August 1, 2006, 11:37 PM CT

Threats To Planet's Life

In a report released recently, researchers call for a new systematic study of the Earth's "critical zone"--the life-sustaining outermost surface of the planet, from the vegetation canopy to groundwater and everything in between.Understanding and predicting responses to global and regional change is necessary, they say, to mitigate the impacts of humans on complex ecosystems and ultimately sustain food production.

"Development is having a great effect on the critical zone," said soil scientist Donald Sparks of the University of Delaware and co-chair of the NSF workshop that led to the report, entitled Frontiers in Exploration of the Critical Zone. "Converting some of the best land around the world into buildings, roads and concrete has implications for air and water quality and biodiversity, and over time could put pressure on our ability to produce food.

Critical zone sites include an extraordinary diversity of soils and ecosystems ranging from the tropics to the poles, from deserts to wetlands, and from rock-bound uplands to delta sediments.

"Because the critical zone includes air, water and soil and is the focal point of food production, it has a major effect on human life," Sparks said. "It is imperative that we better understand the interactions that occur there".........

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August 1, 2006, 11:18 PM CT

At An Underwater Volcano

Researchers studying hydrothermal vents, those underwater geysers that are home to bizarre geological structures and unique marine species, have discovered something all too familiar: pollution.

A University of Florida geologist is among a team of geologists that is the first to observe "anthropogenic influence" in hydrothermal deposits, as per an article in the recent issue of the journal Marine Geology. Examining deposits retrieved from the site of an underwater volcano near Italy, they discovered lead that did not come from the underlying rocks or from any possible natural source in the nearby region or anywhere in Europe.

Instead, they traced the lead to an Australian lead mine thousands of miles away.

"I guess we can speculate that this is yet another piece of evidence of how widespread our disturbance in the environment is: the fact that we can influence natural hydrothermal systems," said George Kamenov, a faculty member at the UF geological sciences department.

Hydrothermal vents form when seawater seeps through cracks in the deep ocean floor, gets heated by magma, or molten rock, then streams upward back into the sea. The vents have aroused a great deal of scientific interest since they were discovered in 1977, in part because of their remarkable appearance but mainly because they host unusual creatures and offer natural laboratories to study the formation of metal ores. Some have tall and elaborate "chimneys" formed from minerals disbursed by the hot water as it leaves the ocean floor. "Black smokers," the hottest hydrothermal vents, spew dark-looking iron and sulfide particles as they shoot up through seawater. Found throughout the world's oceans, a number of vents even harbor eyeless shrimp, giant clams and other fauna rarely seen elsewhere.........

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August 1, 2006, 11:14 PM CT

Locating Storm-Fueling Moisture

People planning ball games, picnics, and other outdoor events may soon have more precise short-term forecasts of rainfall, thanks to an observing strategy now being tested by the National Center for Atmospheric Research (NCAR). An NCAR field project this summer is, for the first time, using multiple Doppler weather radars to track water vapor in the lower atmosphere. Measuring the low-level moisture is expected to help forecasters pin down the locations and timing of storms that might rage a few minutes to a few hours later.

The project is named REFRACTT (Refractivity Experiment For H2O Research And Collaborative operational Technology Transfer). Scientists are measuring changes in the speed of radar signals caused by refraction, which in turn reveal the presence or absence of atmospheric moisture. If the project proves successful, this refractivity technique could be added in the next few years to the national network of Doppler radars operated by NOAA's National Weather Service (NWS).

"Nobody's ever seen such high-resolution data on moisture before. We believe this could greatly help forecasters predict where heavy rains might develop," says NCAR scientist Rita Roberts, the lead principal investigator for REFRACTT.

REFRACTT runs from June 5 to August 11 and is being funded by the National Science Foundation, NCAR's primary sponsor. Along with four radars, researchers are using computer models, satellites, NCAR radionsondes (weather balloons), and ground-based sensors that intercept Global Positioning System signals and infer atmospheric moisture.........

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July 31, 2006, 11:02 PM CT

On The Trail Of Columbus' Sunken Ships

As luck would have it, time ran short, and the silt and mud in La Isabela Bay on the north coast of the Dominican Republic ran deep.

Despite these setbacks, Indiana University archaeologists are confident they are closer to discovering some of Christopher Columbus' lost ships -- and the answer to a 500-year-old mystery, "What was on those ships?".

"The discovery of a Columbus shipwreck, let alone the finding of the flagship Mariagalante, would be a tremendous contribution to maritime archaeology," said Charles Beeker, director of Academic Diving and Underwater Science Programs in IU Bloomington's School of Health, Physical Education and Recreation. "Perhaps more important would be the cargo. Were the ships laden with native Taino Indian artifacts heading to Spain? Such a find would shed new light on the nature of the contact period between the Old and the New Worlds."

Earlier this summer, Beeker and Geoffrey Conrad, director of IUB's Mathers Museum of World Cultures, took a team of faculty and graduate students to the Dominican Republic to explore intriguing magnetometer anomalies the IU scientists had discovered 10 years ago. The readings suggest large objects buried under silt and mud, and within coral colonies. The readings indicate also that the objects are scattered -- similar to how a shipwreck, or several for that matter, would appear -- in a 75-square-meter area.........

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July 29, 2006, 8:18 PM CT

Hurricane Season Adds to Red Tide

Researchers think that Florida's very active 2004 hurricane season may have played an important part in the development of extensive and long-lasting red tide conditions that affected its coastal areas in 2005.

The four hurricanes that crossed the Sunshine State in August and September 2004 dumped as much as 27 inches of rain (nearly double the historical values) in central Florida, which increased groundwater levels and rates of surface runoff. These two factors are thought to create conditions ripe for the bloom of a red tide.

Red tides, which may or may not be harmful, are primarily caused by the toxic phytoplankton, Karenia brevis on the west Florida Shelf. This species of phytoplankton can produce toxins that can kill marine organisms and lead to irritation of the eye and respiratory systems of animals and people.

Researchers Chuanmin Hu and Frank Muller-Karger of the University of South Florida, St. Petersburg, Fla., and Peter Swarzenski of U.S. Geological Survey, St. Petersburg, Fla., noted that several factors may have contributed to the 2005 red tide: the 2004 hurricanes and their heavy rain, runoff, and submarine (below the ocean floor) groundwater discharge. The researchers used NASA satellites, as well as observations from ships, buoys from the National Oceanic and Atmospheric Administration (NOAA), and geochemical tracers to study red tide.........

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July 25, 2006, 8:35 PM CT

Welcome to the Thunder Dome

As the heat builds during a blistering summer day in Atlanta, Georgia, you can almost hear the clouds overhead cry, "Let's get ready to rumble!".

Urban growth has transformed Atlanta's environment, creating a uniquely altered arena of weather. Because urban areas both generate and trap heat, a bubble or "urban heat island" forms around the city. The temperature in Atlanta is 5 to 8 degrees Fahrenheit higher than outlying areas, and this excess heat produces increased rainfall and thunderstorms.

This finding was presented at the annual meeting of the Association of American Geographers in Honolulu, Hawaii on March 24 by meteorologists Robert Bornstein and Qing Lu Lin from San Jose State University in California. Dale Quattrochi and Jeffrey Luvall of NASA's Global Hydrology Center lead this NASA-sponsored study. The Atlanta Land-use Analysis: Temperature and Air-quality (ATLANTA) project began in 1996 in order to study the impact of urban heat islands on the environment.

As the heat in a city builds, hot air rises. Colder air rushes into the vacuum, creating winds. The warmer ascending air forms clouds that drop water as they.

continue to rise. Bornstein and Lin observed that Atlanta's urban heat island causes convective clouds to form over the city.........

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July 25, 2006, 6:44 PM CT

Take Action To Avert Disaster

An MIT professor has joined nine other researchers in calling for government action to avert future disasters correlation to hurricanes.

The group challenged government and industry leaders to act to stop "our lemming-like march to the sea".

"We call upon leaders of government and industry to undertake a comprehensive evaluation of building practices, and insurance, land use and disaster relief policies that currently serve to promote an ever-increasing vulnerability to hurricanes," the researchers wrote.

In a joint statement, Kerry Emanuel, MIT professor of meteorology in the Department of Earth, Atmospheric and Planetary Sciences, joined other climate experts in asserting that the main hurricane problem facing the United States is "the ever-growing concentration of population and wealth in vulnerable coastal regions".

As per the scientists, "Rapidly escalating hurricane damage in recent decades owes much to government policies that serve to subsidize risk.

"State regulation of insurance is captive to political pressures that hold down premiums in risky coastal areas at the expense of higher premiums in less risky places," the statement says. "Federal flood insurance programs likewise undercharge property owners in vulnerable areas. Federal disaster policies, while providing obvious humanitarian benefits, also serve to promote risky behavior in the long run".........

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July 24, 2006, 11:36 PM CT

Sizing Up the Earth's Glaciers

Visit the world's high mountain ranges and you'll probably see less ice and snow today than you would have a few decades ago. More than 110 glaciers have disappeared from Montana's Glacier National Park over the past 150 years, and scientists estimate that the park's remaining 37 glaciers may be gone in another 25 years. Half a world away on the African equator, Hemingway's snows of Kilimanjaro are steadily melting and could completely disappear in the next 20 years. And in the Alps, glaciers are retreating and disappearing every year, much to the dismay of mountain climbers, tourist agencies, and environmental researchers.

"Receding and wasting glaciers are a telltale sign of global climate change," said Jeff Kargel, head of the Global Land Ice Measurements from Space (GLIMS) Coordination Center at the United States Geological Survey (USGS) in Flagstaff, Arizona. Kargel is part of a research team that's developing an inventory of the world's glaciers, combining current information on size and movement with historical data, maps, and photos.

In response to climate fluctuations, glaciers grow and shrink in length, width, and depth. Because glaciers are sensitive to the temperature and precipitation changes that accompany climate change, the rate of their growth or decline can serve as an indicator of regional and global climate change. Tracking and comparing recent and historical changes in the world's glaciers can help scientists understand global warming and its causes (such as natural fluctuations and human activities). Glacial changes can also have a more immediate impact on communities that rely on glaciers for their water supply, or on regions susceptible to floods, avalanches, or landslides triggered by abrupt glacial melt.........

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July 24, 2006, 11:29 PM CT

Glaciers in Alps May Disappear By 2100

During the last 150 years, a number of mountain ranges in Europe have lost a significant proportion of glacial extent, with strong acceleration occurring in the past two decades. To quantify past, as well as potentia,l evolution of the area and volume of glaciers within the European Alps in the context of impending climate change,.

Zemp et al. characterized the system using on-site measurements, remote sensing techniques, and numerical modeling. They observed that between 1850 and 1970, Alpine glaciers lost 35 percent of their total surface area; by 2000, almost 50 percent had disappeared. Their estimates also place current glacial volume at only one third of the 1850 value. Using models based on the rate of glacier loss, and predicted temperatures and precipitation levels over the next century, the authors determine that a 3 degree Celsius [5 degree Fahrenheit] warming of summer air would reduce the currently existing Alpine glacier cover by 80 percent. However, if temperatures were to rise by 5 degrees Celsius [9 degrees Fahrenheit], the Alps would be completely free of perennial surface ice by 2100.........

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July 24, 2006, 10:25 PM CT

Ice Sheets Drive Atmospheric Carbon Dioxide Levels

In the early 20th century, Milutin Milankovitch, a leading astronomer and climatologist of the time, proposed that the Earth's ice-age cycles could be predicted because they correspond directly with routine changes in the Earth's orbit and its tilt over cycles of tens of thousands of years. Because of these changes, there are predictable variations in the amount of solar radiation striking the Earth's surface. Milankovitch argued that low levels of summer radiation permit snow to accumulate according tomanent ice, while high levels of solar radiation melt snow and ice.

It all seemed so clean and simple.

And indeed the hypothesis was partially confirmed in the 1970s from marine sediment records extending through 2.75 million years of northern hemisphere ice-age cycles. As Milankovitch predicted, ice grew and melted at cycles of 23,000 and 41,000 years. But two observations were unexpected: from 2.75 until 0.9 million years ago, the ice sheets grew and melted almost entirely at the 41,000-year cycle. Since then, an oscillation near 100,000 years has dominated.

This knocked Milankovitch's theory for a loop.

Researchers have since turned to changes in atmospheric carbon dioxide as a possible explanation. Carbon dioxide concentrations can be measured in ancient air bubbles preserved in sequences of cores drilled into the Antarctic ice sheet. Because some changes in carbon dioxide have been found to occur slightly before changes in ice volume, the prevailing interpretation has been that carbon dioxide is an additional independent 'driver' of the size of ice sheets, along with solar radiation.........

Posted by: William      Permalink         Source

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