January 24, 2008, 11:12 PM CT

Sheds light on ocean current dynamics

Ocean surface currents have long been the focus of research due to the role they play in weather, climate and transportation of pollutants, yet essential aspects of these currents remain unknown.

By employing a new technique - based on the same principle as police speed-measuring radar guns - to satellite radar data, researchers can now obtain information necessary to understand better the strength and variability of surface current regimes and their relevance for climate change.

Researchers at the SeaSAR 2008 workshop held this week in ESRIN, ESA's European Centre for Earth Observation in Frascati, Italy, demonstrated how this new method on data from the Advanced Synthetic Aperture Radar (ASAR) instrument aboard ESA's Envisat, enabled measurements of the speed of the moving ocean surface.

Synthetic Aperture Radar (SAR) instruments, such as ASAR, record microwave radar backscatter in order to identify roughness patterns, which are associated with varying surface winds, waves and currents of the ocean surface. However, interpreting radar images to identify and quantify surface currents had proven very difficult.

By using the new information embedded in the radar signal - the Doppler shift of the electromagnetic waves reflected from the water surface - Dr Bertrand Chapron of the French Research Institute for Exploitation of the Sea (IFREMER), Dr Johnny Johannessen of Norway's Nansen Environmental and Remote Sensing Centre (NERSC) and Dr Fabrice Collard of France's BOOST Technologies were able to determine how surface winds and currents contribute to the Doppler shift......... Posted by: Tyler      Read more         Source

January 24, 2008, 11:08 PM CT

Climate change poses a huge threat to human health

Climate change will have a huge impact on human health and bold environmental policy decisions are needed now to protect the worlds population, as per the author of an article reported in the BMJ today.

The threat to human health is of a more fundamental kind than is the threat to the worlds economic system, says Professor McMichael, a Professor of public health from the Australian National University. Climate change is beginning to damage our natural life-support system, he says.

The risks to health are a number of, and include the impact of heat waves, floods and wildfires, changes in infectious disease patterns, the effect of worsening food yields and loss of livelihoods.

The World Health Organisation estimates that a quarter of the worlds disease burden is due to the contamination of air, water, soil and food especially from respiratory infections and diarrhoeal disease.

Climate change, says Professor McMichael, will make these and other diseases worse. While it is unlikely to cause entirely new diseases it will alter the incidence, range and seasonality of a number of existing health disorders. So, for example, by 2080 between 20 and 70 million more people could be living in malarial regions due to climate change.

The adverse health impacts will be much greater in low-income countries and vulnerable sub-populations than in richer nations......... Posted by: Tyler      Read more         Source

January 24, 2008, 11:00 PM CT

When accounting for the global nitrogen budget, don't forget fish

Like bank accounts, the nutrient cycles that influence the natural world are regulated by inputs and outputs. If a routine withdrawal is overlooked, balance sheets become inaccurate. Over time, overlooked deductions can undermine our ability to understand and manage ecological systems.

Recent research by the Universite de Montreal (Canada) and the Cary Institute of Ecosystem Studies (Millbrook, New York) has revealed an important, but seldom accounted for, withdrawal in the global nitrogen cycle: commercial fisheries. Results, published as the cover story in the recent issue of Nature Geoscience, highlight the role that fisheries play in removing nitrogen from coastal oceans.

Nitrogen is essential to plant and animal life; however, it is possible to have too much of a good thing. During the past century, a range of human activities have increased nitrogen inputs to coastal waters. Fertilizer run-off is the best documented and most significant source of terrestrial nitrogen pollution. Nitrogen-rich fertilizer applied to farmland eventually makes its way into coastal waters via a network of streams and rivers.

Research spearheaded by Roxane Maranger (Universite de Montreal) and Nina Caraco (Cary Institute) demonstrates that commercial fisheries play an important but declining role in removing terrestrial nitrogen from coastal waters. Accounting for this withdrawal is crucial; terrestrial-derived nitrogen can stimulate coastal phytoplankton growth, leading to eutrophication. Typically typically eutrophic waters are characterized by reduced dissolved oxygen, decreased biodiversity, and species composition shifts......... Posted by: Tyler      Read more         Source

January 21, 2008, 9:22 PM CT

First evidence of under-ice volcanic eruption

The first evidence of a volcanic eruption from beneath Antarcticas most rapidly changing ice sheet is reported this week in the journal Nature Geosciences. The volcano on the West Antarctic Ice Sheet erupted 2000 years ago (325BC) and remains active.

Using airborne ice-sounding radar, researchers from British Antarctic Survey (BAS) discovered a layer of ash produced by a subglacial volcano. It extends across an area larger than Wales.

Lead author, Hugh Corr of the BAS says,.

The discovery of a subglacial volcanic eruption from beneath the Antarctic ice sheet is unique in itself. But our techniques also allow us to put a date on the eruption, determine how powerful it was and map out the area where ash fell. We believe this was the biggest eruption in Antarctica during the last 10,000 years. It blew a substantial hole in the ice sheet, and generated a plume of ash and gas that rose around 12 km into air.

The discovery is another vital piece of evidence that will help determine the future of the West Antarctic Ice Sheet and refine predictions of future sea-level rise. Co-author Professor David Vaughan (BAS) says,.

This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet. The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters......... Posted by: Tyler      Read more         Source

January 17, 2008, 9:09 PM CT

Winter Ice on Lakes: A Thing of the Past?

If you're planning to ice skate on a local lake or river this winter, you may need to think twice, as per researchers John Magnuson, Olaf Jensen and Barbara Benson of the University of Wisconsin at Madison. Their research is funded by the National Science Foundation (NSF).

From sources as diverse as newspaper archives, transportation ledgers and religious observances, the scientists have amassed 150 years of lake and river ice records spanning the Northern Hemisphere. All show a steady trend of fewer days of ice cover.

If the pattern continues, only in Currier and Ives prints will ice skaters twirl across frozen rivers.

The records show that later freezing and earlier ice breakup occurred on lakes and rivers across the Northern Hemisphere from 1846 to 1995. Over those 150 years, said Magnuson, changes in freeze dates averaged 5.8 days per 100 years later, and changes in ice breakup dates averaged 6.5 days per 100 years earlier. The findings translate to increasing air temperatures of about 1.2 degrees Celsius each century.

Now the researchers have looked more specifically at trends in ice duration in 65 waterbodies across what might be called the last bastion of winter in the U.S.--the Great Lakes region (Minnesota, Wisconsin, Michigan, Ontario and New York)--during a period of rapid climate warming (1975-2004)......... Posted by: Tyler      Read more         Source

January 17, 2008, 9:00 PM CT

Quakes Under Pacific Ocean Floor

Zigzagging some 60,000 kilometers across the ocean floor, Earth's system of mid-ocean ridges plays a pivotal role in a number of workings of the planet: in plate-tectonic movements, heat flow from the interior, and the chemistry of rock, water and air.

Now, a team of seismologists working in 2,500 meters of water on the East Pacific Rise, some 565 miles southwest of Acapulco, Mexico, has made the first images of one of these systems--and it doesn't look the way most researchers had assumed. The research results, funded by the National Science Foundation (NSF), appear in this week's issue of the journal Nature.

It was not until the late 1970s that researchers discovered the existence of vast plumbing systems under the oceans called hydrothermal vents. The systems pull in cold water, superheat it, then spit it back out from seafloor vents--a process that brings up not only hot water, but dissolved substances from rocks below. Unique life forms feed off the vents' stew, and valuable minerals including gold may pile up.

The hypothetical image of a hydrothermal-vent system shows water forced down by overlying pressure through large faults along ridge flanks. The water is heated by shallow volcanism, then rises toward the ridges' middles, where vents (often called "black smokers," for the cloud of chemicals they exude) tend to cluster......... Posted by: Tyler      Read more         Source

January 14, 2008, 3:24 PM CT

Effects of global change on Mackenzie River Delta

River delta regions along the Arctic coast are poorly understood ecosystems that are expected to change rapidly as the climate warms, sea levels rise, and seasonal river ice jams become less frequent. In northern Canada's Mackenzie River Delta, flood pulses driven by ice breakup control the degree to which river water moves off-channel to replenish nearby lakes, which only exist because of such river dynamics.

Lesack and Marsh analyze more than 30 years of data on the Mackenzie Delta and find that the duration of river-to-lake connection has lengthened on average more than 30 days since the 1970s. Further, the duration of river-to-lake connection has shortened in the highest elevation lakes, likely owing to the declining effects of river-ice breakup. The authors conclude that not only are the higher elevation lakes at risk of drying up from declining water level peaks, but lower elevation lakes now contain more water than can be accounted for through sea level rise, suggesting that increasing storm surge intensity, permafrost melting, or backwater flow might play an unexpected role......... Posted by: Tyler      Read more         Source

January 10, 2008, 10:58 PM CT

A warming climate can support glacial ice

New research challenges the generally accepted belief that substantial ice sheets could not have existed on Earth during past super-warm climate events. The study by scientists at Scripps Institution of Oceanography at UC San Diego provides good evidence that a glacial ice cap, about half the size of the modern day glacial ice sheet, existed 91 million years ago during a period of intense global warming. This study offers valuable insight into current day climate conditions and the environmental mechanisms for global sea level rise.

The new study in the Jan. 11 issue of the journal Science titled, Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse, examines geochemical and sea level data retrieved from marine microfossils deposited on the ocean floor 91 million years ago during the Cretaceous Thermal Maximum. This extreme warming event in Earths history raised tropical ocean temperatures to 35-37C (95-98.6F), about 10C (50F) warmer than today, thus creating an intense greenhouse climate.

Using two independent isotopic techniques, scientists at Scripps Oceanography studied the microfossils to gather geochemical data on the growth and eventual melting of large Cretaceous ice sheets. The scientists compared stable isotopes of oxygen molecules (d18O) in bottom-dwelling and near-surface marine microfossils, known as foraminifera, to show that changes in ocean chemistry were consistent with the growth of an ice sheet. The second method in which an ocean surface temperature record was subtracted from the stable isotope record of surface ocean microfossils yielded the same conclusion......... Posted by: Tyler      Read more         Source

January 10, 2008, 10:50 PM CT

Fighting pollution the poplar way

Purdue University scientists are collaborating with Chrysler LLC in a project to use poplar trees to eliminate pollutants from a contaminated site in north-central Indiana.

The scientists plan to plant transgenic poplars at the site, a former oil storage facility near Kokomo, Ind., this summer. In a laboratory setting, the transgenic trees have been shown to be capable of absorbing trichloroethylene, or TCE, and other pollutants before processing them into harmless byproducts.

Richard Meilan, a Purdue associate professor, is currently at work to transform one variety of poplar suited to Indiana's climate; cold-hardy poplars are generally more difficult to alter than the variety used in a laboratory setting.

"This site presents the perfect opportunity to prove that poplars can get rid of pollution in the real world," Meilan said.

In a study Meilan co-authored, published last October in Proceedings of the National Academy of Sciences, poplar cuttings removed 90 percent of the TCE within a hydroponic solution in one week. The engineered trees also took up and metabolized the chemical 100 times faster than unaltered hybrid poplars, which have a limited ability to remove and degrade the contaminant on their own, he said.

The transgenic poplars contain an inserted gene that encodes an enzyme capable of breaking down TCE and a variety of other environmental pollutants, including chloroform, benzene, vinyl chloride and carbon tetrachloride......... Posted by: Tyler      Read more         Source

January 8, 2008, 8:25 PM CT

Hope Diamond's fiery red glow

A study released in the January 2008 edition of the journal Geology proves that a blue diamonds rare appeal goes far beyond its beauty. The study was conducted by Jeffrey Post, curator of the National Gem Collection and mineralogist, at the Smithsonians National Museum of Natural History. Post and six other scientists probed the mysterious phosphorescence of the Hope Diamond and other natural blue diamonds and discovered a way to fingerprint individual blue diamonds.

The 45.52-carat blue Hope Diamond is the centerpiece of the National Gem Collection on display at the National Museum of Natural History and it attracts the attention of millions of visitors each year. One aspect of this famous diamond that most people do not get to see is its fiery red phosphorescence that results from exposure to ultraviolet light, which continues for more than a minute. The mysterious red phosphorescence, rarely seen in other blue diamonds, added to the Hope Diamonds mystique and allure. However, the mystery has now been solved.

Scientists at the Smithsonian and the U.S. Naval Research Laboratory measured the phosphorescence spectra of the Hope Diamond and 66 other natural blue diamonds, including the 30.82-carat Blue Heart Diamond in the Smithsonians National Gem Collection......... Posted by: Tyler      Read more         Source