November 28, 2006, 8:58 PM CT

Solar Brightness And Global Warming

Changes in the Sun's brightness over the past millennium have had only a small effect on Earth's climate, according to a review of existing results and new calculations performed by researchers in the United States, Switzerland, and Germany.

The review, led by Peter Foukal (Heliophysics, Inc.), appears in the September 14 issue of Nature. Among the coauthors is Tom Wigley of the National Center for Atmospheric Research. NCAR's primary sponsor is the National Science Foundation.

"Our results imply that, over the past century, climate change due to human influences must far outweigh the effects of changes in the Sun's brightness," says Wigley.

Reconstructions of climate over the past millennium show a warming since the 17th century, which has accelerated dramatically over the past 100 years. Many recent studies have attributed the bulk of 20th-century global warming to an increase in greenhouse gas concentrations in the atmosphere. Natural internal variability of Earth's climate system may also have played a role. However, the discussion is complicated by a third possibility: that the Sun's brightness could have increased.

The new review in Nature examines the factors observed by astronomers that relate to solar brightness. It then analyzes how those factors have changed along with global temperature over the last 1,000 years.........

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November 26, 2006, 7:35 AM CT

New Meaning To Term 'Older Than Dirt'

A especially resilient type of carbon from the first plants to regrow after the last ice age and that same type of carbon from all the plants since appears to have been accumulating for 11,000 years in the forests of British Columbia, Canada.

It's as if the carbon, which comes from the waxy material plants generate to protect their foliage from sun and weather, has been going into a bank account where only deposits are being made and virtually no withdrawals.

Modelers of the Earth's carbon cycle, who've worked on the assumption that this type of carbon remains in the soils only 1,000 to 10,000 years before microorganisms return it to the atmosphere as carbon dioxide, will need to revise their thinking if findings published in the Nov. 24 issue of Science are typical of other northern forests.

"Our results about the resilience of this particular kind of carbon suggest that the turnover time of this carbon pool may be 10,000 to 100,000 years," says Rienk Smittenberg, a research associate with the University of Washington School of Oceanography and lead author of the paper. He did the work while at the Royal Netherlands Institute of Sea Research.

Soils harbor the third-largest pool of carbon in the world behind the carbon locked deep in the Earth as fossil fuel oils and coal and the carbon that is dissolved in the world's oceans.........

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November 26, 2006, 7:28 AM CT

First Look At Seafloor Formation

Ordinarily, losing almost all of one's instruments would be considered a severe setback to any scientist. But when Maya Tolstoy, a marine geophysicist at the Lamont-Doherty Earth Observatory, a member of the Earth Institute at Columbia University, recently learned that two-thirds of the seismometers she placed on the floor of the Pacific Ocean were trapped more than 8,000 feet (2500 meters) underwater, it turned out to be an extremely good sign.

Tolstoy and Lamont-Doherty colleague Felix Waldhauser set an array of ocean bottom seismometers along a section of the East Pacific Rise off the coast of Mexico in 2003 to study the little-understood process of seafloor spreading--a process that is responsible for the formation of nearly three-quarters of the Earth's crust. When a team went back in April 2006 to retrieve the instruments, however, only four out of 12 responded to the coded release signal and bobbed to the surface; three more responded to the signal, but did not come up. The rest remained silent.

Tests of the water temperature and light-scattering near the sea floor revealed signs of a recent volcanic eruption. A second expedition led by James Cowen of the University of Hawaii on the research vessel R/V New Horizon in early May lowered a camera that confirmed what the researchers suspected: Their instruments had been directly on top of a section of the East Pacific Rise that erupted and were trapped in fresh lava flows.........

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November 26, 2006, 7:22 AM CT

Insights Into Heat Flow Deep In Earth

Earth's interior is not a non-malignant world that only stores the geologic history of our planet. Geologists now see the normally assumed placid inner Earth as a dynamic environment filled with exotic materials and substances roiling under intense heat and pressures. It is an environment that continues to evolve in interesting ways and one that has an impact on what happens at its surface.

The latest evidence of this dynamic inner Earth is revealed in a recent series of measurements that peered deep within Earth, halfway to its center. The new experiments have yielded important results that help determine temperature halfway to the center of Earth. It also has implications for the age of Earth's solid inner core and how its magnetic field may be generated.

"We have found unexpected rock layering in Earth's deepest mantle," said Edward Garnero of ASU's School of Earth and Space Exploration and one of the scientists on the team. "The implications of the layering are far reaching, with intimate connections to the rock chemistry, temperature and convective flow, all of which have been previously inaccessible".

"Understanding of Earth's core-mantle boundary environment puts us in the position of answering a host of important questions, such as how much heat from the molten outer core cooks the overlying mantle," Garnero explained. "While this might seem distant and esoteric, it actually relates to the vigor of convective mantle flow that ultimately jostles Earth's surface with volcanic and earthquake processes".........

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November 26, 2006, 7:02 AM CT

Unique View Of Underwater Eruption

A combination of luck and being in the right place at the right time allowed a University of Florida geologist and other researchers to capture and record an undersea volcanic eruption for the first time ever.

The eruption, which took place early this spring thousands of feet below the surface of the Pacific Ocean, is described in a paper set for release Thursday in Science Express, the journal Sciences online magazine.

Never before have we had instruments in place like this that recorded an eruptive event on the seafloor, said Mike Perfit, a UF professor of geology.

Perfit was among the researchers who visited the eruption shortly after it took place aboard the deep-sea submersible Alvin. The project was headed by Maya Tolstoy, a seismologist with Columbia Universitys Lamont Doherty Earth Observatory and the lead author of the Science paper.

Perfit said the eruption occurred about 400 miles west of Mexico along a massive volcanic mountain range called the East Pacific Rise. Fortuitously, it was one of three active undersea volcanic areas that were selected for high-intensity research in the late 1990s as part of the National Science Foundations RIDGE research program. As a result, geologists, biologists, geophysicists and other specialists had gathered a storehouse of samples, data and photos from the site.........

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November 26, 2006, 6:55 AM CT

Impact of climate change in Africa

Africa is the continent that will suffer most under global warming. Past history gives us lessons on the likely effects of future climate change. Of greatest concern are the 'large infrequent disturbances' to the climate as these will have the most devastating effects. In a remarkable study from the Kenyan Tsavo National Park published recently in the African Journal of Ecology, Dr Lindsey Gillson uncovers evidence for a drought that coincided with the harrowing period of Maasai history at the end of the 19th century termed "Emutai" meaning to wipe out.

"Severe disturbance events and rapid environmental change tend to occur infrequently, but can have a lasting effect on both environment and society" says Dr Gillson. This was no-where more evident than in the case of the Maasai "Emutai". The period 1883-1902 was marked by epidemics of bovine pleuropneumonia, rinderpest and small pox. The rains failed completely in 1897 and 1898. The Austrian explorer Dr Oscar Baumann, who travelled in Maasailand in 1891, wrote chilling eye-witness accounts of the horror experienced during a large ecological disturbance:

"There were women wasted to skeletons from whose eyes the madness of starvation glared. warriors scarcely able to crawl on all fours, and apathetic, languishing elders. Swarms of vultures followed them from high, awaiting their certain victims." (Baumann 1894, Masailand).........

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November 21, 2006, 8:52 PM CT

Historic Volcanic Eruption Shrunk the Mighty Nile

Volcanic eruptions in high latitudes can greatly alter climate and distant river flows, including the Nile, as per a recent study funded in part by NASA.

Scientists observed that Iceland's Laki volcanic event, a series of about ten eruptions from June 1783 through February 1784, significantly changed atmospheric circulations across much of the Northern Hemisphere. This created unusual temperature and precipitation patterns that peaked in the summer of 1783, including far below normal rainfall over much of the Nile River watershed and record low river levels.

The study provides new evidence that large volcanic eruptions north of the equator often have far different impacts on climate than those in the tropics. "While considerable research has shown that eruptions in the tropics influence climate in the Northern Hemisphere winter, this study indicates that eruptions in high-latitudes produce changes in atmospheric circulation in the Northern Hemisphere summer," said lead author Luke Oman, Rutgers University, New Brunswick, N.J. Using a sophisticated computer model developed by NASA's Goddard Institute for Space Studies, New York, the scientists linked the Laki eruptions to a cascade of effects that rippled across much of the Northern Hemisphere, altering surface temperatures that ultimately resulted in much below normal rainfall over the Sahel of Africa and record low water levels on the Nile River for up to a year. The Sahel is a stretch of land from the Atlantic Ocean to the "Horn of Africa" that includes the Sahara Desert and savanna areas with sparse vegetation.........

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November 16, 2006, 8:43 PM CT

Origin Of Appalachian Mountains

Geologists have developed a new theory to explain how and when the Appalachian Mountain range was created. Their research redraws the map of the planet from 420 million years ago.

The researchers recently discovered a piece of the Appalachian Mountains in southern Mexico, a location geologists long had assumed was part of the North American Cordillera. The Cordillera is a continuous sequence of mountain ranges that includes the Rocky Mountains. It stretches from Alaska to Mexico and continues into South America.

For the past decade, geologists have collected information from Mexico's Acatlán Complex, a rock outcropping the size of Massachusetts. As they uncovered each new piece of data from the complex, evidence contradicting earlier assumptions about the origins of that part of Mexico emerged.

"It was a story that had the Appalachians written all over it," said Damian Nance, Ohio University professor of geological sciences and lead author of an article detailing the findings, which was reported in the recent issue of Geology. "This will change the way geologists look at Mexico".

It also changes existing theory regarding the creation of the Appalachians, which has radically altered scientists' understanding of the planet's geography, said Nance. Age data, newly unearthed fossils and chemical analysis of the rocks show that the complex is much younger than previously thought. It records a pivotal part of the Appalachian story not preserved elsewhere.........

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November 14, 2006, 5:02 AM CT

Ice-breaker Polarstern to explore uncharted seafloor

Huge areas of sea floor (around 3,250 km²) have been freed up by the collapse 4 years ago of the Larsen B platform along the Antarctic Peninsula - leaving a blank spot on Antarctic maps. Polarstern, the research flagship of the Alfred Wegener Institute for Polar and Marine Research, will shortly conduct there the first major biological research, studying living communities, from microbes to whales, including bottom fish and squids.

THE ITINERARY

DEPARTURE - NOVEMBER 23, 2006: CAPE TOWN.

The Polarstern leaves Cape Town, South Africa, heading towards the Weddell Sea (1).

DECEMBER 4/5 TO DECEMBER 14, 2006: NEUMAYER STATION.

The Polarstern stops in the Atka Bay in order to supply the German Neumayer Research Station (2).

DECEMBER 14 TO JANUARY 26, 2006: ANTARCTIC PENINSULA.

The first investigations, on living resources (CCAMLR), take place on the western side of the Antarctic Peninsula, around the South Shetland Islands (3). The subsequent ecological work (CAML) is located around the Larsen A/B area. If the sea ice is not penetrable, an alternative area around Joinville Island will be used instead (4).

ARRIVAL - JANUARY 30, 2007: PUNTA ARENAS.

The Polarstern will end its expedition in Punta Arenas, Chile on January 30, 2007 (5).........

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November 13, 2006, 9:03 PM CT

Phosphorus Another Culprit

Nitrogen is flowing down the Mississippi River and into the Gulf of Mexico faster than it can be consumed by floating microscopic plants called phytoplankton, increasing the size of the "dead zone" off the Louisiana coast. The findings, based on analysis of data gathered in 2001, are published online this week in the journal Environmental Science and Technology.

Because of the increased nitrogen levels, phytoplankton blooms are growing, and the Gulf's hypoxia zone -- an area lacking enough oxygen to sustain most life -- is getting bigger.

"In a pristine system, nutrients would flow down the river and into the Gulf, and there would be limited phytoplankton growth and no hypoxia," said James Ammerman, co-author of the paper and a biological oceanographer at Rutgers. "Heavy use of fertilizers containing nitrogen and phosphorus in the agriculture of the Mississippi Valley has thrown the system out of balance".

As per Ammerman, phytoplankton need both nitrogen and phosphorus to grow. Because they require a 16-to-1 ratio of nitrogen to phosphorus, phytoplankton commonly run out of nitrogen first; most coastal surface waters have ratios lower than 16-to-1.

"There is now so much nitrogen in the Gulf that even though phytoplankton consume it faster than they consume phosphorus, they can't get rid of it fast enough, and it's the phosphorus, instead of nitrogen, that runs out first and becomes the limiting nutrient," Ammerman said.........

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