July 5, 2007, 9:41 PM CT

The Earth is smaller than assumed

Eventhough the discrepancy is not large, it is significant: Geodesists from the University of Bonn have remeasured the size of the Earth in a long lasting international cooperation project. The blue planet is accordingly some millimeters smaller than up to now assumed. The results are important, for example, to be able to demonstrate a climate contingent rise in sea level. The results have now appeared in the renowned Journal of Geodesy.

The system of measurement used by the Bonn Geodesists is invisible. It consists of radiowaves that are transmitted into space from punctiform sources, the so-called Quasars. A network of more than 70 radio telescopes worldwide receives these waves. Because the gaging stations are so far apart from each other, the radio signals are received with a slight time-lag. From this difference we can measure the distance betwen the radio telescopesand to the preciseness of two millimeters per 1,000 kilometers, explained Dr. Axel Nothnagel, reasearch group leader for the Geodesy Institute of the University of Bonn.

The procedure is called VLBI, which stands for Very Long Baseline Interferometry. The technique can be used, for example, to demonstrate that Europe and North America are distancing from each other at a rate of about 18 millimeters annually. The distance of the gaging stations from each other allows the the size of the Earth or the exact location of the center of the Earth to be determined. We have analyzed the measurements and calculations from 34 partners in 17 countries, explained Nothnagel. A combination of GPS and satellite laser measurements will enable the availability of the coordinates from almost 400 points on the surface of the Earth with unparalleled exactness......... Posted by: Tyler      Read more         Source

July 4, 2007, 5:07 AM CT

Urban Growth And Changing Rainfall Patterns

For the first time, researchers have used satellite images to demonstrate a link between rapid city growth and rainfall patterns, as well as to assess compliance with an international treaty to protect wetlands. The results have been published in two studies co-authored by Karen Seto, assistant professor of geological and environmental sciences and a fellow at the Woods Institute for the Environment at Stanford University.

''The exciting thing is really for the first time, using a time series of satellite images, we can monitor Earth in a way that we haven't been able to,'' Seto said. ''It's not just about urban growth or wetlands-it could be about desertification or deforestation-but it's really just this issue of human modification of the Earth.''.

In one study, reported in the July online issue of the journal Global Environmental Change, Seto and her colleagues showed that inclusion in an international environmental agreement did not significantly improve the health of a coastal mangrove habitat in a wetland preserve in Vietnam. In the second study, published May 15 in the Journal of Climate, the scientists observed that rapid urban growth has caused drier winters in the Pearl River Delta of China.

Both findings are based on an analysis of satellite images of Vietnam and China, which NASA has been collecting through its Land Remote-Sensing Satellite (Landsat) Program for more than 30 years......... Posted by: Tyler      Read more         Source

June 27, 2007, 6:20 PM CT

Ready for NASA climate change, ozone mission in tropics

A high-flying NASA mission over Costa Rica and Panama in July and August should help researchers better understand how tropical storms influence global warming and stratospheric ozone depletion, says a University of Colorado at Boulder professor who is one of two mission researchers for the massive field campaign.

Brian Toon, chair of CU-Boulder's atmospheric and oceanic sciences department, said the $12 million effort will mobilize in San Jose, Costa Rica, and involve about 400 scientists, students and support staff operating three NASA aircraft, seven satellites and a suite of other instruments. The team is targeting the gases and particles that flow out of the top of the vigorous storm systems that form over the warm tropical ocean, said Toon.

The warm summer waters of the Pacific Ocean in Central and South America are a breeding ground for heat-driven convective storms targeted by the mission, said NASA officials. Such tropical systems are the major mechanism for Earth's system to loft air into the upper troposphere and stratosphere and are characterized primarily by cumulus clouds with large dense anvils and wispy cirrus clouds.

Known as the Tropical Composition, Cloud and Climate Coupling mission, or TC4, The expedition runs from July 16 through Aug. 8 and is NASA's largest field campaign in several years. The tropical storm systems under study pump air more than 40,000 feet above the surface, where they can influence the make-up of the stratosphere, home of Earth's protective ozone layer......... Posted by: Tyler      Read more         Source

June 27, 2007, 5:42 PM CT

Northern Forests Less Effective in Reducing Global Warming

Forests in the United States and other northern mid- and upper-latitude regions are playing a smaller role in offsetting global warming than previously thought, as per a research studyappearing in this week's issue of Science.

The study, which sheds light on the so-called missing carbon sink, concludes that intact tropical forests are removing an unexpectedly high proportion of carbon dioxide from the atmosphere, thereby partially offsetting carbon entering the air through industrial emissions and deforestation.

The Science paper was written by a team of researchers led by Britton Stephens of the National Center for Atmospheric Research (NCAR) in Boulder, Colo. The research was funded by the National Science Foundation (NSF).

"This research fills in another piece of the complex puzzle on how the Earth system functions," said Cliff Jacobs of NSF's Division of Atmospheric Sciences. "These findings will be viewed as a milestone in discoveries about our planet's 'metabolism.'".

Stephens and colleagues analyzed air samples that had been collected by aircraft across the globe for decades but never before synthesized to study the global carbon cycle. The team observed that some 40 percent of the carbon dioxide assumed to be absorbed by northern forests is instead being taken up in the tropics......... Posted by: Tyler      Read more         Source

June 25, 2007, 7:53 PM CT

Desert Droughts Lead To Earlier Annual Mountain Snow Loss

A new study spearheaded by the University of Colorado at Boulders National Snow and Ice Data Center indicates wind-blown dust from drought-stricken and disturbed lands in the Southwest can shorten the duration of mountain snow cover hundreds of miles away in the Colorado mountains by roughly a month.

Led by Tom Painter, the study found seasonal snow coverage in the sub-alpine and alpine areas of the San Juan Mountains of southwestern Colorado disappeared by about 30 days earlier in 2006 because of heavy dust deposition from the Colorado Plateau roughly 200 miles away. The dust, which probably came from northeast Arizona and northwest New Mexico deserts, reduced the snows reflectivity, allowing more of the suns energy to warm the snow pack and cause it to melt earlier.

The correlation between dust and lower snow reflectance is already established, but the amount of impact measured and modeled in this system stunned us, said Painter. The fact that dust can reduce snow cover duration so much a month earlier -- transforms our understanding of mountain sensitivity to external forcings.

While just three or four significant dust deposition events occurred annually in the San Juan Mountains between 2003 and 2005, eight occurred in 2006, as per the authors. In 2006, the sub-alpine regions of the San Juans melted out 24 to 35 days earlier than previous, relatively dust-free years, as per ground measurements and computer simulations......... Posted by: Tyler      Read more         Source

June 20, 2007, 10:04 AM CT

Certain Home Shapes And Roofs Hold Up Best In Hurricane

Certain home shapes and roof types can better resist high winds and hurricanes, as per a researcher at New Jersey Institute of Technology (NJIT). Civil engineer Rima Taher, PhD, special lecturer in the New Jersey School of Architecture at NJIT, spent two years examining the findings of research centers that have studied the best designs and construction materials and methods needed to withstand extreme wind events and hurricanes.

Eventhough Id like to say that there is a simple and economical solution for housing that wont fail or collapse in the perfect storm, such information does still not exist, said Taher. However, it is obvious that thanks to the work of wind engineers and scientists that changes to home design and construction can make buildings safer for people, while saving government and industry billions of dollars annually.

Design of Low-Rise Buildings for Extreme Wind Events (Journal of Architectural Engineering, March, 2007) by Taher highlighted such research findings. Wind scientists at the Center for Building Science and Technology (CSTB) in France, researched and tested reduced-scale home models at its wind tunnel facilities, and developed a prototype of a cyclonic or hurricane-resistant dwelling. Taher cooperated with the CSTB wind researchers, working on the structural aspect of the homes design......... Posted by: Tyler      Read more         Source

June 20, 2007, 9:55 AM CT

Giant magnetocaloric materials for the environment

Materials that change temperature in magnetic fields could lead to new refrigeration technologies that reduce the use of greenhouse gases, thanks to new research at the U.S. Department of Energy's Argonne National Laboratory and Ames National Laboratory.

Researchers carrying out X-ray experimentation at the Advanced Photon Source at Argonne - the nation's most powerful source of X-rays for research - are learning new information about magnetocaloric materials that have potential for environmentally friendly magnetic refrigeration systems.

Magnetic refrigeration is a clean technology that uses magnetic fields to manipulate the degree of ordering (or entropy) of electronic or nuclear magnetic dipoles in order to reduce a material's temperature and allow the material to serve as a refrigerant. New materials for refrigeration based on gadolinium-germanium-silicon alloys display a giant magnetocaloric effect due to unusual coupling between the material's magnetism and chemical structure.

Understanding this coupling is essential to moving this technology from the laboratory to the household. Magnetic refrigeration does not rely on hydrofluorocarbons (HFCs) used in conventional refrigeration systems. HFCs are greenhouse gases that contribute to global climate change when they escape into the atmosphere......... Posted by: Kevin      Read more         Source

June 20, 2007, 9:44 AM CT

How do Americans want to reduce greenhouse gas emissions?

Most Americans now think that global warming is happening, and they want the federal government to take action to limit its effects. But what form should that action take" And does support for action hold firm if people understand how much it may cost them financially" .

To find out, New Scientist, Stanford University and Resources for the Future, an independent think tank, commissioned the survey research firm Knowledge Networks to query a representative sample of American adults.

We investigated three main ways of reducing greenhouse pollution.

1)Standards or mandates: The government tells companies exactly how they must generate electricity or manufacture vehicle fuel to achieve a cut in emissions.

2) Emissions Tax: The government taxes companies for their greenhouse gas emissions.

3) Cap-and-Trade: The government imposes a cap on companies greenhouse gas emissions, but allows companies to trade permits - which represent the right to emit a certain amount of pollution.

The aim of our poll was to test the relative attractiveness of these three options. We told 1,491 adults how each option could work in each of two sectors: vehicle fuel and electricity. We chose these sectors because they are each responsible for a substantial proportion of US greenhouse emissions, and because any costs of making cuts will likely be passed onto consumers. That gave a total of six possible policies, each of which we told respondents would reduce total projected US greenhouse emissions in 2020 by five percent......... Posted by: Tyler      Read more         Source

June 20, 2007, 8:12 AM CT

The woes of Kilimanjaro

The "snows" of Africa's Mount Kilimanjaro inspired the title of an iconic American short story, but now its dwindling icecap is being cited as proof for human-induced global warming.

However, two scientists writing in the July-August edition of American Scientist magazine say global warming has nothing to do with the decline of Kilimanjaro's ice, and using the mountain in northern Tanzania as a "poster child" for climate change is simply inaccurate.

"There are dozens, if not hundreds, of photos of midlatitude glaciers you could show where there is absolutely no question that they are declining in response to the warming atmosphere," said climatologist Philip Mote, a University of Washington research scientist.

But in the tropics -- especially on Kilimanjaro -- processes are at work that are far different from those that have diminished glacial ice in temperate regions closer to the poles, he said.

Mote and Georg Kaser, a glaciologist at the University of Innsbruck in Austria, write in American Scientist that the decline in Kilimanjaro's ice has been going on for more than a century and that most of it occurred before 1953, while evidence of atmospheric warming there before 1970 is inconclusive.

They attribute the ice decline primarily to complex interacting factors, including the vertical shape of the ice's edge, which allows it to shrink but not expand. They also cite decreased snowfall, which reduces ice buildup and determines how much energy the ice absorbs -- because the whiteness of new snow reflects more sunlight, the lack of new snow allows the ice to absorb more of the sun's energy......... Posted by: Tyler      Read more         Source

June 18, 2007, 10:05 PM CT

Stealth Tsunami That Killed 600 In Java Last Summer

Though categorized as magnitude 7.8, the earthquake could scarcely be felt by beachgoers that afternoon. A low tide and wind-driven waves disguised the signs of receding water, so when the tsunami struck, it caught even lifeguards by surprise. That contributed to the death toll of more than 600 persons in Java, Indonesia.

The general assumption was that if you were near the coast where the earthquake took place, you would feel it and be able to run to higher ground, said Hermann Fritz, first author of a new Geophysical Research Letters paper about the July 17, 2006 tsunami. This event caught people by surprise and showed that its not always that simple.

The earthquake was slow rupturing, so it didnt produce strong ground shaking on Java that might have alerted people on the beach, he explained.

No local warning was issued for the tsunami waves, which arrived only tens of minutes after the earthquake. Fortunately, the event took place on a Monday. Had the massive waves hit the day before, which was a major national holiday, the popular beach would have been much more crowded and the toll higher.

Warning systems typically dont work very well for locations near earthquakes, where there are only tens of minutes between the earthquake and the tsunamis arrival, noted Fritz, a Georgia Institute of Technology assistant professor who led an inspection team to Java a week after the event. Its pretty much a spontaneous self-evacuation. You normally feel the earthquake or see the ocean withdraw. If you hear the noise in the last tens of seconds before it hits, then its just a matter of who makes it and who doesnt......... Posted by: Tyler      Read more         Source