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SCIENCE NEWS

 
 
sumac
 
Reply Tue 25 Jul, 2006 07:42 am
We need this forum, and will have it with the next iteration. In the meantime, I can't let good stuff go unposted. I have been putting it in Wildlife and Ecology, but that is too confining.

It is my hope that people will at least read these postings, and post some of their own. If it stimulates discussion, fine. If not, fine. But at least we are aware.
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sumac
 
  1  
Reply Tue 25 Jul, 2006 07:43 am
"July 25, 2006
Editorial

Drain America First

Congress's default response to the nation's manifest energy problems is to increase supply, while doing nothing to reduce demand. Earlier this year, the House rebuffed a modest effort to increase fuel economy standards while approving a bill whose main purpose is to end a long-standing federal moratorium on drilling for oil and gas on the Outer Continental Shelf. In similar spirit, the Senate today will take up a bill to open eight million more acres of the Gulf of Mexico to oil and gas drilling.

The Senate measure is narrower and less mischievous than the House bill. Yet it, too, is aimed exclusively at increasing production.

This is mind-boggling. The bill's stated purpose is to reduce fuel prices. But while the gulf may hold enough natural gas to affect the price of that commodity, the same cannot be said of oil. No matter where it looks, a country that consumes one-quarter of the world's oil supply while holding only 3 percent of the reserves will never be able to drill its way to lower oil prices, much less oil independence.

A small bipartisan group of senators ?- led by Richard Lugar, a Republican, and Jeff Bingaman and Barack Obama, both Democrats ?- will try to correct the bill's bias toward production by adding an amendment that would improve fuel efficiency for cars and light trucks.

The amendment has been carefully drawn to satisfy objections from the automakers and thus end the sterile impasse over fuel standards. But so great is Congress's appetite for the quick fix that neither this nor any other amendment that seeks a more rational approach is likely to see the light of day. The betting now is that Senate leaders will try every trick in the book to ensure the bill's unobstructed passage.

This may be good parliamentary strategy. But it will produce a terribly one-sided energy policy."


From the NYTimes? I lost the URL. Or Washington Post.
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:44 am
ttp://www.nytimes.com/2006/07/25/science/25dna.html?th&emc=th


"July 25, 2006
Scientists Say They've Found a Code Beyond Genetics in DNA

By NICHOLAS WADE

Researchers believe they have found a second code in DNA in addition to the genetic code.

The genetic code specifies all the proteins that a cell makes. The second code, superimposed on the first, sets the placement of the nucleosomes, miniature protein spools around which the DNA is looped. The spools both protect and control access to the DNA itself.

The discovery, if confirmed, could open new insights into the higher order control of the genes, like the critical but still mysterious process by which each type of human cell is allowed to activate the genes it needs but cannot access the genes used by other types of cell.

The new code is described in the current issue of Nature by Eran Segal of the Weizmann Institute in Israel and Jonathan Widom of Northwestern University in Illinois and their colleagues.

There are about 30 million nucleosomes in each human cell. So many are needed because the DNA strand wraps around each one only 1.65 times, in a twist containing 147 of its units, and the DNA molecule in a single chromosome can be up to 225 million units in length.

Biologists have suspected for years that some positions on the DNA, notably those where it bends most easily, might be more favorable for nucleosomes than others, but no overall pattern was apparent. Drs. Segal and Widom analyzed the sequence at some 200 sites in the yeast genome where nucleosomes are known to bind, and discovered that there is indeed a hidden pattern.

Knowing the pattern, they were able to predict the placement of about 50 percent of the nucleosomes in other organisms.

The pattern is a combination of sequences that makes it easier for the DNA to bend itself and wrap tightly around a nucleosome. But the pattern requires only some of the sequences to be present in each nucleosome binding site, so it is not obvious. The looseness of its requirements is presumably the reason it does not conflict with the genetic code, which also has a little bit of redundancy or wiggle room built into it.

Having the sequence of units in DNA determine the placement of nucleosomes would explain a puzzling feature of transcription factors, the proteins that activate genes. The transcription factors recognize short sequences of DNA, about six to eight units in length, which lie just in front of the gene to be transcribed.

But these short sequences occur so often in the DNA that the transcription factors, it seemed, must often bind to the wrong ones. Dr. Segal, a computational biologist, believes that the wrong sites are in fact inaccessible because they lie in the part of the DNA wrapped around a nucleosome. The transcription factors can only see sites in the naked DNA that lies between two nucleosomes.

The nucleosomes frequently move around, letting the DNA float free when a gene has to be transcribed. Given this constant flux, Dr. Segal said he was surprised they could predict as many as half of the preferred nucleosome positions. But having broken the code, "We think that for the first time we have a real quantitative handle" on exploring how the nucleosomes and other proteins interact to control the DNA, he said.

The other 50 percent of the positions may be determined by competition between the nucleosomes and other proteins, Dr. Segal suggested.

Several experts said the new result was plausible because it generalized the longstanding idea that DNA is more bendable at certain sequences, which should therefore favor nucleosome positioning.

"I think it's really interesting," said Bradley Bernstein, a biologist at Massachusetts General Hospital.

Jerry Workman of the Stowers Institute in Kansas City said the detection of the nucleosome code was "a profound insight if true," because it would explain many aspects of how the DNA is controlled.

The nucleosome is made up of proteins known as histones, which are among the most highly conserved in evolution, meaning that they change very little from one species to another. A histone of peas and cows differs in just 2 of its 102 amino acid units. The conservation is usually attributed to the precise fit required between the histones and the DNA wound around them. But another reason, Dr. Segal suggested, could be that any change would interfere with the nucleosomes' ability to find their assigned positions on the DNA.

In the genetic code, sets of three DNA units specify various kinds of amino acid, the units of proteins. A curious feature of the code is that it is redundant, meaning that a given amino acid can be defined by any of several different triplets. Biologists have long speculated that the redundancy may have been designed so as to coexist with some other kind of code, and this, Dr. Segal said, could be the nucleosome code." "
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:46 am
http://www.nytimes.com/2006/07/25/health/25rats.html?th=&emc=th&pagewanted=print

"July 25, 2006
Nice Rats, Nasty Rats: Maybe It's All in the Genes

By NICHOLAS WADE

On an animal-breeding farm in Siberia are cages housing two colonies of rats. In one colony, the rats have been bred for tameness in the hope of mimicking the mysterious process by which Neolithic farmers first domesticated an animal still kept today. When a visitor enters the room where the tame rats are kept, they poke their snouts through the bars to be petted.

The other colony of rats has been bred from exactly the same stock, but for aggressiveness instead. These animals are ferocious. When a visitor appears, the rats hurl themselves screaming toward their bars.

"Imagine the most evil supervillain and the nicest, sweetest cartoon animal, and that's what these two strains of rat are like," said Tecumseh Fitch, an animal behavior expert at the University of St. Andrews in Scotland who several years ago visited the rats at the farm, about six miles from Akademgorodok, near the Siberian city of Novosibirsk. Frank Albert, a graduate student at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, is working with both the tame and the hyperaggressive Siberian strains in the hope of understanding the genetic basis of their behavioral differences.

"The ferocious rats cannot be handled," Mr. Albert said. "They will not tolerate it. They go totally crazy if you try to pick them up."

When the aggressive rats have to be moved, Mr. Albert places two cages side by side with the doors open and lets the rats change cages by themselves. He is taking care that they do not escape to the sewers of Leipzig, he said.

The two strains of rat are part of a remarkable experiment started in the former Soviet Union in 1959 by Dmitri K. Belyaev. Belyaev and his brother were geneticists who believed in Mendelian theory despite the domination of Soviet science by Trofim Lysenko, who rejected Mendelian genetics.

Belyaev's brother was exiled to a concentration camp, where he died, but Belyaev was able to move to Siberia in 1958 and became director of the Institute of Cytology and Genetics in Novosibirsk. There he was able to study genetics in relative freedom, according to a report prepared by Dr. Fitch after a visit to the institute in 2002.

Belyaev decided to study the genetics of domestication, a problem to which Darwin gave deep attention. Domesticated animals differ in many ways from their wild counterparts, and it has never been clear just which qualities were selected for by the Neolithic farmers who developed most major farm species some 10,000 years ago.

Belyaev's hypothesis was that all domesticated species had been selected for a single criterion: tameness. This quality, in his view, had dragged along with it most of the other features that distinguish domestic animals from their wild forebears, like droopy ears, patches of white in the fur and changes in skull shape.

Belyaev chose to test his theory on the silver fox, a variant of the common red fox, because it is a social animal and is related to the dog. Though fur farmers had kept silver foxes for about 50 years, the foxes remained quite wild. Belyaev began his experiment in 1959 with 130 farm-bred silver foxes, using their tolerance of human contact as the sole criterion for choosing the parents of the next generation.

"The audacity of this experiment is difficult to overestimate," Dr. Fitch has written. "The selection process on dogs, horses, cattle or other species had occurred, mostly unconsciously, over thousands of years, and the idea that Belyaev's experiment might succeed in a human lifetime must have seemed bold indeed."

In fact, after only eight generations, foxes that would tolerate human presence became common in Belyaev's stock. Belyaev died in 1985, but his experiment was continued by his successor, Lyudmila N. Trut. The experiment did not become widely known outside Russia until 1999, when Dr. Trut published an article in American Scientist. She reported that after 40 years of the experiment, and the breeding of 45,000 foxes, a group of animals had emerged that were as tame and as eager to please as a dog.

As Belyaev had predicted, other changes appeared along with the tameness, even though they had not been selected for. The tame silver foxes had begun to show white patches on their fur, floppy ears, rolled tails and smaller skulls.

The tame foxes, Dr. Fitch reported, were also "incredibly endearing." They were clean and quiet and made excellent house pets, though ?- being highly active ?- they preferred a house with a yard to an apartment. They did not like leashes, though they tolerated them.

American researchers have suggested that the foxes be made available as pets, partly to ensure their survival should the Novosibirsk colony be wiped out by disease.

"There was a time when Soviet science was in a desperate state and Belyaev's foxes were endangered," said Ray Coppinger, a dog biologist at Hampshire College in Massachusetts who tried to obtain some of the foxes to help preserve them. But the animals seem to have left Russia only once, for Finland, in a colony that no longer survives.

There was far more to Belyaev's experiment than the production of tame foxes. He developed a parallel colony of vicious foxes, and he started domesticating other animals, like river otters and mink. Realizing that genetics can be better studied in smaller animals, Belyaev also started a study of rats, beginning with wild rats caught locally. His rat experiment was continued after his death by Irina Plyusnina. Siberian gray rats caught in the wild, bred separately for tameness and for ferocity, have developed these entirely different behaviors in only 60 or so generations.

The collection of species bred by Belyaev and his successors form an unparalleled resource for studying the process and genetics of domestication. In a recent visit to Novosibirsk, Dr. Brian Hare of the Planck Institute used the silver foxes to probe the unusual ability of dogs to understand human gestures.

If a person hides food and then points to the location with a steady gaze, dogs will instantly pick up on the cue, while animals like chimpanzees, with considerably larger brains, will not. Dr. Hare wanted to know if dogs' powerful rapport with humans was a quality that the original domesticators of the dog had selected for, or whether it had just come along with the tameness, as implied by Belyaev's hypothesis.

He found that the fox kits from Belyaev's domesticated stock did just as well as puppies in picking up cues from people about hidden food, even though they had almost no previous experience with humans. The tame kits performed much better at this task than the wild kits did. When dogs were developed from wolves, selection against fear and aggression "may have been sufficient to produce the unusual ability of dogs to use human communicative gestures," Dr. Hare wrote last year in the journal Current Biology.

Dr. Hare believes that wolves probably have the same cognitive powers as dogs, but their ability to solve social problems, like picking up human cues to hidden food, is masked by their fear. Dogs, after their fear is removed by domestication, see humans as potential social partners, not as predators, and are ready to interact with them. But though selection for tameness was probably the first step in domesticating dogs, Dr. Hare said, they may well have adapted to human societies in other ways, with the smarter dogs leaving more progeny.

Although most of the tame foxes have stayed in Novosibirsk, Svante Paabo, also of the Planck Institute, recently managed to persuade the Russian researchers to let him have some of both breeds of the rats, after visiting Novosibirsk several times.

"It looked as if it would not work for a long time, but in the end we managed to build enough trust," Dr. Paabo said. He and his student, Mr. Albert, work closely with Dr. Plyusnina. Mr. Albert hopes to identify which of the rats' genes were selected for by the domestication process.

His strategy is to cross the tame rats with the ferocious rats and then score the progeny for how much of each trait they inherit. He hopes to identify 200 sites along the genome at which the tame and ferocious rats differ. If one or more of the sites correlate with tameness or fierceness in the progeny, they will probably lie near important genes that underlie one of the two traits.

The genes, if Mr. Albert finds them, would be of great interest because they are presumably the same in all species of domesticated mammal. That may even include humans. Richard Wrangham, a primatologist at Harvard, has proposed that people are a domesticated form of ape, the domestication having been self-administered as human societies penalized or ostracized individuals who were too aggressive.

Dr. Paabo said that if Mr. Albert identified the genes responsible for domestication in rats, "we would also look at those genes in humans and apes to see if they might be involved in human evolution."

Human self-domestication, if it occurred, would probably not have exactly the same genetic basis as tameness in animals. But Mr. Albert said that if he could pinpoint the genetic difference between the tame and ferocious rats, he would compare the chimp genome and the human genome to see if they showed a similar difference.

One possibility is that a handful of genes ?- perhaps even just one ?- underlie all the changes seen in domestication. A structure in the embryo of all vertebrates, known as the neural crest, is the source of cells that constitute much of the face, skull and pigment cells, and many parts of the peripheral nervous system and endocrine system. If the genes in the neural crest cells were delayed just a little in coming into action, a whole range of tissues could be affected, including the maturation of the adrenal glands that underlies the first fear response of young animals, Dr. Fitch has written.

Could a single gene that affects the timing of neural crest cell development underlie the whole phenomenon of animal and human domestication? "There would be one happy science Ph.D. student if that were true," Mr. Albert said.""
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:47 am
http://www.washingtonpost.com/wp-dyn/content/article/2006/07/24/AR2006072400951.html?referrer=email


"Growing Coalition Opposes Drilling
In N.M. Battle, Hunters Team With Environmentalists

By Juliet Eilperin
Washington Post Staff Writer
Tuesday, July 25, 2006; A01


VALLE VIDAL, N.M. -- Calving season has just ended in lush Carson National Forest, a fact that becomes obvious as three baby elk emerge from the woods with their mother in the midday sun. They are the newest members of a herd that has lived here for thousands of years, interrupted only at the beginning of the past century when humans killed them off -- and then promptly reintroduced them.

The natural beauty of this area of the forest, known as Valle Vidal, remained largely unblemished as the 101,000-acre mix of scenic conifer forests and open meadows became a sporting playground for Hollywood stars and moguls, and later for oil company executives, before the land was donated to the government in 1982 by Pennzoil Corp. and opened to the public.

Now, Valle Vidal has become a battleground in the drive to expand energy exploration on public land, attracting the attention of a growing coalition of hunters, anglers, environmentalists, ranchers, homeowners and politicians across the ideological spectrum.

Here and elsewhere in the Western United States, this coalition is starting to resist the push for energy exploration in some of the nation's most prized wilderness areas. Although it remains unclear how successful they will be, these new activists -- including many who treasure Valle Vidal as a place to fish for cutthroat trout, hunt for elk and ride horses across its wide expanses -- have brought a new dynamic to the public debate over energy development in the West.

"There's clearly a headlong rush into opening up these areas, but there's a recognition there's precious areas, beautiful landscapes that people appreciate and love," said Rep. Tom Udall (D-N.M.). "In those cases, the equation swings over to protection."

Udall sponsored legislation to make Valle Vidal off-limits to oil and gas drilling and to protect hundreds of thousands of acres of wilderness in California, Idaho and Oregon. The House unanimously approved Udall's bill on Monday, and the issue is now before the Senate.

In two other states, prominent GOP senators -- Conrad Burns (Mont.) and Craig Thomas (Wyo.) -- have also pushed in the past month to restrict energy exploration on public land.

The debate over Valle Vidal began in 2002 when El Paso Corp. announced it wanted to explore drilling for coal-bed methane, which involves tapping into beds of coal and extracting water to release the trapped natural gas. The Forest Service must decide whether to allow it.

The U.S. government has already opened to drilling 85 percent of the federal oil and gas reserves in the Rocky Mountains' five major energy basins. Responding in part to increased demand and rising energy costs, in 2005 the administration issued almost twice as many drilling permits -- 7,018 -- as President Bill Clinton did in 2000.

But now resistance to drilling is growing, especially because environmentalists have enlisted sportsmen and other new allies in their fight, and because energy companies already have access to most of the public land in the Rocky Mountain West. In the case of Valle Vidal, two of the groups fighting hardest to preserve it are hunters, who vie for a once-in-a-lifetime state permit to shoot elk here, and devotees of the Philmont Scout Ranch, which is next to Valle Vidal and brings 3,000 Boy Scouts there to hike each year.

"Something is happening here," said Chris Wood, vice president for conservation at the advocacy group Trout Unlimited. "What we're seeing is the emergence of a powerful new voice in conservation. It's not your garden-variety environmental groups. It's hunters and anglers and outfitters and guides that are helping convince Democrats and Republicans alike of the need to protect these last places."

Steven Belinda, energy policy initiative manager at the Theodore Roosevelt Conservation Partnership, a sporting group, shot an elk with his bow in Valle Vidal two years ago and is now mobilizing hunters to oppose drilling here. Numbering between 1,500 and 2,700, the forest's elk herd is one of the largest in the state, and a ban on off-road vehicles allows hunters to pursue the animals without the disruptive background noise.

"While I was hunting, I didn't have to worry about anyone coming in on me or all-terrain vehicles," Belinda said. "It was incredible."

El Paso officials have not said whether they would go ahead with drilling in Valle Vidal, and a decision to allow energy exploration might well attract competitors. But spokesman Bruce Connery said El Paso would probably model any operation on the coal-bed methane project it operates on Ted Turner's Vermejo Park Ranch, adjacent to Valle Vidal. Turner, who bought the surface rights to the ranch, negotiated environmental restrictions that include quieter electric pumps, buried power lines and a limit on how many people can be on the land at the same time.

Connery called the Vermejo Park operation "one of the most ecologically friendly" development projects in the nation. "The Valle Vidal is obviously a very special place. If it is developed, it needs to be done carefully," he said.

But Rep. Heather A. Wilson (R-N.M.), who signed on to Udall's bill late last month, said she could not reconcile drilling with Valle Vidal's value to the public for recreation.

"We're an energy-producing state. We're also a beautiful state," Wilson said. "The road network that serves the wellhead is not compatible with the wilderness experience."

In other parts of the West, newer residents who have arrived seeking a closer connection to nature have also voiced objections to oil and gas drilling. Sen. Thomas recently toured a housing development in Wyoming's Teton County where constituents challenged a pending gas lease sale on nearby forest land. Afterward, he questioned whether the government should allow drilling on most forested areas in the state.

"These neighbors don't want to have a gas well" nearby, Thomas said in an interview. "I understand that." He added that while public land can be used for several purposes, Americans are reacting negatively to the increased drive for energy out West. "With more development taking place, there's more pressure on the land," Thomas said.

Montana's Sen. Burns, who has long backed energy exploration on public land and just added $27 million to the Bureau of Land Management's permitting budget, recently put language in an Interior Department spending bill to block any new federal oil and gas leases on the Rocky Mountain Front. It would permanently retire leases that energy companies donate or sell to conservation groups. His proposal covers 356,000 acres, including a part of the Lewis and Clark National Forest in his state that the Blackfeet Indian Nation holds sacred.

In some cases, federal officials are trying to reconcile the administration's support for increased domestic energy production with intense local opposition to exploration.

Carson National Forest officials are working to develop by the end of the summer their first official plan to manage Valle Vidal before they decide whether to allow El Paso to begin exploration, and they received 54,028 public comments in three months. Only nine comments supported drilling for gas, and 51 percent of New Mexico residents who wrote in identified themselves as hunters and anglers.

" 'Leave it like it is' -- that's 95 percent of what we heard," said Kendall Clark, the acting forest supervisor. "We got comments about the natural quiet there. We got comments about the darkness."

El Paso sought the administration's aid in speeding the approval process in 2003, writing to the White House Task Force on Energy Project Streamlining about the Forest Service's slow pace. The task force's director, Robert W. Middleton, did write to regional officials within a matter of weeks to ask about the process, but Clark and others said they have not been pressured to approve drilling in Valle Vidal.

New Mexico Gov. Bill Richardson, a Democrat, said Republicans may be realizing the push for energy exploration on public land carries a political cost, though Thomas said it's more a question of balance.

"The Bush administration's drill, drill, drill philosophy is really upsetting many traditional recreationalists in the West," Richardson said. "This will have political repercussions for the Republican Party in the West, and for Republican candidates."

In some cases energy companies are deciding on their own to abandon plans to drill in environmentally sensitive areas. Questar Corp., a natural gas company, just donated its leases covering 1,500 acres in Montana's Blackleaf area, part of the Rocky Mountain Front, to Trout Unlimited. Questar Executive Vice President Jay B. Neese said the company had tired of the long regulatory process for drilling there and was pursuing more profitable projects. The company is drilling in Wyoming's Upper Green River Valley, home to pronghorn antelope and other important wildlife species, as well as in Colorado, Louisiana, Oklahoma, Texas and Utah.

"We pretty much had moved on, and that was not an area we were interested in," Neese said. "It didn't really affect our drilling plan." "
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:53 am
http://www.livescience.com/animalworld/060724_gibbons_walking.html

Human Ancestors May Have Hit the Ground Running

By Charles Q. Choi
Special to LiveScience
posted: 24 July 2006
01:36 pm ET



New findings raise the interesting possibility that the step from a tree-dwelling ape to a terrestrial biped might not have been as drastic as previously thought.

Scientists find muscles gibbons use for climbing and swinging through trees might also help the apes run.

Humans are the upright apes, but much remains unknown as to how our ancestors first found their footing. To shed light on the past, Evie Vereecke at the University of Antwerp in Belgium and her colleagues looked at how modern cousins of humanity such as gibbons and bonobos amble.

For two months, Vereecke's team monitored how four white-handed gibbons at a local zoo strode at speeds ranging from strolls to sprints across a 13-foot-long walkway surrounded with video cameras and loaded with scientific instruments such as force plates and pressure mats.

The gibbons collaborated well, "especially when you rewarded them with some raisins," Vereecke said.

Walking vs. running

While bonobos are our closest relatives and probably have a similar anatomy to our ancestors, gibbons are the most bipedal nonhuman apes, and the researchers wanted to see whether their gaits resembled any of humans.

Walking saves energy by converting the kinetic energy from a step to potential energy as walkers move over their supporting feet, energy that is ready to get recovered back as kinetic energy when walkers move into their next step. Running, on the other hand, stores energy from each bound as elastic energy in the tendons, muscles and ligaments before it gets recycled back as recoil for the next step.

Most legged animals walk at low speeds and run, trot, hop or gallop at high speeds. By monitoring how much force the gibbons stepped down with, the researchers calculated that gibbons almost always seemed to bounce along using the energetics linked with running, even though their footfall patterns were more like those of walks, the scientists reported in the Journal of Experimental Biology.

This suggests the step for humans from a tree-dwelling ape to a terrestrial biped might not have been as drastic as previously thought, Vereecke said.

Hop on down

The bouncy energetics of running makes sense for tree-dwellers, since the stiff-legged motions often associated with walking can shake the unsteady branches the apes might find themselves on.

When it comes to how the ancestors of humans started on their legs, scientists are divided between the terrestrial theory, assuming we became bipedal through a four-legged stage on the ground, or the arboreal theory, that sees the biomechanics of climbing and swinging through trees as potential precursors for bipedalism.

These findings support the arboreal theory, although they do not exclude the terrestrial one."
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:56 am
Both of the reports below are from a paid-for subscription, so this is the best that I could get.

"US Congress starts to believe in climate change
01 July 2006

Magazine issue 2558
IN WASHINGTON DC

They are starting to believe.

A report commissioned by Congress from the National Academy of Sciences has concluded that the controversial "hockey stick" graph of global warming is real, and that the spike in temperatures has probably been caused by human activity.

The NAS report says that the past few decades have been the warmest in the past 400 years and that it is "probable" that the last 25 years have been the warmest since AD 900. Sherwood Boehlert, chairman of the House science committee, requested the report in November 2005 in response to the political debate around the work of palaeoclimatologist Michael Mann of Penn State University at University Park. Mann's work examined average temperatures over the past 1000 years. When he plotted the results they showed that for the first 900 years there was little variation - like the shaft of a hock"


"killing africa's crops

25 February 2006
From New Scientist Print Edition.

Africa's favourite crop, maize, is struggling to cope with the vagaries of a changing climate. It might even have to have to be dropped in favour of more traditional crops such as sorghum and cassava.

So says the first continent-wide study of how crop yields change with major oscillations in global climate such as El Niño and the North Atlantic Oscillation. It concludes that 20 million Africans go hungry in the years when the climate is not in their favour (Proceedings of the National Academy of Sciences, vol 103, p 3049).

In the worst case, a strong El Niño can cut maize yields by 50 per cent in southern Africa. This is worrying, says one of the study's authors, Hans Herren of the Millennium Institute in Arlington, Virginia, because droughts could become the norm. "If the global climate changes toward more El Niño-like conditions, as most models predict, African food production may be severely reduced."

There is a glimmer of hope, however. Some crops do better during El Niño events, says co-author Nils Stenseth of the University of Oslo, Norway. Sorghum often does better when maize does badly. "This is valuable information for farmers, because an El Niño event can be predicted ahead of the crop growing season."

From issue 2540 of New Scientist magazine, 25 February 2006, page 7"
0 Replies
 
sumac
 
  1  
Reply Tue 25 Jul, 2006 07:57 am
http://images.livescience.com/images/060724_mudflats_04.jpg

images.livescience.com/images/060724_mudflats_04.jpg

Wild Mudflats, Alaskan Style


By Bruce G. Marcot, Ecology Picture of the Week:

As our noisy Beaver floatplane tilts into the morning sun, we find ourselves banking over vast mudflats here in coastal southeast Alaska. Below, the river channels filigree into tendrils that look like gargantuan dendrites of some impossible neuron.

But this is just one of a plexus of river drainages that create vast mudflats along the bays and inlets and islands of the Alexander Archipelago that spreads along southeast Alaska.

What good are mudflats? Particularly here in the far north, mudflats provide essential habitat for wildlife ... including millions of shorebirds for feeding, resting, and breeding. Mudflats also support vast numbers of invertebrates -- critical parts of the food web -- such as crustaceans, worms, water boatmen, mayflies, midges, moth flies, and many other species that feed birds and fish alike.

Mudflats are wonderful environments for conducting scientific studies and discovering new and complex relationships among organisms and their environment. For example, experiments have shown that shorebirds and crabs feeding in mudflats can significantly reduce the density of their invertebrate prey but in different ways and during different seasons. And the shorebirds had their greatest effect when feeding in the muddiest mudflat but not in the sandiest mudflat.

Mudflats are also more delicate ecosystems than they may first appear. They are quite vulnerable to pollution, particularly from oil spills. Ill effects of an oil spill can last for years or even decades as the oil seeps into the mud and sand
0 Replies
 
sumac
 
  1  
Reply Fri 28 Jul, 2006 04:05 am
http://www.livescience.com/environment/060726_hybrid_scooter.html

Hybrid Scooter Would Run on Hydrogen

By Robert Roy Britt
LiveScience Managing Editor
posted: 26 July 2006
10:53 am ET



An industrial design student in The Netherlands has built a prototype scooter that is designed to be run on hydrogen.

Crijn Bouman of Delft University of Technology designed the scooter for use in inner cities.

He calls it the Fhybrid.

"The look and feel of the scooter are aimed at selling the clean technology inside," he said in a statement today.

The scooter has an electric motor powered by a (Li-)ion battery. If the Fhybrid is ever put into production, the idea is to charge the battery with a fuel-cell system, which would derive its energy from a tank of hydrogen. While scientists are working to make such systems more efficient, obtaining hydrogen (by splitting it out of water) is for now too costly to be practical. Scientists disagree whether it will ever be viable.

The prototype scooter uses a simulated fuel-cell to recharge the battery.

"A special course and various permits are required to build a hydrogen-powered engine. It wasn't possible to achieve this during the time period of my graduation project," Bouman explained. "The faculty is now trying to assemble all the necessary means to fully develop the hydrogen-powered scooter."

The scooter also recharges the battery by snagging energy during braking.

Since two-wheeled vehicles rely primarily on front-wheel braking for efficient stops, Bouman's scooter is front-wheel drive?-better to capture the braking energy, he explained.

The Fhybrid has a top speed of 40 mph. Bouman says it accelerates faster than regular scooters and could travel approximately 124 miles on a tank of hydrogen
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Reply Fri 28 Jul, 2006 04:06 am
Ancient Human Footprints Uncovered in Australia

By Ker Than
LiveScience Staff Writer
posted: 26 July 2006
04:16 pm ET



About 20,000 years ago, humans trekked along the margins of a shallow lake in Australia, leaving behind records of their passage in the soft, wet sand.

In 2003, an aboriginal woman who is likely a descendant of those early Australians stumbled across dozens of timeworn footprints in the same area. Excavations of the site have since uncovered hundreds more.

The discovery, detailed in a recent issue of the Journal of Human Evolution, represents the largest collection of Pleistocene human footprints in the world, and the only footprints from that era ever found in Australia. In total, 457 footprints have now been uncovered.

"The preservation is just remarkable," said study team member Matthew Cupper of the University of Melbourne in Australia. "You can see quite clearly how mud oozes between the toes."

The Pleistocene stretched from about 2 million to 12,000 years ago. Highlights from the era:

A series of climatic upheavals, the worldwide spread of human-like primates, or hominids;
The extinction of Neanderthals and large land mammals?-including mammoths, giant sloth and saber toothed cats;
The rise of modern humans.
Ancient errands

The footprints were found in southeastern Australia, along the shore of one of 19 dried up lakes that comprise the Willandra Lakes system.

The researchers believe the prints were made over a series of weeks or months about 20,000 years ago when the site was exposed. Males and females, ranging from children to adults, are represented, and many of them seem to be doing different things.

"Quite a few people seem to be running and heading the same way," Cupper told LiveScience. "Some of the little children were walking slower. This may suggest that there were several events represented."

Australia is thought to have first been colonized by humans about 50,000 years ago. Those who made the newfound footprints were likely the ancestors of today's Australian aborigines, the researchers say.

Then and now ...

Like most of modern Australia, the area where the tracks were found is today dry and desert-like. Yellow-white sand dunes shift across the landscape, blown by arid winds, and little rain falls.

"It's not the most attractive landscape today, but back during the last Ice Age, there was substantial [water] drainage off the Eastern Australian highlands," Cupper said. "It would have been large freshwater expanses filled with fish and crustaceans that could support a human population."

Humans weren't the only ones that passed through the area. The prints from two kangaroo hind paws are visible, as are the tracks of a baby emu, a large flightless bird similar to an ostrich. Cupper says the emu prints might be an important clue about when the human footprints were made.

"This emu is between 50 and 70 days old, so it's just a small chick," he said. "Emu's generally nest in the winter time, so it could reveal that the site was exposed in the season of spring or early summer."


http://www.livescience.com/history/060726_pleistocene_footprints.html
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Reply Fri 28 Jul, 2006 04:08 am
http://www.livescience.com/animalworld/060726_praying_mantid.html

http://images.livescience.com/images/060726_praying_mantid_01.jpg


Praying Mantids Wise to Sexual Cannibalism Risk

By LiveScience Staff

posted: 26 July 2006
02:57 pm ET



If you were a male praying mantid, the top item on your prayer list would be to survive sex.

Female praying mantids are notorious for eating males after they mate.

Now for the first time, scientists have experimentally shown that the males are hip to the risk and not too keen on being food.

The researchers toyed with the physical position of females and how hungry they were, then noted how males responded. "We know that hungry females are more likely to cannibalize and a head-on orientation makes it easier for her to attack the male with her predatory front legs," explained William Brown of SUNY-Fredonia.

The guys responded to greater risk by slowing their approach, increasing courtship behavior, and mounting from a greater?-and possibly safer?-distance, the scientists say.

"This shows that male mantids actively assess variation in risk and change their behavior to reduce the chance of being cannibalized," Brown said. "Males are clearly not complicit, and the act of sexual cannibalism in praying mantids is an example of extreme conflict between the sexes."

Brown and colleague Jonathan Lelito report their results in the August issue of the American Naturalist.

(You may have heard these insects called "praying mantis," but mantis refers to the genus Mantis. "Only some praying mantids belong to the genus Mantis," according to Gary Watkins and Ric Bessin in the University of Kentucky Department of Entomology. "Mantid refers to the entire group.")
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  1  
Reply Fri 28 Jul, 2006 04:09 am
http://www.nytimes.com/2006/07/27/us/27butterflies.html?th&emc=th


July 27, 2006
In Texas, Conditions Lead to a Rabble of Butterflies

By RALPH BLUMENTHAL

Correction Appended

GOLIAD, Tex., July 25 ?- For a moment, Carol Cullar thought she was seeing fall leaves gusting down the highway south of Quemado, Tex., on the Mexican border.

But it is blistering midsummer, Ms. Cullar, director of the Rio Bravo Nature Center in Eagle Pass, realized. And leaves would not all be flying north at two or three feet off the ground ?- car radiator height.

These were butterflies. At least 200,000 of them, she guessed, perhaps a half-million. It was an invasion, she said, "like nothing I've ever seen."

South Texas is under siege from swarms of airborne migrants: tens of millions of Libytheana bachmanii larvata ?- snout butterflies to y'all ?- along with Kricogonia lysides, or yellow sulfurs, that have taken advantage of an unusual drought-and-deluge cycle to breed in spectacular if not record profusion.

The smallish, dull-colored snouts take their name from an appendage they attach to branches to disguise themselves as leaves.

Blinded drivers who have to pick the literally low-down critters off their grilles to avoid dangerous engine overheating are less than enthralled, as are the mottephobes, who fear butterflies and moths. But lepidopterists are thrilled with the spectacle, which they predict may be only the beginning of a population explosion of snouts.

They concede, however, that it could denude considerable swaths of Texas hackberry trees and other choice caterpillar habitats, at least for a while.

"Snouts, I'm at a loss for words," wrote Joshua S. Rose, a biologist and dragonfly specialist with the World Birding Center at Bentsen-Rio Grande Valley State Park near Mission, Tex., in an e-mail message to friends Tuesday.

"They're beyond any mere collection of individual animals," Dr. Rose wrote. "Like a flock, herd, swarm or even horde, they have more in common with a geologic or climatic force, the Gulf Stream or an Arctic front. While driving, we can't dodge butterflies, we can only aim the car at the parts of the road where the density is lowest."

Lawrence E. Gilbert, professor of integrative biology and director of the Brackenridge Field Laboratory at the University of Texas, said such mass emergences were hardly known outside the Southwest, although they also occurred with another butterfly species in Africa. Dr. Gilbert filled a bucket last week with hundreds of dead snouts and sulfurs collected from a roadside near Alice, many of which never made it to the end of their two-week life span.

The phenomenon sent Mike Quinn, an entomologist with the State Parks and Wildlife Department, beelining here on Tuesday from his Austin office to track the butterfly migration.

Cellphone pressed to his ear, Mr. Quinn, 43, polled area rangers for promising sightings. He had high hopes along the reservoir at Choke Canyon State Park. "We were told this was snout central," he said. But they had since fluttered by.

"Tons? Right as we speak, or the last few days?" Mr. Quinn asked another tipster. "Let me get a specific from you. Exactly where is everywhere?"

One parks employee, Linda Lopez, tried to be helpful. "The snout ones are the little brown ones with variegated color?" she asked.

"You got it," Mr. Quinn said. "We're looking for the river of butterflies, not just the stream."

Driving a circle of perhaps 200 miles from Goliad around Choke Canyon and back, Mr. Quinn never did find a real swarm, although he was tantalized by evidence of their ubiquitous presence on the radiators of tractor-trailers, emblazoned with crazyquilt pastiches of dead-butterfly art.

But he stamped through the brush along the water, flushing clouds of snouts, sulphurs and little blues of the kind favored by Vladimir Nabokov, which all fluttered excitedly around him. He also saw considerable evidence of the stripped Celtis trees that had nurtured the caterpillars, and specks of black caterpillar droppings called frass that fertilize the vegetation and help it recover from the feeding frenzy.

"Frass happens," Mr. Quinn said.

Mr. Quinn and Dr. Gilbert said the butterfly proliferation had been set off by drought conditions that decimated the caterpillar's natural predators, followed by drenching rains that prompted hackberry trees to put out green shoots, quickly attracting the egg-laying caterpillars that could briefly thrive without enemies.

"It was a double pop," Dr. Gilbert said, two cycles in succession that reinforced the effect over the 12-day passage of egg to adult.

With insects generally suffering a 99 percent mortality rate, said Mr. Quinn?- that is, only 1 egg of 100 laid making it to maturity ?- a sudden improvement in the odds can radically disrupt the usually exquisite balance of nature.

Where, how and why the swarms migrate is less clear. Butterflies are not social creatures flying in flocks like birds but are drawn to flowers as sources of nectar and pollen.

Dr. Gilbert said that in studying migrating snouts he was struck to find that up to 95 percent were males. "The older males get most of the matings as the hatch continues," he theorized. "Then the new guys don't have a shot because of the old guys, and they just say, The hell with this, and they go."

Correction: July 28, 2006

An article yesterday about an abundance of butterflies in South Texas misstated a step in butterfly reproduction. It is the butterfly itself, not the caterpillar, that lays eggs.
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Reply Fri 28 Jul, 2006 04:11 am
http://www.nytimes.com/2006/07/27/opinion/27doran.html?ex=1154750400&en=4a4544fb12f29297&ei=5070


July 27, 2006
Op-Ed Contributor

Cold, Hard Facts

By PETER DORAN
Chicago

IN the debate on global warming, the data on the climate of Antarctica has been distorted, at different times, by both sides. As a polar researcher caught in the middle, I'd like to set the record straight.

In January 2002, a research paper about Antarctic temperatures, of which I was the lead author, appeared in the journal Nature. At the time, the Antarctic Peninsula was warming, and many people assumed that meant the climate on the entire continent was heating up, as the Arctic was. But the Antarctic Peninsula represents only about 15 percent of the continent's land mass, so it could not tell the whole story of Antarctic climate. Our paper made the continental picture more clear.

My research colleagues and I found that from 1986 to 2000, one small, ice-free area of the Antarctic mainland had actually cooled. Our report also analyzed temperatures for the mainland in such a way as to remove the influence of the peninsula warming and found that, from 1966 to 2000, more of the continent had cooled than had warmed. Our summary statement pointed out how the cooling trend posed challenges to models of Antarctic climate and ecosystem change.

Newspaper and television reports focused on this part of the paper. And many news and opinion writers linked our study with another bit of polar research published that month, in Science, showing that part of Antarctica's ice sheet had been thickening ?- and erroneously concluded that the earth was not warming at all. "Scientific findings run counter to theory of global warming," said a headline on an editorial in The San Diego Union-Tribune. One conservative commentator wrote, "It's ironic that two studies suggesting that a new Ice Age may be under way may end the global warming debate."

In a rebuttal in The Providence Journal, in Rhode Island, the lead author of the Science paper and I explained that our studies offered no evidence that the earth was cooling. But the misinterpretation had already become legend, and in the four and half years since, it has only grown.

Our results have been misused as "evidence" against global warming by Michael Crichton in his novel "State of Fear" and by Ann Coulter in her latest book, "Godless: The Church of Liberalism." Search my name on the Web, and you will find pages of links to everything from climate discussion groups to Senate policy committee documents ?- all citing my 2002 study as reason to doubt that the earth is warming. One recent Web column even put words in my mouth. I have never said that "the unexpected colder climate in Antarctica may possibly be signaling a lessening of the current global warming cycle." I have never thought such a thing either.

Our study did find that 58 percent of Antarctica cooled from 1966 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the ozone hole over that continent. These models, conspicuously missing from the warming-skeptic literature, suggest that as the ozone hole heals ?- thanks to worldwide bans on ozone-destroying chemicals ?- all of Antarctica is likely to warm with the rest of the planet. An inconvenient truth?

Also missing from the skeptics' arguments is the debate over our conclusions. Another group of researchers who took a different approach found no clear cooling trend in Antarctica. We still stand by our results for the period we analyzed, but unbiased reporting would acknowledge differences of scientific opinion.

The disappointing thing is that we are even debating the direction of climate change on this globally important continent. And it may not end until we have more weather stations on Antarctica and longer-term data that demonstrate a clear trend.

In the meantime, I would like to remove my name from the list of scientists who dispute global warming. I know my coauthors would as well.

Peter Doran is an associate professor of earth and environmental sciences at the University of Illinois at Chicago.
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sumac
 
  1  
Reply Sat 29 Jul, 2006 03:47 am
http://www.livescience.com/animalworld/060721_snake_primate.html

Fear of Snakes Drove Pre-Human Evolution

By Ker Than
LiveScience Staff Writer
posted: 21 July 2006
12:59 am ET



An evolutionary arms race between early snakes and mammals triggered the development of improved vision and large brains in primates, a radical new theory suggests.

The idea, proposed by Lynne Isbell, an anthropologist at the University of California, Davis, suggests that snakes and primates share a long and intimate history, one that forced both groups to evolve new strategies as each attempted to gain the upper hand.

To avoid becoming snake food, early mammals had to develop ways to detect and avoid the reptiles before they could strike. Some animals evolved better snake sniffers, while others developed immunities to serpent venom when it evolved. Early primates developed a better eye for color, detail and movement and the ability to see in three dimensions?-traits that are important for detecting threats at close range.

Humans are descended from those same primates.

Scientists had previously thought that these traits evolved together as primates used their hands and eyes to grab insects, or pick fruit or to swing through trees, but recent discoveries from neuroscience are casting doubt on these theories.

"Primates went a particular route," Isbell told LiveScience. "They focused on improving their vision to keep away from [snakes]. Other mammals couldn't do that. Primates had the pre-adaptations to go that way."

Harry Greene, an evolutionary biologist and snake expert at Cornell University in New York, says Isbell's new idea is very exciting.

"It strikes me as a very special piece of scholarship and I think it's going to provoke a lot of thought," Greene said.

Isbell's work is detailed in the July issue of the Journal of Human Evolution.

A new weapon

Fossil and DNA evidence suggests that the snakes were already around when the first mammals evolved some 100 million years ago. The reptiles were thus among the first serious predators mammals faced. Today, the only other threats faced by primates are raptors, such as eagles and hawks, and large carnivores, such as bears, large cats and wolves, but these animals evolved long after snakes.

Furthermore, these other predators can be safely detected from a distance. For snakes, the opposite is true.

"If you see them close to you, you still have time to avoid them," Isbell said. "Primate vision is particularly good at close range."

Early snakes killed their prey using surprise attacks and by suffocating them to death?-the method of boa constrictors. But the improved vision of primates, combined with other snake-coping strategies developed by other animals, forced snakes to evolve a new weapon: venom. This important milestone in snake evolution occurred about 60 million years ago.

"The [snakes] had to do something to get better at finding their prey, so that's where venom comes in," Isbell said. "The snakes upped the ante and then the primates had to respond by developing even better vision."

Once primates developed specialized vision and enlarged brains, these traits became useful for other purposes, such as social interactions in groups.

Seeing in 3D

Isbell's new theory could explain how a number of primate-defining traits evolved.

For example, primates are among the few animals whose eyes face forward (most animals have eyes located on the sides of their heads). This so-called "orbital convergence" improves depth perception and allows monkeys and apes, including humans, to see in three dimensions. Primates also have better color vision than most animals and are also unique in relying heavily on vision when reaching and grasping for objects.

One of the most popular ideas for explaining how these traits evolved is called the "visual predation hypothesis." It proposes that our early ancestors were small, insect eating mammals and that the need to stalk and grab insects at close range was the driving force behind the evolution of improved vision.

Another popular idea, called the "leaping hypothesis," argues that orbital convergence is not only important for 3D vision, but also for breaking through camouflage. Thus, it would have been useful not only for capturing insects and finding small fruits, but also for aiming at small, hard-to-see branches during mid-leaps through trees.

But there are problems with both hypotheses, Isbell says.

First, there is no solid evidence that early primates were committed insectivores. It's possible that like many primates today, they were generalists, eating a variety of plant foods, such as leaves, fruit and nectar, as well as insects.

More importantly, recent neuroscience studies do not support the idea that vision evolved alongside the ability to reach and grasp. Rather, the data suggest that the reaching-and-grasping abilities of primates actually evolved before they learned to leap and before they developed stereoscopic, or 3D, vision.

Agents of evolutionary change

Isbell thinks proto-primates?-the early mammals that eventually evolved into primates?-were in better position compared to other mammals to evolve specialized vision and enlarged brains because of the foods they ate.

"They were eating foods high in sugar, and glucose is required for metabolizing energy," Isbell said. "Vision is a part of the brain, and messing with the brain takes a lot of energy so you're going to need a diet that allows you to do that."

Modern primates are among the most frugivorous, or "fruit-loving," of all mammals, and this trend might have started with the proto-primates. "Today there are primates that focus on leaves and things like that, but the earliest primates may have had a generalized diet that included fruits, nectar, flowers and insects," she said.

Thus, early primates not only had a good incentive for developing better vision, they might have already been eating the high-energy foods needed to do so.

Testing the theory

Isbell says her theory can be tested. For example, scientists could look at whether primates can visually detect snakes more quickly or more reliably than other mammals. Scientists could also examine whether there are differences in the snake-detecting abilities of primates from around the world.

"You could see whether there is any difference between Malagasy lemurs, South American primates and the African and Asian primates," Isbell said.

Anthropologists have tended to stress things like hunting to explain the special adaptations of primates, and particularly humans, said Greene, the Cornell snake expert, but scientists are starting to warm to the idea that predators likely played a large role in human evolution as well.

"Getting away from things is a big deal, too," Greene said in a telephone interview.

If snake and primate history are as intimately connected as Isbell suggests, then it might account for other things as well, Greene added.

"Snakes and people have had a long history; it goes back to long before we were people in fact," he said. "That might sort of explain why we have such extreme attitudes towards snakes, varying from deification to "ophidiphobia," or fear of snakes.

Gallery: Snakes of the World
Deadly Aim: Cobras Really Do Shoot for the Eyes
Flying Snakes: New Videos Reveal How They Do It
Millions of Years Ago, Snakes Were Hip
Top 10 Deadliest Animals
Birds of Prey
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  1  
Reply Sat 29 Jul, 2006 03:50 am
http://www.livescience.com/forcesofnature/060720_wind_greatplains.html

History Suggests Major Wind Shift Could Again Bring Drought to Great Plains

By Sara Goudarzi
LiveScience Staff Writer
posted: 20 July 2006
04:17 pm ET


http://images.livescience.com/images/060720_nebraska_sand_01.jpg

Nebraska's Sand Hills might look like a place fit only for cattle grazing, but to geologists the expanse of grasslands hide sand dunes that contain a valuable record of ancient climate.

A crisscross pattern in the dunes serves as a record of changes in wind direction and shows that 800 to 1,000 years ago, during the Medieval Warm Period, the winds brought drought to that region, according to a new study.

In the spring and summer, during the growing season, southerly winds from the Gulf of Mexico bring moisture and rainfall up to the open expanse of prairie east of the Rocky Mountains, an area known as the Great Plains.

Today, the net force of southerly summer winds combined with northerly winds of winter would push the sand dunes to migrate in a southeastern direction. But the dunes don't move because they are stabilized by vegetation.

Back during the Medieval Warm Period, the dunes were not vegetated and were free to move.

The direction that the dunes moved back then, recorded in their crisscross pattern, is a result of the net force of the winds during that time. Assuming that winter winds came from the north like today, scientists were able to figure out which direction the spring and summer winds came from.

Their analysis found that spring and summer winds back then did not come from the Gulf of Mexico but instead blew from the Southwest. These warm and dry winds likely caused the drought conditions that had previously been documented for the region back then, explained study co-author David Loope of the University of Nebraska.

And what if a similar shift occurred today?

"This argues for a conservative position of water resources, because there's a possibility of a super drought," Loope told LiveScience. "Being more conservative would be the lesson here."

The study is detailed in the July 21 issue of the journal Science.

Drought Conditions Worsen in Parts of U.S.
Singing Sand Dunes: The Mystery of Desert Music
Expedition Explains Strange Antarctic Megadunes
Sand Dunes on Mars Reach Dizzying Heights
Weather 101: All About Wind and Rain


http://images.livescience.com/images/060720_nebraska_sand_00.jpg

Northward aerial view of sand dunes in the eastern Nebraska Sand Hills. The dunes, now stabilized by prairie grass, were formed only 800-1,000 years ago during droughts of the Medieval Warm Period. Credit: David Loope and Jon Mason
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  1  
Reply Sat 29 Jul, 2006 03:52 am
http://www.livescience.com/history/060720_sahara_rains.html

Sahara Desert Was Once Lush and Populated

By Bjorn Carey
LiveScience Staff Writer
posted: 20 July 2006
02:07 pm ET



At the end of the last Ice Age, the Sahara Desert was just as dry and uninviting as it is today. But sandwiched between two periods of extreme dryness were a few millennia of plentiful rainfall and lush vegetation.

During these few thousand years, prehistoric humans left the congested Nile Valley and established settlements around rain pools, green valleys, and rivers.

The ancient climate shift and its effects are detailed in the July 21 issue of the journal Science.

When the rains came

Some 12,000 years ago, the only place to live along the eastern Sahara Desert was the Nile Valley. Being so crowded, prime real estate in the Nile Valley was difficult to come by. Disputes over land were often settled with the fist, as evidenced by the cemetery of Jebel Sahaba where many of the buried individuals had died a violent death.

But around 10,500 years ago, a sudden burst of monsoon rains over the vast desert transformed the region into habitable land.

This opened the door for humans to move into the area, as evidenced by the researcher's 500 new radiocarbon dates of human and animal remains from more than 150 excavation sites.

"The climate change at [10,500 years ago] which turned most of the [3.8 million square mile] large Sahara into a savannah-type environment happened within a few hundred years only, certainly within less than 500 years," said study team member Stefan Kroepelin of the University of Cologne in Germany.

Frolicking in pools

In the Egyptian Sahara, semi-arid conditions allowed for grasses and shrubs to grow, with some trees sprouting in valleys and near groundwater sources. The vegetation and small, episodic rain pools enticed animals well adapted to dry conditions, such as giraffes, to enter the area as well.

Humans also frolicked in the rain pools, as depicted in rock art from Southwest Egypt.

In the more southern Sudanese Sahara, lush vegetation, hearty trees, and permanent freshwater lakes persisted over millennia. There were even large rivers, such as the Wadi Howar, once the largest tributary to the Nile from the Sahara.

"Wildlife included very demanding species such as elephants, rhinos, hippos, crocodiles, and more than 30 species of fish up to 2 meters (6 feet) big," Kroepelin told LiveScience.

A timeline of Sahara occupation [See Map]:

22,000 to 10,500 years ago: The Sahara was devoid of any human occupation outside the Nile Valley and extended 250 miles further south than it does today.
10,500 to 9,000 years ago: Monsoon rains begin sweeping into the Sahara, transforming the region into a habitable area swiftly settled by Nile Valley dwellers.
9,000 to 7,300 years ago: Continued rains, vegetation growth, and animal migrations lead to well established human settlements, including the introduction of domesticated livestock such as sheep and goats.
7,300 to 5,500 years ago: Retreating monsoonal rains initiate desiccation in the Egyptian Sahara, prompting humans to move to remaining habitable niches in Sudanese Sahara. The end of the rains and return of desert conditions throughout the Sahara after 5,500 coincides with population return to the Nile Valley and the beginning of pharaonic society.
Related Stories

Deserts Might Grow as Tropics Expand
Drought Conditions Worsen in Parts of U.S.
Singing Sand Dunes: The Mystery of Desert Music
Ancient People Followed 'Kelp Highway' to America
Scientists To Study Monsoon Formation

http://www.livescience.com/images/060720_sahara_map_02.jpg
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  1  
Reply Sat 29 Jul, 2006 04:12 am
http://www.washingtonpost.com/wp-dyn/content/article/2006/07/28/AR2006072801994_pf.html



On the Roof of Peru, Omens in the Ice
Retreat of Once-Mighty Glacier Signals Water Crisis, Mirroring Worldwide Trend

By Doug Struck
Washington Post Foreign Service
Saturday, July 29, 2006; A01



QUELCCAYA GLACIER, Peru -- In the thin, cold air here atop the Andes mountains, the blue ice that has claimed these peaks for thousands of years and loyally fed the streams below is now disappearing rapidly.

Mountain glaciers such as this are in retreat around the Earth, taking with them vast stores of water that grow crops, generate electricity and sustain cities and rural areas.

Farmers here say that over the past two decades they have noticed a dramatic decrease in the amount of ice and snow on their mountaintops. The steady supply of water they need to grow crops has become erratic.

"There is less water now. If there is no water, this land becomes a desert," said Benedicto Loayza, a 52-year-old farmer, standing under pear trees fed by channels dug on the mountain centuries ago to collect runoff.

Cuzco, a city of 400,000, has already resorted to periodic water rationing and started pumping from a river 15 miles away for its drinking supply. In Peru's capital, Lima, engineers have urged successive governments to drill a tunnel through the Andes and build big lagoons to ensure that the city's 8 million residents have water. Citing the expense, authorities have dawdled. Cities in China, India, Nepal and Bolivia also face drastic water shortages as the glaciers shrink.

"You can think of these glaciers as a bank account built over thousands of years," said Lonnie Thompson, one of the first scientists to sound the alarm, as he stood by the largest ice cap in the Andes. "If you subtract more than you gain, eventually you go bankrupt. That's what's in process here."

Thompson arrived at the blue-white face of the Quelccaya glacier this month after a two-day hike from the nearest road, climbing into the oxygen-thin air of 17,000 feet above sea level. Since he started his annual visits here in 1974, he said, the huge ice cap has shrunk by 30 percent. In the last year, the tongue of the ice has pulled back 100 yards, breakneck speed for a glacier.

He examined it as if it were a sick patient. The mountain of ice was pocked with holes where the surface had melted. A large chunk had broken off in March, crashing into the meltwater lake below and sending a flood wave into alpacas' lower grazing grounds. The face of the glacier, once frozen so perfectly that Thompson could identify the yearly snowfalls back 1,500 years, now sagged and dripped.

"It's not just a retreat," he said. "It's an accelerating retreat."

Since Thompson's first reports, he and others have confirmed a rapid recession of glaciers worldwide. Snows on Africa's Mount Kilimanjaro, extolled by Ernest Hemingway as "wide as all the world, great, high, and unbelievably white," will be gone within 14 years, Thompson estimates. Glaciers in the Alps, the Himalayas and throughout the Andes are also shrinking, he and other researchers have found.

The dramatic rise in carbon dioxide that has accompanied the industrial age has brought a spike in global temperatures. Scientists have found that the jump in temperatures is even greater in the upper atmosphere, where the glaciers reign on silent mountain peaks.

Glaciers store an estimated 70 percent of the world's fresh water. Water that falls as snow moves through the slowly churning ice and may emerge from the glacier's edge thousands of years later as meltwater. Humans have long depended on the gradual and faithful runoff.

The melting of glaciers in the Himalayas, which feed seven great Asian rivers, will bring "massive eco and environmental problems for people in western China, Nepal and northern India," a World Wildlife Fund report concluded last year.

"The repercussions of this are very scary," agreed Tim Barnett, a climate scientist with the Scripps Institution of Oceanography in San Diego. "When the glaciers are gone, they are gone. What does a place like Lima do? Or, in northwest China, there are 300 million people relying on snowmelt for water supply. There's no way to replace it until the next ice age."

At least three times a day, Eva Rondon, 38, walks the 18 worn steps carved out of the hillside of a shantytown on the far outskirts of Lima. She carries a plastic bucket to an old Shell Oil barrel with a rusty top and lid fashioned out of a few boards nailed together. She has paid a private water trucker to fill the barrel with water -- the only source for her family and neighbors -- and even that water is often dirty.

An estimated 2 million of Lima's 8 million people have no water service. Some live decades without it, buying water at as much as 30 times the price per gallon paid by customers whose homes are connected to the government-owned water utility. They are organizing to demand service from a government they say is corrupt and uncaring. But they have no doubt who will be deprived if the melting glaciers make Lima's water even scarcer.

"The poor will suffer. Our children will suffer," said Adolfo Peña, the local representative of the grass-roots political movement Peruvians Without Water. "Lima is built on a desert, and in 20 years, there's not going to be water."

If every home were connected to the utility system, there would not be enough water to pump through the pipes, said Romolo Carhuaz. He is the engineer for Sedapal, the capital's public water company, and is in charge of monitoring the reservoirs that feed Lima its water.

Each week, Carhuaz puts on a baseball cap, grabs an oxygen bottle and drives out of Lima up a jolting dirt road into the Andes mountains. He negotiates past bulls, llamas and fierce sheepdogs on his 13-hour circuit, finally grinding to a halt at a mountain plateau where cactuses bake in the cold sun. There, at 15,000 feet, lies a series of brilliant blue lagoons filled by rainwater and glacial runoff from the peaks above. Both sources, the historic lifelines for arid Lima, are now fickle, he said.

"Look at those mountains," Carhuaz said, gesturing to the rocky heights that tower over his reservoirs. White patches of snow and ice cling to some of the higher crevices. "They used to be covered with glaciers to halfway down the mountains 20 years ago."

"We call that Cat's Eye," he said, pointing out one small circle of ice left on a mountain. "It used to be huge."

Carhuaz blames the changing weather. He said average temperatures here have risen significantly in little over a decade. What used to fall as snow, adding to the glaciers, now comes as rain. And that rainfall is erratic, he said.

The changing rainfall and shrinking glaciers have also alarmed the companies that operate Peru's hydroelectric plants, which supply most of the country's electricity. "What we have seen in the past three years is a pattern that is quite different from the 40-year average," said Mark Hoffmann, the head of ElectroAndes, a private power company. "The historical data is not particularly useful in projecting anymore. We are hoping it's a blip."

Uncertain of the water supply, electric companies are building plants to generate power by using natural gas, relying on a new gas field discovered in southern Peru and government controls on prices.

"The 'wise men' believe natural gas is going to be the solution. They are clearly wrong," said Guillermo Romero, an official of Electroperu, which operates the two largest hydroelectric plants in the country. Natural gas eventually will run out, he said -- sooner rather than later if the government builds a liquefied natural gas port to export the gas. He expressed hope that the recently elected government would return its attention to building reservoirs and hydro plants.

"The problem isn't with us. It's with the government," he said.

The government has put off projects to relieve Lima's looming water deficit. Such large initiatives are expensive for a poor country, and some plans -- including the one to drill a tunnel through the Andes -- carry risks in this earthquake-prone region. In 1970, an earthquake shook loose a wall of ice and rock from the Huascaran mountain in the Andes north of Lima, burying the town of Yungay and killing tens of thousands of people.

Politicians find the scientists' broader warnings easy to ignore amid the more immediate water problems posed by burgeoning populations, increased agricultural development and contamination of water sources by mines. Some authorities acknowledge the looming crisis; others deny it.

At the local power company in Cuzco, "we are conscious that it will affect us a lot," said Mario Ortiz, a top director. But Ortiz acknowledged the company does not really know how much of its main source, the Vilcanota River, originates from glaciers. What would it mean in the dry season if the glacier is not there? Ortiz simply looks down at his desk and shakes his head.

"We're like firefighters. We only move when there is a fire," he said sadly.

The warming climate is causing other effects. In the Andes mountains north of Lima, Hugo Osoria, 32, used to work as an "ice fetcher," walking two hours from his village of Paria to cut off a chunk of glacier ice, haul it down and take a short minibus ride to the city of Huaraz to sell it. But the glaciers have retreated so much, the longer walk each way is no longer worth it. Osoria noticed changes in the local crops -- potatoes were not growing well, and worms not seen in the area before were attacking corn. So he experimented by growing flowers that were also new to village. His wife puts them in a wheelbarrow to sell them at hotels and markets in Huaraz.

"Only a few of us are trying to take advantage of the changes and make it positive," he said. For most, the climate change portends hardship.

"We are in a real critical situation," said Vincente Velasquez, 42, who grows potatoes in an area near Cuzco that the Incas called the "sacred valley" because it was so fertile. "We are talking about the melting glaciers, but we don't know what to believe. If the glaciers go away, people will think it's God's punishment."

Loayza, the 52-year-old farmer who grows fruit trees and rosemary on his land north of Cuzco, said he and his neighbors often discuss the bleak future.

"Everyone in the valley is worried about the melting ice," he said, standing in his fields, now thriving with winter sun and irrigation. "Without water, how can you work? How can you live?"

Correspondent Monte Reel in Buenos Aires, special correspondent Lucien O. Chauvin in Lima and researcher Natalia Alexandrova in Toronto contributed to this report.
0 Replies
 
sumac
 
  1  
Reply Sun 30 Jul, 2006 12:42 pm
http://www.livescience.com/forcesofnature/050330_earth_tilt.html

"Ice Ages Blamed on Tilted Earth

By Michael Schirber
LiveScience Staff Writer
posted: 30 March 2005
09:09 am ET



In the past million years, the Earth experienced a major ice age about every 100,000 years. Scientists have several theories to explain this glacial cycle, but new research suggests the primary driving force is all in how the planet leans.

The Earth's rotation axis is not perpendicular to the plane in which it orbits the Sun. It's offset by 23.5 degrees. This tilt, or obliquity, explains why we have seasons and why places above the Arctic Circle have 24-hour darkness in winter and constant sunlight in the summer.

But the angle is not constant - it is currently decreasing from a maximum of 24 degrees towards a minimum of 22.5 degrees. This variation goes in a 40,000-year cycle.

Earth's Wobble ...

... is like the precession of a spinning top.

http://www.livescience.com/images/050330_precession_03.gif

IMAGE: NASA

Peter Huybers of Woods Hole Oceanographic Institution and Carl Wunsch of the Massachusetts Institute of Technology have compared the timing of the tilt variations with that of the last seven ice ages. They found that the ends of those periods - called glacial terminations - corresponded to times of greatest tilt.

"The apparent reason for this is that the annual average sunlight in the higher latitudes is greater when the tilt is at maximum," Huybers told LiveScience in a telephone interview.

More sunlight seasonally hitting polar regions would help to melt the ice sheets. This tilt effect seems to explain why ice ages came more quickly - every 40,000 years, just like the tilt variations -- between two and one million years ago.

"Obliquity clearly was important at one point," Huybers said.

Colder planet

The researchers speculate that the glacier period has become longer in the last million years because the Earth has gotten slightly colder - the upshot being that every once in a while the planet misses a chance to thaw out.

The glacial cycles can be measured indirectly in the ratio of heavy to light oxygen in ocean sediments. Simply put, the more ice there is on Earth, the less light oxygen there is in the ocean. The oxygen ratio is recorded in the fossils of small organisms - called foraminifera, or forams for short - that make shells out of the available oxygen in the ocean.

"These ?'bugs' have been around for a long time - living all across the ocean," Huybers said. "When they die, they fall to the seafloor and become part of the sediment."

Drilled out sediment cores from the seafloor show variations with depth in the ratio of heavy to light oxygen - an indication of changes in the amount of ice over time. This record of climate change goes back tens of millions of years.

By improving the dating of these sediments, Huybers and Wunsch have showed that rapid decreases in the oxygen ratio - corresponding to an abrupt melting of ice - occurred when the Earth had its largest tilt.

Other orbital oddities

The significance of this relationship calls into question other explanations for the frequency of ice ages.

One popular theory has been that the noncircular shape, or eccentricity, of Earth's orbit around the Sun could be driving the glacial cycle, since the variations in the eccentricity have a 100,000-year period. Curiously different, but interesting.

Variation in Orbit
Period

Tilt
40,000 yr

Wobble
20,000 yr

Eccentricity
100,000 yr

By itself, though, the eccentricity is too small of an effect. According to Huybers, changes in the orbit shape cause less than a tenth of a percent difference in the amount of sunlight striking the planet.

But some scientists believe a larger effect could be generated if the eccentricity fluctuations are coupled with the precession, or wobble of the Earth's axis. It's like what is seen with a spinning top as it slows down.

Earth's axis is currently pointing at the North Star, Polaris, but it is always rotating around in a conical pattern. In about 10,000 years, it will point toward the star Vega, which will mean that winter in the Northern Hemisphere will begin in June instead of January. After 20,000 years, the axis will again point at Polaris.

Huybers said that the seasonal shift from the precession added to the eccentricity fluctuations could have an important effect on glacier melting, but he and Wunsch found that the combined model could not match the timing in the sediment data.

Skipping beats

The question, then, that Huybers and Wunsch had to answer: How does the 40,000-year tilt cycle make a 100,000-year glacial cycle? A more careful sediment dating has shown is that the time between ice ages may on average be 100,000 years, but the durations are sometimes 80,000 years, sometimes 120,000 years -- both numbers are divisible by 40,000. It appears there was not a mass melting every time the tilt reached its maximum.

"The Earth is skipping obliquity beats," Huybers explained.

The planet only recently started missing melting opportunities. Although the researchers have no corroborating evidence, they hypothesize that the skipping is due to an overall cooling of the planet.

The last major glacial thaw was 10,000 years ago, which means that the Earth is scheduled to head into another ice age. Whether human influences could reverse this, Huybers was hesitant to speculate. Other researchers have found evidence that the process of climate warming can set up conditions that create a global chill.

"What we have here is a great laboratory for seeing how climate changes naturally," he said. "But this is a 100,000-year cycle, whereas global warming is happening a thousand times faster.""
0 Replies
 
sumac
 
  1  
Reply Sun 30 Jul, 2006 12:43 pm
http://www.livescience.com/environment/060727_cosmic_dust.html

Cosmic Dust Ruled Out in Ancient Global Warming

By Sara Goudarzi
LiveScience Staff Writer
posted: 27 July 2006
02:00 pm ET



About 40,000 tons of space dust showers down on Earth each year. And it's been coming down at a steady rate for the past 30,000 years, according to a new study that suggests cosmic dust couldn't have helped end the last glacial period as some scientists have argued.

The researchers identified cosmic dust contained within an Antarctic ice core sample by measuring a form of helium that is rare on Earth. This allowed them to figure out how much and how frequently the cosmic dust came down in the last 30,000 years.

Somewhere around 120,000 years ago, temperatures started falling around the Earth and ice sheets crept downwards from the northern hemisphere. This cooling period ended around 11,000 years ago.

Some scientists argue that extraterrestrial dust particles helped end the cooling period by changing Earth's climate. One theory is that the dust helped form very high altitude clouds, which are believed to affect climate.

But the new finding suggests such ideas are unlikely, Winckler said.

"If this was true, you'd see huge changed in accreted dust," she told LiveScience. "Since we didn't see that, it argues against it."

The finding will be detailed in the July 27 issue of journal Science.
0 Replies
 
sumac
 
  1  
Reply Mon 31 Jul, 2006 10:16 am
http://www.cbsnews.com/stories/2006/07/31/tech/main1847758.shtml

"Calif., U.K. Teaming Up On Environment

WASHINGTON, July 31, 2006
--------------------------------------------------------------------------------
(AP) Britain and California are preparing to sidestep the Bush administration and fight global warming together by creating a joint market for greenhouse gases.

British Prime Minister Tony Blair and California Governor Arnold Schwarzenegger plan to lay the groundwork for a new trans-Atlantic market in carbon dioxide emissions, The Associated Press has learned. Such a move could help California cut carbon dioxide and other heat-trapping gases scientists blame for warming the planet. President Bush has rejected the idea of ordering such cuts.

Blair and Schwarzenegger are expected to announce their collaboration Monday afternoon in Los Angeles, according to documents provided by British government officials on condition of anonymity because the announcement is forthcoming.

The aim is to fix a price on carbon pollution, an unwanted byproduct of burning fossil fuels like coal, oil and gasoline. The idea is to set overall caps for carbon and reward businesses that find a profitable way to minimize their carbon emissions, thereby encouraging new, greener technologies. ....."

More article at linked site.
0 Replies
 
 

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