers. After an outcry, the U.S. space agency relented and a final Hubble servicing mission is scheduled for August.

In 2013, the James Webb Space Telescope is scheduled to replace Hubble.

First dino tracks found in ancient Arabia

Footprints left by a dinosaur ‘cow’ and a herd of 11 giant sauropods

By Charles Q. Choi

LONDON - For the first time, dinosaur footprints have been found on the Arabian Peninsula.

In ancient coastal mudflats in Yemen, fossils reveal that a herd of 11 gigantic dinosaurs — sauropods, the largest animals that ever walked on land — tramped deep tracks into the earth that have lasted roughly 150 million years.

Nearby, there are tracks of a lone ornithopod — a large, common vegetarian with birdlike, three-toed feet that walked on its hind legs, sometimes referred to as the "cow of the Mesozoic," said researcher Anne Schulp of the Maastricht Museum of Natural History in the Netherlands. The Mesozoic Era is also known as the Age of Dinosaurs.

Altogether, these new tracks help shed the most light to date on the mysterious history of dinosaurs in the Arabian Peninsula. Only a few dinosaur fossils have been reported so far from the Arabian Peninsula — isolated bones from the Sultanate of Oman and possible fragments of a sauropod from the Republic of Yemen.

"No dinosaur trackways had been found in this area previously. It's really a blank spot on the map," Schulp said.

And "big dinosaurs don't live alone," Schulp told LiveScience. "I'm sure there were some carnivorous dinosaurs around as well, as well as much smaller animals, not only dinosaurs."

Just as expert trackers can learn much about their quarry today from tracks, so too can scientists discover critical details about dinosaurs. For instance, the fact that sauropods did not leave furrows from their tails with their footprints means these giants did not drag their lengthy tails behind them. Instead, they must have held them high off the ground, to help balance their bodies, given their equally long necks.

"We really want to learn when did which dinosaurs live where, and why was that?" Schulp said. "How did the distribution change over time, why did one replace another and move from one place to another?"

Found By A Journalist

The newly announced fossil tracks were discovered by a local journalist in 2003, about 30 miles (48 kilometers) north of the capital of Sana'a near the village of Madar. They probably went unnoticed for so long because they were too big to be spotted by the untrained eye and were partially covered by rubble and debris.

"It isn't a surprise that they were overlooked," Schulp said.

The site preserved footprints from 11 small and large sauropods. Judging by the lengths of their strides and details of their footprints, they were each ambling together at the same speed of roughly 1.8 mph (3 kilometers per hour). These serve as an excellent example of dinosaur herding behavior, the researchers said.

"It's rare to see such a big example of a dinosaur herd. This is interesting social behavior for reptiles," Schulp said. "I'm really excited by finding out that the whole herd is walking at the same speed, with the younger ones having to walk a bit quicker — making short steps at a higher frequency — and the big ones walking at the same speed with long steps at a lower frequency. It just works out wonderfully well."

The ornithopod left 15 footprints, each averaging 22 inches (56 centimeters) long and wide, or the equivalent of a size-44 U.S. men's shoe. Judging by its footprints, it was traveling at "a leisurely walking speed of 3 to 4 kph (1.8 to 2.5 mph)," Schulp explained.

Unusual Find

Although ornithopods and sauropods overlapped in time, it is a bit unusual to find evidence of such a big ornithopod in the late Jurassic, the epoch from which these fossils date, the researchers noted. Back then, the African and Arabian Peninsular land masses had not yet been separated by the Red Sea.

"These trackways help us to assemble a more detailed picture of what was happening on the southern landmasses. It's exciting to see new paleontological data coming out of Yemen, and I think there is a lot more to discover," said researcher Nancy Stevens, an Ohio University paleontologist. "This international collaboration provides an exciting new window into evolutionary history from a critically undersampled region."

This area could readily yield more trackways, the researchers added.

"I'm absolutely sure we've only scratched the surface yet," Schulp said. "There is much more to be discovered in the area, much more to be learned. I hope we can build on this fieldwork and go out searching for more tracks in the not-too-distant future."

These trackways do "represent a new frontier," said Martin Lockley, curator and director of the University of Colorado at Denver's fossil footprint collection, who did not participate in this study. "People haven't really looked for dinosaur tracks very much in the Middle East. My guess is these finds are just the tip of the iceberg — maybe not the best metaphor for the Arabian Peninsula, but still, I expect there's a lot to be found there."

The Yemen Geological Survey is now preserving this area and plans to improve its accessibility to tourists. "It's a wonderful piece of geological heritage, and something well worth visiting," Schulp said.

Schulp, Stevens and their colleague Mohammed Al-Wosabi will detail their findings online May 21 in the journal PLoS ONE.

Partial funding for the research was provided by the Yemen Geological Survey and Ohio University.

Dark, Perhaps Forever

By DENNIS OVERBYE
Published: June 3, 2008



BALTIMORE — Mario Livio tossed his car keys in the air.

They rose ever more slowly, paused, shining, at the top of their arc, and then in accordance with everything our Galilean ape brains have ever learned to expect, crashed back down into his hand.

That was the whole problem, explained Dr. Livio, a theorist at the Space Telescope Science Institute here on the Johns Hopkins campus.

A decade ago, astronomers discovered that what is true for your car keys is not true for the galaxies. Having been impelled apart by the force of the Big Bang, the galaxies, in defiance of cosmic gravity, are picking up speed on a dash toward eternity. If they were keys, they would be shooting for the ceiling.

“That is how shocking this was,” Dr. Livio said.

It is still shocking. Although cosmologists have adopted a cute name, dark energy, for whatever is driving this apparently antigravitational behavior on the part of the universe, nobody claims to understand why it is happening, or its implications for the future of the universe and of the life within it, despite thousands of learned papers, scores of conferences and millions of dollars’ worth of telescope time. It has led some cosmologists to the verge of abandoning their fondest dream: a theory that can account for the universe and everything about it in a single breath.

“The discovery of dark energy has greatly changed how we think about the laws of nature,” said Edward Witten, a theorist at the Institute for Advanced Study in Princeton, N.J.

This fall, NASA and the Department of Energy plan to invite proposals for a $600 million satellite mission devoted to dark energy. But some scientists fear that might not be enough. When astronomers and physicists gathered at the Space Telescope Science Institute recently to take stock of the revolution, their despair of getting to the bottom of the dark energy mystery anytime soon, if ever, was palpable, even as they anticipate a flood of new data from the sky in coming years. When it came time for one physicist to discuss new ideas about dark energy, he showed a blank screen.

The institute’s director, Matt Mountain, said that dark energy had given this generation of astronomers a rare opportunity, and he admonished them to use it wisely.

“We are placing a large bet,” Dr. Mountain said, “using our credibility as collateral, that we as a community know what we are doing.”

But many stressed that it was going to be a long march with no clear end in sight. Lawrence Krauss of Case Western Reserve University told them, “In spite of the fact that you are liable to spend the rest of your lives measuring stuff that won’t tell us what we want to know, you should keep doing it.”

Scuffling in the Dark

Through myriad techniques and observations, cosmologists have recently arrived, after decades of strife, at a robust but dark consensus regarding a cosmos in which stars and galaxies, as well as the humans who gawk at them, amount to barely more than a disputatious froth. It was born 13.7 billion years ago in the Big Bang. By weight it is 4 percent atoms and 22 percent so-called dark matter of unknown identity — perhaps elementary particles that will be discovered at the Large Hadron Collider starting up outside Geneva this year. That leaves 74 percent for the weight of whatever began causing the cosmos to accelerate about five billion years ago.

As far as astronomers can tell, there is no relation between dark matter, the particles, and dark energy other than the name, but you never know. Some physicists are even willing to burn down their old sainted Einstein and revise his theory of gravity, general relativity, to make the cosmic discrepancies go away. There is in fact a simple explanation for the dark energy, Dr. Witten pointed out, one whose tangled history goes all the way back to Einstein, but it is also the most troubling.

“Dark energy has the somewhat unusual property that it was embarrassing before it was discovered,” he said.

In 1917, Einstein invented a fudge factor known as the cosmological constant, a sort of cosmic repulsion to balance gravity and keep the universe in balance. He abandoned his constant when the universe was discovered to be expanding, but quantum physics resurrected it by showing that empty space should be foaming with energy that had the properties of Einstein’s constant.

Alas, all attempts to calculate the amount of this energy come up with an unrealistically huge number, enough energy to blow away the contents of the cosmos like leaves in a storm before stars or galaxies could form. Nothing could live there.

Dr. Witten and other physicists used to think this conundrum “would somehow go away.” Something was missing in physicists’ understanding of physics, the logic went. The constant was really zero for deep reasons that, when revealed, would lead physicists closer to an understanding of what they call “the vacuum,” that is to say, the structure of reality.

“It seems now that the answer is not really zero,” Dr. Witten said.

Requiem for a Dream

Einstein’s constant is the most economical explanation for dark energy, Dr. Witten said. The others, involving new force fields or tinkering with Einstein’s gravity, are hard to make work and raise more questions than they answer. But if dark energy is the cosmological constant, it is smaller than predicted by a shocking factor of 1060. No fundamental principles can explain why Einstein’s constant, or any physical parameter, could be so small without being zero, Dr. Witten said. Zero can be a fundamental number, he said, but not a 1 with 59 zeroes between it and the decimal point.

As a result, he said, maybe physicists should give up trying to explain that number and look instead for a theory that generates all kinds of universes, a so-called multiverse.

That idea has been given mathematical form by string theory, which portrays the constituents of nature as tiny wriggling strings, an elegant idea that in principle explains all the forces of nature but in practice leads to at least 10500 potential universes.

This maze was an embarrassment for string theory. As Dr. Witten, one of the leaders of the field, said, “I am tempted to say this was an embarrassment of my youth.”

“Who needs that mess?” he recalled thinking. “There is just one world we live in.”

Now, Dr. Witten allowed, dark energy might have transformed this fecundity from a vice into a virtue, a way to generate universes where you can find any cosmological constant you want. We just live in one where life is possible, just as fish only live in water.

“This interpretation of string theory might be close to the truth,” Dr. Witten said. But that truth comes at a cost.

“Before the discovery of the dark energy, quantum physicists tended to assume that the ‘vacuum’ we live in has some deep meaning that reflects nature’s deepest secrets,” Dr. Witten said. But if ours is only one of a zillion in a haystack, there is nothing special about it, no secret to be found.

It could still turn out that dark energy is some as-yet-undiscovered “fifth force,” say, or the result of not understanding gravity. In that case, Dr. Witten said, “All the old viewpoints would be correct,” and physicists could go back to dreaming of a final theory.

“I’d be happy if that happened,” he said. “Our reward would be to go back to where we were, not understanding the cosmological constant.”

The notion that there are a zillion universes, whose individual properties are just a cosmic dice throw, is a story that has been told before and “raises the blood pressure of many physicists seriously,” as Dr. Livio put it. But the idea has rarely been mentioned by Dr. Witten, who is seen in the community as a symbol of the old Einsteinian ideal.

Dr. Witten said he was just doing his duty to explain what dark energy meant to physics.

“As for how I feel personally, I am not sure what to say,” he said in an e-mail message. “I wasn’t terribly enthusiastic the first, or even second, time I heard the proposal of a multiverse. But none of us were consulted when the universe was created.”

Astronomy of the Invisible

The trouble started in 1998 when two competing teams of astronomers, one led by Saul Perlmutter of the Lawrence Berkeley National Laboratory in California and the other by Brian Schmidt of the Australian National University, discovered that the expansion of the universe was inexplicably accelerating.

Both teams were using a kind of exploding star known as a Type 1a supernova as standard candles — objects whose distance can be inferred from their apparent brightness and a few other tricks of the trade — to investigate the history and fate of the universe. They found, on the basis of a few dozen of these stars, that the more distant ones were dimmer than expected, meaning that they had been carried farther away by the cosmic expansion than expected, meaning that the universe was speeding up. The car keys were streaking for the ceiling.

The groups quibble about who saw and said what first, but they have shared in a cavalcade of awards and prizes, among them the $1 million Shaw Prize in 2006 and the $500,000 Gruber Cosmology Prize, awarded last fall at Cambridge University in England, where Dr. Perlmutter and Dr. Schmidt lectured jointly, trading sentences.

Since then myriad collaborations have joined in the hunt for these exploding stars. In Baltimore, Dr. Perlmutter reported on a new analysis of “the world’s data set,” more than 300 supernovas observed by various groups, which he said would provide the tightest constraints on the nature of dark energy “for at least the next 15 minutes.”

Dr. Perlmutter’s results, along with all the others that were presented over the next four days, were consistent with Einstein’s cosmological constant, plus or minus 10 percent, but with just about everything else the theorists can throw into the pot, as well.

Nor is there any solid evidence yet that dark energy is or is not varying with time — if it is not constant, it cannot be Einstein’s constant. Adam Riess of the Johns Hopkins space telescope institute, a key member of Dr. Schmidt’s team, said, “The biggest thing we could learn is by ruling that out.”

He added, “We have a suspect, but we’re not ready to convict anyone yet.”

Dr. Perlmutter said, “The challenge is to make dramatic improvements in the quality of the data,” adding, “The next decade should be a very fertile time.”

Astronomers have developed a smorgasbord of other ways of tracking the effect of dark energy. They have learned how to map the growth of clusters of galaxies, by analyzing how their gravity distorts the light from galaxies far behind them. Gravity makes the clusters grow; dark energy holds them back.

“We can see dark matter, and in principle even invisible clusters,” said Henk Hoekstra of the University of Victoria in Canada.

Another technique is to simply count the clusters at different times in the cosmic past, the way one might count trees to gauge the growth of a forest. Yet another method is to use sound waves from the hot, early days of the universe, which have left an imprint on the distribution of galaxies today — a 500-million-light-year “bump” — as a cosmic yardstick for measuring the universe as it grew.

Each of these methods has its own strengths and weaknesses, and experts agree that it will be necessary to marry the results from many methods to zoom in on the properties of dark energy. They also agree that the best place to do that is in space.

The Big Bake-Off

Last year a committee from the National Academy of Sciences recommended that a dark energy observatory be the next mission in an astrophysics program called Beyond Einstein.

There are now three competitors angling for the job: Dr. Perlmutter’s SNAP, for Supernova Acceleration Probe; Adept, or Advanced Dark Energy Telescope, led by Charles Bennett of Johns Hopkins; and Destiny, for Dark Energy Space Telescope, led by Tod Lauer of the National Optical Astronomy Observatory in Tucson.

Also in the works, just to add spice, is a European mission known as Euclid, which could fly in 2017, if it is approved by the European Space Agency. NASA and the Department of Energy, working together, expect to make a final selection for the dark energy mission — known colloquially as J-dem for Joint Dark Energy Mission — next spring and launch it in the middle of the next decade.

That sounds like progress, but some astronomers, including the former members of the academy committee itself, have complained that $600 million is less than half of the $1.2 billion to $1.5 billion the academy committee estimated was necessary to do the job. In a recent letter to Michael Salamon, NASA scientist in charge of the project, 11 of the committee members, including both of its chairmen, urged NASA to raise the cost cap on the mission, writing, “Cutting the budget in half would probably make the attainment of these goals impossible.”

NASA’s $600 million does not include the cost of launching the satellite, so the discrepancy is not as big as it looks. But in Baltimore, Jon Morse, director of astrophysics at NASA headquarters, warned that if the astronomers wanted to spend a billion dollars, some other astronomy mission would have to come off the table.

NASA has to live within its means, Dr. Morse said in an interview.

“Otherwise,” he said, “Beyond Einstein becomes beyond reality.”

A Hole in the Future?

Whatever proposal is eventually selected, the dark energy satellite will return a tidal wave of data about the universe and its weird denizens, both visible and invisible. This data is likely to transform astronomy in unpredictable ways, but there is no guarantee that it will nail the mystery of dark energy.

Both alternatives to the constant — some weird energy field in space, or a modification to Einstein’s theory of gravity — could vary wildly over the course of history. But Paul Steinhardt, a theorist from Princeton University, argued that they would tend to mimic the cosmological constant so closely that the different models cannot be distinguished within the projected error limits, of a few percent.. He called this blur of ignorance “the J-dem hole.” The specter of the J-dem hole dominated a panel discussion later in the week devoted to the question, “How well do we have to do?”

The answer, said Dr. Krauss of Case Western, was “better than you will be able to do.”

The only real job, he said, is to distinguish dark energy from the cosmological constant. “If we don’t answer that question, we won’t have learned a thing,” Dr. Krauss said.

He compared the present situation with the development of quantum mechanics, the paradoxical sounding rules that govern inside the atom, which overturned science in the 1920s.

That revolution, he pointed out, stemmed from theorists’ inability to explain the so-called black body radiation emitted from a hot glowing object. The solution did not come from more and more precise measurements of the black body spectrum, but rather from the heads of people like Niels Bohr and Werner Heisenberg, who envisioned new ways that atoms could work and weird new laws of nature.

“We really need new theory, and we have none,” Dr. Krauss said.

In the meantime, astronomers could get lucky. Despite Dr. Steinhardt’s analysis, measurements of dark energy’s strength could converge on a value not quite the same as Einstein’s constant. Or it could turn out that it has changed over cosmic time and is not constant. Einstein and Dr. Witten would be off the hook.

Michael Turner, a University of Chicago cosmologist who coined the term “dark energy,” said you could measure the health of a field by the big questions it takes on, and addressing Dr. Morse of NASA, who was moderating the discussion, as well as his colleagues, he said, “You have a job, to go knock on everyone’s door and say this is the opportunity of a lifetime.”

Dr. Krauss said, “It would be crazy to talk ourselves out of this.”

He added: “You have to do what you can. You would be crazy not to look.”

Arctic ice bigger than 2007, but thawing long-term

Wed Jul 30, 2008 8:18am EDT

By Alister Doyle, Environment Correspondent

OSLO (Reuters) - Arctic sea ice is unlikely to shrink below a 2007 record low this year in a reprieve from the worst predictions of climate change even though new evidence confirms a long-term thaw is under way, experts said.

The 2007 record raised worries of a melt that could leave the North Pole ice-free this year, threaten indigenous hunters and thaw ice vital for creatures such as polar bears. It would also help open the Arctic to shipping and oil and gas firms.

"Most likely there will not be a new record minimum ice year in the Arctic this September," said Ola M. Johannessen of the Nansen Environmental and Remote Sensing Center in west Norway.

Arctic sea ice area reaches an annual summer low in September but is about 1 million square kms (386,100 sq mile) bigger than at the same time in late July 2007 at about 6 million sq kms, an area almost as big as Australia.

It is still far smaller than the average of recent decades.

"It's looking rather unlikely that we will beat the record sea ice minimum of 2007," said Mark Serreze, a senior research fellow at the U.S. National Snow and Ice Data Center (NSIDC), adding there could still be surprises.

"The North Pole is likely safe for at least this year," he said. The NSIDC had suggested in May that it was "quite possible" that the pole could be ice-free this year.

"The basic reason that while last summer saw an ideal atmospheric pattern for melting sea ice -- essentially a "perfect storm" -- the pattern so far this summer has been characterized by somewhat cooler conditions," he said.

The 2007 low area of 4.13 million sq kms shattered a 2005 record and was among factors adding pressure on governments to slow a build-up of greenhouse gases from factories, power plants and cars. Governments have agreed to negotiate a new climate treaty by the end of 2009 to succeed the U.N.'s Kyoto Protocol.

GASES RISE, ICE SHRINKS

Johannessen gave Reuters a hitherto unpublished study showing there was a 90 percent match between rising greenhouse gas emissions, mainly from use of fossil fuels, in recent decades and observations of a retreat of the ice.

"Ninety percent ... of the decreasing sea-ice extent is empirically 'accounted for' by the increasing carbon dioxide in the atmosphere," he wrote in the study, to be published next month in a journal by the Chinese Academy of Sciences.

If the match continues to hold true, the annual average ice extent would be several million km smaller by 2050 than predicted by the U.N. Climate Panel, which draws on the work of 2,500 scientists, it said.

Serreze said that he stood by a prediction that the Arctic Ocean could be ice-free in summer by 2030, decades before predictions by the Panel.

The Arctic has been warming about twice as fast as the rest of the globe in recent decades. Ice and snow reflect heat and any thaw uncovers darker ground or sea water that soak up the sun's warmth and further accelerate the melt.

Sheldon Drobot of the Colorado Center for Astrodymanics Research (CCAR), who predicted in April that there was a roughly 60 percent chance of a record 2008 Arctic melt, said he had cut chances to 40 percent and would probably revise them down again.

"Spring and summer temperatures in the Siberian coastal area are several degrees Celsius cooler in 2008 as compared to 2007," he said. "I am highly skeptical that we'll see an ice-free North Pole this year."

"Wind patterns that tend to push ice to the north have been mostly lacking this year," said James Maslanik, also at CCAR.

Birds fly north in climate change vanguard: study

Wed Jul 30, 2008 4:57am EDT

By Alister Doyle, Environment Correspondent

OSLO (Reuters) - Birds have been moving north in Europe over the past 25 years because of climate change in the vanguard of likely huge shifts in the ranges of plants and animals, scientists said on Wednesday.

A study of 42 rare bird species in Britain showed that southern European bird species such as the Dartford warbler, Cirl bunting, little egret or Cetti's warbler had become more common in Britain from 1980-2004.

And species usually found in northern Europe, such as the fieldfare, redwing or Slavonian grebe, had become less frequent in Britain.

"The species are almost certainly responding to the changing climate," said Brian Huntley of Durham University in England of a report he wrote with researchers at Cambridge University and the Royal Society for the Protection of Birds.

The study tried to filter out other factors that would affect counts of rare birds, including growing public interest that could mean more sightings. Shifts in farming, pollution, expansion of cities and conservation efforts have all affected wildlife.

Birds and butterflies are among the first to adapt to climate change because they can fly long distances to seek a cooler habitat. Other creatures and plants can take far longer if their traditional range gets too warm.

"It depends on the mobility of the species. Birds and butterflies are two of the groups where there is the best evidence that species are already showing responses to the changing climate," Huntley told Reuters of the study in Royal Society journal Biology Letters.

GREENHOUSE GASES

The shifts in the birds' ranges since 1980 were also consistent with scientists' expectations because of global warming, blamed by the U.N. Climate Panel on human use of fossil fuels in power plants, factories and cars, he said.

The panel predicted last year that warming will bring desertification, floods, melt glaciers, raise world sea levels, bring big shifts in the ranges of species and extinctions.

"This gives us greater confidence in the climate models we use for other groups of species -- butterflies, plants, reptiles and amphibians," Huntley said.

"We rarely have the opportunity to test these kinds of models. We can only wait around for 50 years and wait to see if we were correct. It's better to have historic data" as a benchmark, he said.

Why are there no green stars?

POSTED: Tuesday, July 29, 2008
FROM BLOG: Bad Astronomy Blog - An astronomer's view on science, politics, and life. Sometimes humorous, sometimes passionate, but always entertaining.

Go outside on a dark, moonless night. Look up. Is it December or January? Check out Betegeuse, glowing dully red at Orion’s shoulder, and Rigel, a laser blue at his knee. A month later, yellow Capella rides high in Auriga.

Is it July? Find Vega, a sapphire in Lyra, or Antares, the orange-red heart of Scorpius.

In fact, any time of the year you can find colors in the sky. Most stars look white, but the brightest ones show color. Red, orange, yellow, blue… almost all the colors of the rainbow. But hey, wait a sec. Where are the green stars? Shouldn’t we see them?

Nope. It’s a very common question, but in fact we don’t see any green stars at all. Here’s why.

Take a blowtorch (figuratively!) and heat up an iron bar. After a moment it will glow red, then orange, then bluish-white. Then it’ll melt. Better use a pot holder.

Why does it glow? Any matter above the temperature of absolute zero (about -273 Celsius) will emit light. The amount of light it gives off, and more importantly the wavelength of that light, depends on the temperature. The warmer the object, the shorter the wavelength.

Cold objects emit radio waves. Extremely hot objects emit ultraviolet light, or X-rays. At a very narrow of temperatures, hot objects will emit visible light (wavelengths from roughly 300 nanometers to about 700 nm).

Mind you — and this is critical in a minute — the objects don’t emit a single wavelength of light. Instead, they emit photons in a range of wavelengths. If you were to use some sort of detector that is sensitive to the wavelengths of light emitted by an object, and then plotted the number of them versus wavelength, you get a lopsided plot called a blackbody curve (the reason behind that name isn’t important here, but you can look it up if you care — just set your SafeSearch Filtering to "on". Trust me here). It’s a bit like a bell curve, but it cuts off sharply at shorter wavelengths, and tails off at longer ones.

Here’s an example of several curves, corresponding to various temperatures of objects (taken from online lecture notes at UW):

http://api.blogburst.com/ImageProxy.ashx?u...2fblackbody.jpg

The x-axis is wavelength (color, if you like) color, and the spectrum of visible colors is superposed for reference. You can see the characteristic shape of the blackbody curve. As the object gets hotter, the peak shifts to the left, to shorter wavelengths.

An object that is at 4500 Kelvins (about 4200 Celsius or 7600 F) peaks in the orange part of the spectrum. Warm it up to 6000 Kelvin (about the temperature of the Sun, 5700 C or 10,000 F) and it peaks in the blue-green. Heat it up more, and the peaks moves into the blue, or even toward shorter wavelengths. In fact, the hottest stars put out most of their light in the ultraviolet, at shorter wavelengths than we can see with our eyes.

Now wait a sec (again)… if the Sun peaks in the blue-green, why doesn’t it look blue-green?

Ah, this is the key question! It’s because it might peak in the blue-green, but it still emits light at other colors.

Look at the graph for an object as hot as the Sun. That curve peaks at blue-green, so it emits most of its photons there. But it still emits some that are bluer, and some that are redder. When we look at the Sun, we see all these colors blended together. Our eyes mix them up to produce one color: white. Yes, white. Some people say the Sun is yellow, but if it were really yellow to our eyes, then clouds would look yellow, and snow would too (all of it, not just some of it in your back yard where your dog hangs out).

OK, so the Sun doesn’t look green. But can we fiddle with the temperature to get a green star? Maybe one that’s slightly warmer or cooler than the Sun?

It turns out that no, you can’t. A warmer star will put out more blue, and a cooler one more red, but no matter what, our eyes just won’t see that as green.

The fault lies not in the stars (well, not entirely), but within ourselves.

Our eyes have light-sensitive cells in them called rods and cones. Rods are basically the brightness detectors, and are blind to color. Cones see color, and there are three kinds: ones sensitive to red, others to blue, and the third to green. When light hits them, each gets triggered by a different amount; red light (say, from a strawberry) really gets the red cones juiced, but the blue and green cones are rather blasé about it.

Most objects don’t emit (or reflect) one color, so the cones are triggered by varying amounts. An orange, for example, gets the red cones going about twice as much as the green ones, but leaves the blue ones alone. When the brain receives the signal from the three cones, it says "This must be an object that is orange." If the green cones are seeing just as much light as the red, with the blue ones not seeing anything, we interpret that as yellow. And so on.

So the only way to see a star as being green is for it to be only emitting green light. But as you can see from the graph above, that’s pretty much impossible. Any star emitting mostly green will be putting out lots of red and blue as well, making the star look white. Changing the star’s temperature will make it look orange, or yellow, or red, or blue, but you just can’t get green. Our eyes simply won’t see it that way.

That’s why there are no green stars. The colors emitted by stars together with how our eyes see those colors pretty much guarantees it.

But that doesn’t bug me. If you’ve ever put your eye to a telescope and seen gleaming Vega or ruddy Antares or the deeply orange Arcturus, you won’t mind much either. Stars don’t come in all colors, but they come in enough colors, and they’re fantastically beautiful because of it.

Note: this is not the end of the story. There are green objects in space, and some stars do appear green… but that’s for another post, coming soon. Promise.

We need to get prepared for four degrees of global warming, Bob Watson told the Guardian last week. At first sight this looks like wise counsel from the climate science adviser to Defra. But the idea that we could adapt to a 4C rise is absurd and dangerous. Global warming on this scale would be a catastrophe that would mean, in the immortal words that Chief Seattle probably never spoke, "the end of living and the beginning of survival" for humankind. Or perhaps the beginning of our extinction.

The collapse of the polar ice caps would become inevitable, bringing long-term sea level rises of 70-80 metres. All the world's coastal plains would be lost, complete with ports, cities, transport and industrial infrastructure, and much of the world's most productive farmland. The world's geography would be transformed much as it was at the end of the last ice age, when sea levels rose by about 120 metres to create the Channel, the North Sea and Cardigan Bay out of dry land. Weather would become extreme and unpredictable, with more frequent and severe droughts, floods and hurricanes. The Earth's carrying capacity would be hugely reduced. Billions would undoubtedly die.

Watson's call was supported by the government's former chief scientific adviser, Sir David King, who warned that "if we get to a four-degree rise it is quite possible that we would begin to see a runaway increase". This is a remarkable understatement. The climate system is already experiencing significant feedbacks, notably the summer melting of the Arctic sea ice. The more the ice melts, the more sunshine is absorbed by the sea, and the more the Arctic warms. And as the Arctic warms, the release of billions of tonnes of methane – a greenhouse gas 70 times stronger than carbon dioxide over 20 years – captured under melting permafrost is already under way.

To see how far this process could go, look 55.5m years to the Palaeocene-Eocene Thermal Maximum, when a global temperature increase of 6C coincided with the release of about 5,000 gigatonnes of carbon into the atmosphere, both as CO2 and as methane from bogs and seabed sediments. Lush subtropical forests grew in polar regions, and sea levels rose to 100m higher than today. It appears that an initial warming pulse triggered other warming processes. Many scientists warn that this historical event may be analogous to the present: the warming caused by human emissions could propel us towards a similar hothouse Earth.

But what are we to do? All our policies to date to tackle global warming have been miserable failures. The Kyoto protocol has created a vast carbon market but done little to reduce emissions. The main effect of the EU's emissions trading scheme has been to transfer about €30bn or more from consumers to Europe's biggest polluters, the power companies. The EU and US foray into biofuels has, at huge cost, increased greenhouse gas emissions and created a world food crisis, causing starvation in many poor countries.

So are all our efforts doomed to failure? Yes, so long as our governments remain craven to special interests, whether carbon traders or fossil fuel companies. The carbon market is a valuable tool, but must be subordinate to climatic imperatives. The truth is that to prevent runaway greenhouse warming, we will have to leave most of the world's fossil fuels in the ground, especially carbon-heavy coal, oil shales and tar sands. The fossil fuel and power companies must be faced down.

Global problems need global solutions, and we also need an effective replacement for the failed Kyoto protocol. The entire Kyoto system of national allocations is obsolete because of the huge volumes of energy embodied in products traded across national boundaries. It also presents a major obstacle to any new agreement – as demonstrated by the 2008 G8 meeting in Japan that degenerated into a squabble over national emission rights.

The answer? Scrap national allocations and place a single global cap on greenhouse gas emissions, applied "upstream" – for instance, at the oil refinery, coal-washing station and cement factory. Sell permits up to that cap in a global auction, and use the proceeds to finance solutions to climate change – accelerating the use of renewable energy, raising energy efficiency, protecting forests, promoting climate-friendly farming, and researching geoengineering technologies. And commit hundreds of billions of dollars per year to finance adaptation to climate change, especially in poor countries.

Such a package of measures would allow us to achieve zero net greenhouse gas emissions by 2050, and long-term stabilisation at 350 parts per million of CO2 equivalent. This avoids the economic pain that a cap-and-trade system alone would cause, and targets assistance at the poor, who are least to blame and most need help. The permit auction would raise about $1 trillion per year, enough to finance a spread of solutions. At a quarter of the world's annual oil spending, it is a price well worth paying.

CO2 emissions must drop

By Victor J. Reilly| Guest Columnist
Sunday, July 27, 2008

The scientific community is virtually unanimous in calling for a crash program to reduce emissions of carbon dioxide and methane, the principal greenhouse gases. Here are a few words for the remaining doubters: The Arctic is our "canary in the mine" in this matter.

Recently, each year has seen a reduction from the previous year in the summer ice cover of the Arctic Ocean. What is particularly worrying is that this reduction, by itself, increases polar heating from sunlight, as ice is a far better reflector than exposed water. A further destabilizing effect is that warming of permafrost releases some of the huge quantity of methane captured there. The more ice cover lost, the more heat received and the more greenhouse gas freed -- a destabilizing downward spiral.

Most of the concern we read about is over the consequences of the resulting warming of Earth's atmosphere. However, there may be an even greater threat to our biosphere in the amount of carbon dioxide dissolved in the oceans. A rise in that gas in the atmosphere increases that dissolved in ocean water, making carbonic acid. We are familiar with that acid in carbonated water. It is a weak acid, yet it will dissolve calcium carbonate, the principal mineral in shellfish, coral and much of the plankton at the foundation of the marine food chain.

WORSE, AS THE concentration of carbon dioxide increases in the water, the formation of calcium carbonate in living organisms is hindered. At some point the weaker of those organisms will no longer be able to grow sufficiently protective body parts, and won't survive. We do not know the level of CO2 in the atmosphere that passes the point of adversely affecting the very lives of our marine species, but already we are seeing negative effects in our coral reefs.

The G-8 recently set a world goal of a 50 percent reduction in greenhouse gas emissions by 2050. This will be an extremely difficult goal to meet. For the United States, this will require major changes in our generation and use of energy, most of which is now based on coal, natural gas and oil -- all based on carbon. Congress has now failed to take action on cap-and-trade as a carbon limiter. Those rejecting the measure feared that our action would spur movement of energy-intensive industries offshore. That may be, but Americans are in no position to urge any action by China or India, for example, when we are the highest emitters of greenhouse gases in the world, per person. We must take the lead if we are to lecture others.

To reduce carbon emissions, we can set a trade value for CO2 or a tax on carbon to be burnt to achieve our part of the G-8 goal. Either will substantially increase our cost of carbon-based energy. However, we have little basis for where that carbon penalty must be set to achieve the objective.

THERE IS A recent lesson from oil in how much its price had to increase before there was significant reduction in demand. We have found that there was little effect even with tripling the price of oil (or of gasoline). It was only 15 years ago that we nearly failed to raise the gasoline tax by less than five cents a gallon, fearing its economic impact. We clearly have little to guide us in estimating what increase in carbon costs will be needed to reduce our demand for electricity. We will need to try some value and see if it needs to be increased to have the needed effect. This can take more time than we have, particularly with cap-and-trade.

In the meantime, what advice can be offered? Will our utility bills have to double or even quadruple before we reduce our demand sufficiently to begin to phase out coal based electricity? We just do not know. One thing we certainly should be doing immediately is to stop building such large houses on large lots that will require much energy to maintain. The construction industry needs a wake-up call.

With a life of about 20 years, autos can be scrapped at acceptable cost at half that age. But we think of homes as more or less permanent investments. We will try to live in them until they become an intolerable hardship. In the goal year 2050, houses and offices being built now will be barely 40 years old, hardly ready to be torn down.

We must face up to a major change coming in our lives. We can no longer ignore or to minimize what could be a catastrophe like no other.

(The writer holds a Ph.D in chemistry, and spent 40 years in the industrial chemistry field. He is retired and lives in Aiken County.)