July 15, 2008, 9:35 PM CT

Scattered nature of Wisconsin's woodlands

If a warmer Wisconsin climate causes some northern tree species to disappear in the future, it's easy to imagine that southern species will just expand their range northward as soon as the conditions suit them.

The reality, though, may not be nearly so simple. A model developed by University of Wisconsin-Madison forest ecologists Robert Scheller and David Mladenoff suggests that while certain northern species, such as balsam fir, spruce and jack pine, are likely to decline as the state's climate warms, oaks, hickories and other southern Wisconsin trees will be slow to replace them.

Why? Not only is warming expected to outpace the speed at which southern trees can migrate northward, but barriers to dispersal - especially agricultural lands - will also likely delay their progress, says Mladenoff.

"The result is that northern forest biomass in the future - that is, the standing amount of forest - could decrease, because the trees that are there now will be experiencing less than optimal conditions," he says. "And the southern species aren't going to fill in as quickly as we'd like." He and Scheller report their findings in the current issue of Climate Research

Mladenoff explains that trees "move" into new areas by producing seeds, which are then carried over short distances by wind, birds or mammals. Under the right conditions, dispersed seeds then grow into seedlings and eventually mature trees, which produce their own seeds to start the process all over again......... Posted by: Tyler      Read more         Source

July 15, 2008, 9:29 PM CT

Future snowmelt in West twice as early as expected

As per a new study, global.

warming could lead to larger changes in snowmelt in the western United States than was previously thought, possibly increasing wildfire risk and creating new water management challenges for agriculture, ecosystems and urban populations.

Researchers, including a Purdue University professor of earth and atmospheric sciences, discovered that a critical surface temperature feedback is twice as strong as what had been projected by earlier studies.

The high-resolution climate model used by the team was better able to reproduce the complex topography of the western United States and capture details of the effect of snow cover on the climate system, as well as the historical record of runoff.

The findings will be published in an upcoming issue of Geophysical Research Letters and are now available online at the journal's Web site.

Noah Diffenbaugh, senior author of the paper and an associate professor of earth and atmospheric sciences at Purdue, said the influence of melting snow on regional climate is far greater than that of increased greenhouse gases alone.

"The heat trapping from elevated greenhouse gases triggers the warming, but the additional warming caused by the loss of snow is what really creates the big changes in surface runoff," said Diffenbaugh, who also is a member of Purdue's Climate Change Research Center. "Researchers have known about this general effect for years. The big surprise here is how much the complex topography plays a role, essentially doubling the threat to water resources in the West"......... Posted by: Tyler      Read more         Source

July 14, 2008, 5:12 PM CT

Potential Effects Of Volcanic Eruptions

For the first time, scientists have taken a detailed look at what lies beneath all of Iceland's volcanoes - and found a world far more complex than they ever imagined.

They mapped an elaborate maze of magma chambers - work that could one day help researchers better understand how earthquakes and volcanic eruptions occur in Iceland and elsewhere in the world.

Knowing where magma chambers are located is a key first step to understanding the chemical composition of the molten rock that is flowing within them - and of the gases that are released when a volcano erupts, explained Daniel Kelley, doctoral student in earth sciences at Ohio State University.

Kelley and Michael Barton, professor of earth sciences at Ohio State, have determined that the volcanoes in Iceland are likely to have explosive eruptions that shoot debris far into the atmosphere. That's because the magma moves very quickly to the surface from deep within the magma chambers. Fast-moving magma propels sulfur and ash out of a volcano and high into the atmosphere, where it can spread around the planet.

"One of the reasons we're trying to understand these volcanoes is to determine exactly what the chances are of a large eruption there. We know that a large eruption in Iceland would not only have devastating local effects, but potential global effects as well - by affecting the climate," Barton said......... Posted by: Tyler      Read more         Source

July 14, 2008, 5:00 PM CT

China can't fully fix air quality problem for Olympics

The outlook for air quality in Beijing during the Olympics is borderline, and there's little that the Chinese government can do to improve it. That's the conclusion drawn by a University of Rhode Island atmospheric chemist who analyzed pollution data collected regularly for the last five years by Chinese scientists.

"There is both a local component and a regional component to the pollutants that cause unhealthy air in Beijing, and the severity of their effects are driven by weather fronts and winds," said Kenneth Rahn, a retired URI professor who travels to China several times a year to help researchers at Tsinghua University interpret their data. "Since it's controlled by the weather, it will be a matter of luck whether the bad air periods correspond with days of outdoor Olympic events".

Locally generated pollutants in Beijing consist primarily of organic matter from transportation, factories and cooking, while regional sources of pollution include ammonium sulfates and ammonium nitrates from coal-burning power plants, industry and transportation sources, which are easily transported long distances in the atmosphere, as per Rahn.

"The air pollution pattern in Beijing is unusual, with high and low concentrations that can differ by a factor of 50 to 100," Rahn said. "When the winds shift to the north and bring in clear air from Mongolia, the air can be relatively clean, though that's not the norm during the summer. But when winds are from the south, where there is a large population and lots of industrial activity, the air can be especially hazardous"......... Posted by: Tyler      Read more         Source

July 14, 2008, 4:42 PM CT

Physicists tweak quantum force

Cymbals don't clash of their own accord - in our world, anyway.

But the quantum world is bizarrely different. Two metal plates, placed almost infinitesimally close together, spontaneously attract each other.

What seems like magic is known as the Casimir force, and it has been well-documented in experiments. The cause goes to the heart of quantum physics: Seemingly empty space is not actually empty but contains virtual particles linked to fluctuating electromagnetic fields. These particles push the plates from both the inside and the outside. However, only virtual particles of shorter wavelengths - in the quantum world, particles exist simultaneously as waves - can fit into the space between the plates, so that the outward pressure is slightly smaller than the inward pressure. The result is the plates are forced together.

Now, University of Florida physicists have found they can reduce the Casimir force by altering the surface of the plates. The discovery could prove useful as tiny "microelectromechanical" systems - so-called MEMS devices that are already used in a wide array of consumer products - become so small they are affected by quantum forces.

"We are not talking about an immediate application," says Ho Bun Chan, an assistant professor of physics and the first author of a paper on the findings that appears today in the online edition of the journal Physical Review Letters......... Posted by: Kevin      Read more         Source

July 10, 2008, 9:27 PM CT

Wilkins Ice Shelf hanging by its last thread

The Wilkins Ice Shelf is experiencing further disintegration that is threatening the collapse of the ice bridge connecting the shelf to Charcot Island. Since the connection to the island in the image centre helps to stabilise the ice shelf, it is likely the break-up of the bridge will put the remainder of the ice shelf at risk.

This animation, comprised of images acquired by Envisat's Advanced Synthetic Aperture Radar (ASAR) between 30 May and 9 July 2008, shows the break-up event which began on the east (right) rather than the on west (left) like the prior event that occurred last month. By 8 July, a fracture that could open the ice bridge was visible.

As per the image acquired on 7 July 2008, Dr Matthias Braun from the Center for Remote Sensing of Land Surfaces at Bonn University estimates the area lost on the Wilkins Ice Shelf during this break-up event is about 1350 km² with a rough estimate of 500 to 700 km² in addition being lost if the bridge to Charcot Island collapses.

This break-up is puzzling to researchers because it has occurred in the Southern Hemispheric winter and does not have characteristics similar to two earlier events that occurred in 2008, which were comparable to the break-up of the Larsen-A and -B ice shelves.

"The scale of rifting in the newly-removed areas seems larger, and the pieces are moving out as large bergs and not toppled, finely-divided ice melange," said Ted Scambos from the National Snow and Ice Data Center who uses ASAR images to track the area......... Posted by: Tyler      Read more         Source

July 10, 2008, 8:45 PM CT

Fossil Feathers Preserve Evidence of Color

Traces of organic material found in fossil feathers are remnants of pigments that once gave birds their color, as per researchers whose research results are published online this week in the journal Biology Letters.

Their findings open the potential to depict the original coloration of fossilized birds and their ancestors, the dinosaurs.

"These results may lead to predicting feather color in ancient birds and related species," said H. Richard Lane, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "Through this understanding, we may be able to learn about their ecology and behavior".

Closer study of many fossilized bird feathers by scientist Jakob Vinther of Yale University in New Haven, Conn., revealed that organic imprints in fossils--previously believed to be carbon traces from bacteria--are fossilized melanosomes, the organelles that contain melanin pigment.

"Birds have spectacularly colored plumage often used in camouflage and courtship display," said Vinther. "Feather melanin is responsible for rusty-red to jet-black colors, and produces glossy iridescence.

"That melanin can resist decay for millions of years".

Working with Yale paleontologist Derek Briggs and Yale ornithologist Richard Prum, Vinther analyzed a striped feather found in 100 million-year-old rocks in Brazil......... Posted by: William      Read more         Source

July 10, 2008, 8:38 PM CT

Long Wait Before Next China Quake?

A new analysis of the setting for May's devastating earthquake in China shows that the quake resulted from faults with little seismic activity--and that similar events in that area occur, on average, only once every 2,000 to 10,000 years. However, geologists caution that because earthquakes can sometimes occur in clusters, people should still be wary of another possible large-scale earthquake.

Clark Burchfiel and Leigh Royden, geologists at MIT, have done extensive research in China for more than two decades but had found no hints that suggested such a large earthquake might strike the area.

They and his colleagues, including MIT's Robert van der Hilst and Bradford Hager, have published a paper analyzing the causes of the quake in the recent issue of the journal GSA Today.

"This is an excellent example of how long-term support of basic research can provide valuable insights into the cause of a major natural disaster," says Leonard Johnson, program director in the National Science Foundation's Division of Earth Sciences, which funded the research.

The magnitude 7.9 quake struck Sichuan province on May 12, 2008, at around noon, which may have increased the human death toll because a number of children were at school. The school buildings turned out to be particularly vulnerable to collapse because of poor construction......... Posted by: Tyler      Read more         Source

July 10, 2008, 8:28 PM CT

Methane Formation in the Oceans

A new pathway for methane formation in the oceans has been discovered, with significant potential for advancing our understanding of greenhouse gas production on Earth, researchers believe.

A paper on the findings, reported in the July 2008, issue of the journal Nature Geoscience, reveals that decomposition of a phosphorus-containing compound called methylphosphonate may be responsible for an unexpected supersaturation of methane in the oceans' oxygen-rich surface waters.

Through the National Science Foundation (NSF) Center for Microbial Oceanography: Research and Education (C-MORE), oceanographer David Karl of the University of Hawaii and microbiologist Edward DeLong of the Massachusetts Institute of Technology, co-authors of the Nature Geoscience paper, are working to learn how and when microbes turn on and off their methane production genes in response to methane precursors like methylphosphonate.

"This newly recognized pathway of methane formation needs to be incorporated into our thinking about global climate change," says Karl.

Methane is a more potent greenhouse gas than carbon dioxide on a per weight basis. Eventhough the volume of methane in the atmosphere is less than carbon dioxide, methane is much more efficient at trapping the long wavelength radiation that keeps our planet habitable. It's also responsible, therefore, for increased greenhouse warming......... Posted by: Tyler      Read more         Source

July 10, 2008, 8:26 PM CT

A Colorful Approach to Solar Energy

Revisiting a once-abandoned technique, engineers at the Massachusetts Institute of Technology (MIT) have successfully created a sophisticated, yet affordable, method to turn ordinary glass into a high-tech solar concentrator.

The technology, which uses dye-coated glass to collect and channel photons otherwise lost from a solar panel's surface, could eventually enable an office building to draw energy from its tinted windows as well as its roof.

Electrical engineer Marc Baldo, his graduate students Michael Currie, Jon Mapel and Timothy Heidel, and postdoctoral associate Shalom Goffri, announced their findings in the July 11 issue of Science.

"We think this is a practical technology for reducing the cost of solar power," said Baldo.

The scientists coated glass panels with layers of two or more light-capturing dyes. The dyes absorbed incoming light and then re-emitted the energy into the glass, which served as a conduit to channel the light to solar cells along the panels' edges. The dyes can vary from bright colors to chemicals that are mostly transparent to visible light.

Because the edges of the glass panels are so thin, far less semiconductor material is needed to collect the light energy and convert that energy into electricity......... Posted by: Kevin      Read more         Source