January 3, 2008, 9:47 PM CT

Plate tectonics may take a break

Plate tectonics, the geologic process responsible for creating the Earths continents, mountain ranges, and ocean basins, may be an on-again, off-again affair. Researchers have assumed that the shifting of crustal plates has been slow but continuous over most of the Earths history, but a new study from scientists at the Carnegie Institution suggests that plate tectonics may have ground to a halt at least once in our planets historyand may do so again.

A key aspect of plate tectonic theory is that on geologic time scales ocean basins are transient features, opening and closing as plates shift. Basins are consumed by a process called subduction, where oceanic plates descend into the Earths mantle. Subduction zones are the sites of oceanic trenches, high earthquake activity, and most of the worlds major volcanoes.

Writing in the January 4 issue of Science, Paul Silver of the Carnegie Institutions Department of Terrestrial Magnetism and former postdoctoral fellow Mark Behn (now at Woods Hole Oceanographic Institution) point out that most of todays subduction zones are located in the Pacific Ocean basin. If the Pacific basin were to close, as it is predicted to do about in 350 million years when the westward-moving Americas collide with Eurasia, then most of the planets subduction zones would disappear with it......... Posted by: Tyler      Read more         Source

January 3, 2008, 9:33 PM CT

North Atlantic warming tied to natural variability

A Duke University-led analysis of available records shows that while the North Atlantic Oceans surface waters warmed in the 50 years between 1950 and 2000, the change was not uniform. In fact, the subpolar regions cooled at the same time that subtropical and tropical waters warmed.

This striking pattern can be explained largely by the influence of a natural and cyclical wind circulation pattern called the North Atlantic Oscillation (NAO), wrote authors of a study published Thursday, Jan. 3, in Science Express, the online edition of the journal Science.

Winds that power the NAO are driven by atmospheric pressure differences between areas around Iceland and the Azores. The winds have a tremendous impact on the underlying ocean, said Susan Lozier, a professor of physical oceanography at Dukes Nicholas School of the Environment and Earth Sciences who is the studys first author.

Other studies cited in the Science Express report suggest human-caused global warming may be affecting recent ocean heating trends. But Lozier and her coauthors found their data cant support that view for the North Atlantic. It is premature to conclusively attribute these regional patterns of heat gain to greenhouse warming, they wrote.

The take-home message is that the NAO produces strong natural variability, said Lozier in an interview. The simplistic view of global warming is that everything forward in time will warm uniformly. But this very strong natural variability is superimposed on human-caused warming. So scientists will need to unravel that natural variability to get at the part humans are responsible for......... Posted by: Tyler      Read more         Source

Fri, 28 Dec 2007 14:31:34 GMT

Nobel Week

Nobel Week is coming to a close. This year''s highlight was Al Gore''s Nobel Lecture on the dangers of global climate change. Gore says, "We are what is wrong, and we must make it right."

Gore states unequivocally that CO2 is pollution, and the consequences of its accumulation are devastating.
"Last September 21, as the Northern Hemisphere tilted away from the sun, scientists reported with unprecedented distress that the North Polar ice cap is "falling off a cliff." One study estimated that it could be completely gone during summer in less than 22 years. Another new study, to be presented by U.S. Navy researchers later this week, warns it could happen in as little as 7 years.

Seven years from now.

In the last few months, it has been harder and harder to misinterpret the signs that our world is spinning out of kilter. Major cities in North and South America, Asia and Australia are nearly out of water due to massive droughts and melting glaciers. Desperate farmers are losing their livelihoods. Peoples in the frozen Arctic and on low-lying Pacific islands are planning evacuations of places they have long called home. Unprecedented wildfires have forced a half million people from their homes in one country and caused a national emergency that almost brought down the government in another. Climate refugees have migrated into areas already inhabited by people with different cultures, religions, and traditions, increasing the potential for conflict. Stronger storms in the Pacific and Atlantic have threatened whole cities. Millions have been displaced by massive flooding in South Asia, Mexico, and 18 countries in Africa. As temperature extremes have increased, tens of thousands have lost their lives. We are recklessly burning and clearing our forests and driving more and more species into extinction. The very web of life on which we depend is being ripped and frayed."

He singles out, USA and China for action: "But the outcome will be decisively influenced by two nations that are now failing to do enough: the United States and China. [I]t should be absolutely clear that it is the two largest CO2 emitters – most of all, my own country – that will need to make the boldest moves, or stand accountable before history for their failure to act."

Quoting Henrik Isben, Gore says, ""One of these days, the younger generation will come knocking at my door."

They will ask either, ""What were you thinking; why didn''t you act? "Or they will ask instead: "How did you find the moral courage to rise and successfully resolve a crisis that so many said was impossible to solve?"

When the next generation knocks on your door, what are you going to say?

The full text is available here.

Photo: Scanpix/Tom Hevezi Posted by: Dennehy      Read more     Source

December 27, 2007, 9:05 AM CT

Housewives are more ecologically aware

Research carried out in the Department of Social Psychology and Methodology of Behaviour Sciences of the University of Granada has shown that the level of academic training is not correlation to the ecological awareness of people, despite the great proliferation of programs designed to educate and increase social awareness of the environment. Thus, as per research, housewives are more ecologically aware than university students, given they are more willing to recycle glass.

This research was carried out by doctor María del Carmen Aguilar Luzon under the direction of professor J. Miguel Ángel García Martínez. The environmental behaviour chosen for the study was the separating of glass from other garbage. In the study, a sample of 525 university students and 154 housewives was used. Existing differences between both groups are significant: housewives are more willing to separate glass from other garbage, have a more favourable attitude towards recycling, and have enough willpower to do it.

Less control.

However, the researcher points out that university students "have less control over glass recycling behaviour, given they perceive it as a series of barriers and limitations hard to overcome." The container being far from home and they having to make their way to it while carrying heavy bags full of glass, for example, is viewed as a difficulty for students, and not for housewives. In fact, housewives adopt environmentally friendly practices more often than students......... Posted by: Tyler      Read more         Source

December 20, 2007, 9:23 PM CT

El Nio affected by global warming

The climatic event El Nio, literally the Baby Jesus, was given its name because it generally occurs at Christmas time along the Peruvian coasts. This expression of climatic variability, also called El Nio Southern Oscillation (ENSO), results from a series of interactions between the atmosphere and the tropical ocean. It induces drought in areas that normally receive abundant rain and, on the other hand, heavy rainfall and floods in commonly arid desert zones. Researchers term this phenomenon a quasi-cyclic variation because its periodicity, which varies from 2 to 7 years, shows no regular time pattern. Research conducted over the past 25 years, by oceanographers, climatologists and meteorologists has much improved knowledge on the mechanisms generating an El Nio event. However, possible influence of other systems of climate variability on the ENSO regime is more difficult to fathom. More particularly, it is not known if the intensity and frequency of the event is susceptible to modification in a situation of global warming.

The research work recently published by a team of Chilean and IRD researchers sheds new light on El Nios variability. Several geochemical factors contained in a drill core sediment sampled from 80 m depth under the Bay of Mejillones, in northern Chile, were determined. Analysis of breakdown byproducts from diatoms, unicellular planktonic algae, yielded an accurate trace of this regions trends in sea surface temperature between 1650 and 2000. Data for the period 1820-1878 showed a fall of over 2C. This temperature decrease was also detected in two cores collected near the South-American coasts, over 1000 km to the North and South of Mejillones......... Posted by: Tyler      Read more         Source

December 20, 2007, 9:15 PM CT

Greenhouse gases and the evolution of C4 grasses

How a changing climate can affect ecosystems is an important and timely question, particularly considering the recent global rise in greenhouse gases. Now, in an article published online on December 20th in the journal Current Biology, evolutionary biologists provide good evidence that changes in global carbon dioxide levels probably had an important influence on the emergence of a specific group of plants, termed C4 grasses, which includes major cereal crops, plants used for biofuels, and species that represent important components of grasslands across the world.

C4 plants are specially equipped to combat an energetically costly process, known as photorespiration, that can occur under conditions of high temperature, drought, high salinity, andith relevance to these latest findingslow carbon dioxide levels. Eventhough a combination of any of these factors might have provided the impetus behind the evolution of the various C4 lineages, it had been widely speculated that a drop in global carbon dioxide levels, occurring approximately 30 million years ago during the Oligocene period, may have been the major driving force. Establishing the link between the two, however, has proven difficult partly because there are no known fossils of C4 plants from this period. Enter Pascal-Antoine Christin and his colleagues from the University of Lausanne, Switzerland, who decided to take an alternative approach to date a large group of grasses. By using a molecular clock technique, the authors were able to determine that the Chloridoideae subfamily of grasses emerged approximately 30 million years ago, right around the time global carbon dioxide levels were dropping. Furthermore, a model of the evolution of these grasses suggests that this correlation is not a trivial coincidence and instead reflects a causal relationship......... Posted by: Tyler      Read more         Source

December 20, 2007, 8:49 PM CT

About Methane Bubbling Up From the Ocean Floor

Methane, a potent greenhouse gas, is emitted in great quantities as bubbles from seeps on the ocean floor near Santa Barbara. About half of these bubbles dissolve into the ocean, but the fate of this dissolved methane remains uncertain. Scientists at the University of California, Santa Barbara have discovered that only one percent of this dissolved methane escapes into the air -- good news for the Earth's atmosphere.

Coal Oil Point (COP), one of the world's largest and best studied seep regions, is located along the northern margin of the Santa Barbara Channel. Thousands of seep fields exist in the ocean bottom around the world, as per David Valentine, associate professor of Earth Science at UC Santa Barbara. Valentine along with other members of UCSB's seeps group studied the plume of methane bubbles that flows from the seeps at COP.

Their results will soon be published as the cover story in Volume 34 of Geophysical Research Letters. This research effort is the first time that the gas that dissolves and moves away from COP, the plume, has been studied.

The amount of methane release from COP seeps is around two million cubic feet per day, as per Valentine. About 100 barrels of oil oozes out of this area as well. Methane warms the Earth 23 times more than carbon dioxide when averaged over a century. Thus the fate of the methane bubbles from the seeps is an important environmental question......... Posted by: Tyler      Read more         Source

December 12, 2007, 9:58 PM CT

Without its insulating ice cap

Record-breaking amounts of ice-free water have deprived the Arctic of more of its natural "sunscreen" than ever in recent summers. The effect is so pronounced that sea surface temperatures rose to 5 C above average in one place this year, a high never before observed, says the oceanographer who has compiled the first-ever look at average sea surface temperatures for the region.

Such superwarming of surface waters can affect how thick ice grows back in the winter, as well as its ability to withstand melting the next summer, as per Michael Steele, an oceanographer with the University of Washington's Applied Physics Laboratory. Indeed, since September, the end of summer in the Arctic, winter freeze-up in some areas is two months later than usual.

The extra ocean warming also might be contributing to some changes on land, such as previously unseen plant growth in the coastal Arctic tundra, if heat coming off the ocean during freeze-up is making its way over land, says Steele, who is speaking Wednesday at the American Geophysical Union meeting in San Francisco.

He is lead author of "Arctic Ocean surface warming trends over the past 100 years," accepted for publication in AGU's Geophysical Research Letters. Co-authors are physicist Wendy Ermold and research scientist Jinlun Zhang, both of the UW Applied Physics Laboratory. The work is funded by the National Science Foundation......... Posted by: Tyler      Read more         Source

December 11, 2007, 10:21 PM CT

Greenland melt accelerating

The 2007 melt extent on the Greenland ice sheet broke the 2005 summer melt record by 10 percent, making it the largest ever recorded there since satellite measurements began in 1979, as per a University of Colorado at Boulder climate scientist.

The melting increased by about 30 percent for the western part of Greenland from 1979 to 2006, with record melt years in 1987, 1991, 1998, 2002, 2005 and 2007, said CU-Boulder Professor Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences. Air temperatures on the Greenland ice sheet have increased by about 7 degrees Fahrenheit since 1991, primarily a result of the build-up of greenhouse gases in Earths atmosphere, as per scientists.

Steffen gave a presentation on his research at the fall meeting of the American Geophysical Union held in San Francisco from Dec. 10 to Dec. 14. His team used data from the Defense Meteorology Satellite Programs Special Sensor Microwave Imager aboard several military and weather satellites to chart the area of melt, including rapid thinning and acceleration of ice into the ocean at Greenlands margins.

Steffen maintains an extensive climate-monitoring network of 22 stations on the Greenland ice sheet known as the Greenland Climate Network, transmitting hourly data via satellites to CU-Boulder to study ice-sheet processes......... Posted by: Tyler      Read more         Source

December 11, 2007, 8:28 PM CT

Himalayan Ice Fields Haven't Grown In Last 50 Years

Ice cores drilled last year from the summit of a Himalayan ice field lack the distinctive radioactive signals that mark virtually every other ice core retrieved worldwide.

That missing radioactivity, originating as fallout from atmospheric nuclear tests during the 1950s and 1960s, routinely provides scientists with a benchmark against which they can gauge how much new ice has accumulated on a glacier or ice field.

In 2006, a joint U.S.-Chinese team drilled four cores from the summit of Naimona'nyi, a large glacier 6,050 meters (19,849 feet) high on the Tibetan Plateau.

The scientists routinely analyze ice cores for a host of indicators - particulates, dust, oxygen isotopes, etc. -- that can paint a picture of past climate in that region.

Researchers think that the missing signal means that this Tibetan ice field has been shrinking at least since the A-bomb test half a century ago. If true, this could foreshadow a future when the stockpiles of freshwater will dwindle and vanish, seriously affecting the lives of more than 500 million people on the Indian subcontinent.

"There's about 12,000 cubic kilometers (2,879 cubic miles) of fresh water stored in the glaciers throughout the Himalayas - more freshwater than in Lake Superior," explained Lonnie Thompson, distinguished university professor of earth sciences at Ohio State University and a researcher with the Byrd Polar Research Center on campus......... Posted by: Tyler      Read more         Source