Geologists Say 'Wall Of Africa' Allowed Humanity To Emerge

Source:

http://www.sciencedaily.com/releases/2007/12/071219082604.htm

ScienceDaily (Dec. 22, 2007) — Scientists long have focused on how climate and vegetation allowed human ancestors to evolve in Africa. Now, University of Utah geologists are calling renewed attention to the idea that ground movements formed mountains and valleys, creating environments that favored the emergence of humanity.

"Tectonics [movement of Earth's crust] was ultimately responsible for the evolution of humankind," Royhan and Nahid Gani of the university's Energy and Geoscience Institute write in the January, 2008, issue of Geotimes, published by the American Geological Institute.
They argue that the accelerated uplift of mountains and highlands stretching from Ethiopia to South Africa blocked much ocean moisture, converting lush tropical forests into an arid patchwork of woodlands and savannah grasslands that gradually favored human ancestors who came down from the trees and started walking on two feet -- an energy-efficient way to search larger areas for food in an arid environment.
In their Geotimes article, the Ganis -- a husband-and-wife research team who met in college in their native Bangladesh -- describe this 3,700-mile-long stretch of highlands and mountains as "the Wall of Africa." It parallels the famed East African Rift valley, where many fossils of human ancestors were found.
"Because of the crustal movement or tectonism in East Africa, the landscape drastically changed over the last 7 million years," says Royhan Gani (pronounced rye-hawn Go-knee), a research assistant professor of civil and environmental engineering. "That landscape controlled climate on a local to regional scale. That climate change spurred human ancestors to evolve from apes."
Hominins -- the new scientific word for humans (Homo) and their ancestors (including Ardipithecus, Paranthropus and Australopithecus) -- split from apes on the evolutionary tree roughly 7 million to 4 million years ago. Royhan Gani says the earliest undisputed hominin was Ardipithecus ramidus 4.4 million years ago. The earliest Homo arose 2.5 million years ago, and our species, Homo sapiens, almost 200,000 years ago.
Tectonics -- movements of Earth's crust, including its ever-shifting tectonic plates and the creation of mountains, valleys and ocean basins -- has been discussed since at least 1983 as an influence on human evolution.
But Royhan Gani says much previous discussion of how climate affected human evolution involves global climate changes, such as those caused by cyclic changes in Earth's orbit around the sun, and not local and regional climate changes caused by East Africa's rising landscape.
A Force from within the Earth
The geological or tectonic forces shaping Africa begin deep in the Earth, where a "superplume" of hot and molten rock has swelled upward for at least the past 45 million years. This superplume and its branching smaller plumes help push apart the African and Arabian tectonic plates of Earth's crust, forming the Red Sea, Gulf of Aden and the Great Rift Valley that stretches from Syria to southern Africa.
As part of this process, Africa is being split apart along the East African Rift, a valley bounded by elevated "shoulders" a few tens of miles wide and sitting atop "domes" a few hundreds of miles wide and caused by upward bulging of the plume.
The East African Rift runs about 3,700 miles from the Ethiopian Plateau south-southwest to South Africa's Karoo Plateau. It is up to 370 miles wide and includes mountains reaching a maximum elevation of about 19,340 feet at Mount Kilimanjaro.
The rift "is characterized by volcanic peaks, plateaus, valleys and large basins and freshwater lakes," including sites where many fossils of early humans and their ancestors have been found, says Nahid Gani (pronounced nah-heed go-knee), a research scientist. There was some uplift in East Africa as early as 40 million years ago, but "most of these topographic features developed between 7 million and 2 million years ago."
A Wall Rises and New Species Evolve
"Although the Wall of Africa started to form around 30 million years ago, recent studies show most of the uplift occurred between 7 million and 2 million years ago, just about when hominins split off from African apes, developed bipedalism and evolved bigger brains," the Ganis write.
"Nature built this wall, and then humans could evolve, walk tall and think big," says Royhan Gani. "Is there any characteristic feature of the wall that drove human evolution?"
The answer, he believes, is the variable landscape and vegetation resulting from uplift of the Wall of Africa, which created "a topographic barrier to moisture, mostly from the Indian Ocean" and dried the climate. He says that contrary to those who cite global climate cycles, the climate changes in East Africa were local and resulted from the uplift of different parts of the wall at different times.
Royhan Gani says the change from forests to a patchwork of woodland and open savannah did not happen everywhere in East Africa at the same time, and the changes also happened in East Africa later than elsewhere in the world.
The Ganis studied the roughly 300-mile-by-300-mile Ethiopian Plateau -- the most prominent part of the Wall of Africa. Previous research indicated the plateau reached its present average elevation of 8,200 feet 25 million years ago. The Ganis analyzed rates at which the Blue Nile River cut down into the Ethiopian Plateau, creating a canyon that rivals North America's Grand Canyon. They released those findings in the September 2007 issue of GSA Today, published by the Geological Society of America.
The conclusion: There were periods of low-to-moderate incision and uplift between 29 million and 10 million years ago, and again between 10 million and 6 million years ago, but the most rapid uplift of the Ethiopian Plateau (by some 3,200 vertical feet) happened 6 million to 3 million years ago.
The Geotimes paper says other research has shown the Kenyan part of the wall rose mostly between 7 million and 2 million years ago, mountains in Tanganyika and Malawi were uplifted mainly between 5 million and 2 million years ago, and the wall's southernmost end gained most of its elevation during the past 5 million years.
"Clearly, the Wall of Africa grew to be a prominent elevated feature over the last 7 million years, thereby playing a prominent role in East African aridification by wringing moisture out of monsoonal air moving across the region," the Ganis write. That period coincides with evolution of human ancestors in the area.
Royhan Gani says the earliest undisputed evidence of true bipedalism (as opposed to knuckle-dragging by apes) is 4.1 million years ago in Australopithecus anamensis, but some believe the trait existed as early as 6 million to 7 million years ago.
The Ganis speculate that the shaping of varied landscapes by tectonic forces -- lake basins, valleys, mountains, grasslands, woodlands -- "could also be responsible, at a later stage, for hominins developing a bigger brain as a way to cope with these extremely variable and changing landscapes" in which they had to find food and survive predators.
For now, Royhan Gani acknowledges the lack of more precise timeframes makes it difficult to link specific tectonic events to the development of upright walking, bigger brains and other key steps in human evolution.
"But it all happened within the right time period," he says. "Now we need to nail it down."
Adapted from materials provided by University of Utah.

Fausto Intilla

www.oloscience.com

Without Its Insulating Ice Cap, Arctic Surface Waters Warm To As Much As 5 C Above Average

Source:

http://www.sciencedaily.com/releases/2007/12/071212201236.htm

ScienceDaily (Dec. 17, 2007) — 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, according to 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 spoke December 12 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.
"Warming is particularly pronounced since 1995, and especially since 2000," the authors write. The spot where waters were 5 C above average was in the region just north of the Chakchi Sea. The historical average temperature there is -1 C -- remember that the salt in ocean water keeps it liquid at temperatures that would cause fresh water to freeze. This year water in that area warmed to 4 C, for a 5-degree change from the average.
That general area, the part of the ocean north of Alaska and Eastern Siberia that includes the Bering Strait and Chukchi Sea, experienced the greatest summer warming. Temperatures for that region were generally 3.5 C warmer than historical averages and 1.5 C warmer than the historical maximum.
Such widespread warming in those areas and elsewhere in the Arctic is probably the result of having increasing amounts of open water in the summer that readily absorb the sun's rays, Steele says. Hard, white ice, on the other hand, can work as a kind of sunscreen for the waters below, reflecting rather than absorbing sunlight. The warming also may be partly caused by increasing amounts of warmer water coming from the Pacific Ocean, something scientists have noted in recent years.
The Arctic was primed for more open water since the early 1990s as the sea-ice cover has thinned, due to a warming atmosphere and more frequent strong winds sweeping ice out of the Arctic Ocean via Fram Strait into the Atlantic Ocean where the ice melts. The wind effect was particularly strong in the summer of 2007.
Now the situation could be self-perpetuating, Steele says. For example, he calculates that having more heat in surface waters in recent years means 23 to 30 inches less ice will grow in the winter than formed in 1965. Since sea ice typically grows about 80 inches in a winter, that is a significant fraction of ice that's going missing, he says.
Then too, higher sea surface temperatures can delay the start of freeze-up because the extra heat must be discharged from the upper ocean before ice can form. "The effect on net winter growth would probably be negligible for a delay of several weeks, but could be substantial for delays of several months," the authors write.
The work is funded by the National Science Foundation.
Adapted from materials provided by University of Washington.

Fausto Intilla

www.oloscience.com

Natural Climate Changes Can Intensify Hurricanes More Efficiently Than Global Warming

Source:

http://www.sciencedaily.com/releases/2007/12/071212201954.htm

ScienceDaily (Dec. 13, 2007) — Natural climate variations, which tend to involve localized changes in sea surface temperature, may have a larger effect on hurricane activity than the more uniform patterns of global warming, a report in Nature suggests.

In the debate over the effect of global warming on hurricanes, it is generally assumed that warmer oceans provide a more favorable environment for hurricane development and intensification. However, several other factors, such as atmospheric temperature and moisture, also come into play.
Drs. Gabriel A. Vecchi of the NOAA Geophysical Fluid Dynamics Laboratory and Brian J. Soden from the University of Miami Rosenstiel School of Marine & Atmospheric Science analyzed climate model projections and observational reconstructions to explore the relationship between changes in sea surface temperature and tropical cyclone 'potential intensity' - a measure that provides an upper limit on cyclone intensity.
They found that warmer oceans do not alone produce a more favorable environment for storms because the effect of remote warming can counter, and sometimes overwhelm, the effect of local surface warming. "Warming near the storm acts to increase the potential intensity of hurricanes, whereas warming away from the storms acts to decrease their potential intensity," Vecchi said.
Their study found that long-term changes in potential intensity are more closely related to the regional pattern of warming than to local ocean temperature change. Regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. "A surprising result is that the current potential intensity for Atlantic hurricanes is about average, despite the record high temperatures of the Atlantic Ocean over the past decade." Soden said. "This is due to the compensating warmth in other ocean basins."
"As we try to understand the future changes in hurricane intensity, we must look beyond changes in Atlantic Ocean temperature. If the Atlantic warms more slowly than the rest of the tropical oceans, we would expect a decrease in the upper limit on hurricane intensity," Vecchi added. "This is an interesting piece of the puzzle."
"While these results challenge some current notions regarding the link between climate change and hurricane activity, they do not contradict the widespread scientific consensus on the reality of global warming," Soden noted.
The journal article is entitled "Effect of Remote Sea Surface Temperature Change on Tropical Cyclone Potential Intensity."
Adapted from materials provided by University of Miami Rosenstiel School of Marine & Atmospheric Science.

Fausto Intilla

www.oloscience.com

Source:

http://www.sciencedaily.com/releases/2007/12/071213101419.htm

ScienceDaily (Dec. 13, 2007) — The decade of 1998-2007 is the warmest on record, according to data sources obtained by the World Meteorological Organization (WMO). The global mean surface temperature for 2007 is currently estimated at 0.41°C/0.74°F above the 1961-1990 annual average of 14.00°C/57.20°F.

The University of East Anglia and the Met Office's Hadley Centre have released preliminary global temperature figures for 2007, which show the top 11 warmest years all occurring in the last 13 years. The provisional global figure for 2007 using data from January to November, currently places the year as the seventh warmest on records dating back to 1850.
Other remarkable global climatic events recorded so far in 2007 include record-low Arctic sea ice extent, which led to first recorded opening of the Canadian Northwest Passage; the relatively small Antarctic Ozone Hole; development of La Niña in the central and eastern Equatorial Pacific; and devastating floods, drought and storms in many places around the world.
The preliminary information for 2007 is based on climate data up to the end of November from networks of land-based weather stations, ships and buoys, as well as satellites. The data are continually collected and disseminated by the National Meteorological and Hydrological Services (NMHS) of WMO’s 188 Members and several collaborating research institutions. Final updates and figures for 2007 will be published in March 2008 in the annual WMO brochure for the Statement on the Status of the Global Climate.
WMO’s global temperature analyses are based on two different sources. One is the combined dataset maintained by both the Hadley Centre of the UK Meteorological Office, and the Climatic Research Unit, University of East Anglia, UK, which at this stage ranked 2007 as the seventh warmest on record. The other dataset is maintained by the US Department of Commerce’s National Oceanic and Atmospheric Administration (NOAA), which indicated that 2007 is likely to be the fifth warmest on record.
Since the start of the 20th century, the global average surface temperature has risen by 0.74°C. But this rise has not been continuous. The linear warming trend over the last 50 years (0.13°C per decade) is nearly twice that for the last 100 years.
According to the Intergovernmental Panel on Climate Change’s 4th Assessment (Synthesis) Report, 2007, “warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.”
2007 global temperatures have been averaged separately for both hemispheres. Surface temperatures for the northern hemisphere are likely to be the second warmest on record, at 0.63°C above the 30-year mean (1961-90) of 14.6°C/58.3°F. The southern hemisphere temperature is 0.20°C higher than the 30-year average of 13.4°C/56.1°F, making it the ninth warmest in the instrumental record since 1850.
January 2007 was the warmest January in the global average temperature record at 12.7°C/54.9°F, compared to the 1961-1990 January long-term average of 12.1°C/53.8°F.
Regional temperature anomalies
2007 started with record breaking temperature anomalies throughout the world. In parts of Europe, winter and spring ranked amongst the warmest ever recorded, with anomalies of more than 4°C above the long-term monthly averages for January and April.
Extreme high temperatures occurred in much of Western Australia from early January to early March, with February temperatures more than 5°C above average.
Two extreme heat waves affected south-eastern Europe in June and July, breaking previous records with daily maximum temperatures exceeding 40°C/104°F in some locations, including up to 45°C/113°F in Bulgaria. Dozens of people died and fire-fighters battled blazes devastating thousands of hectares of land. A severe heat wave occurred across the southern United States of America during much of August with more than 50 deaths attributed to excessive heat. August to September 2007 was extremely warm in parts of Japan, setting a new national record of absolute maximum temperature of 40.9°/105.6°F on 16 August.
In contrast, Australia recorded its coldest ever June with the mean temperature dropping to 1.5°C below normal. South America experienced an unusually cold winter (June-August), bringing winds, blizzards and rare snowfall to various provinces with temperatures falling to -22°C/-7.6°F in Argentina and -18°C/-0.4°F in Chile in early July.
Prolonged drought
Across North America, severe to extreme drought was present across large parts of the western U.S. and Upper Midwest, including southern Ontario/Canada, for much of 2007. More than three-quarters of the Southeast U.S. was in drought from mid-summer into December, but heavy rainfall led to an end of drought in the southern Plains.
In Australia, while conditions were not as severely dry as in 2006, long term drought meant water resources remained extremely low in many areas. Below average rainfall over the densely populated and agricultural regions resulted in significant crop and stock losses, as well as water restrictions in most major cities.
China experienced its worst drought in a decade, affecting nearly 40 million hectares of farmland. Tens of millions of people suffered from water restrictions.
Flooding and intense storms
Flooding affected many African countries in 2007. In February, Mozambique experienced its worst flooding in six years, killing dozens, destroying thousands of homes and flooding 80,000 hectares of crops in the Zambezi valley.
In Sudan, torrential rains caused flash floods in many areas in June/July, affecting over 410,000 people, including 200,000 left homeless. The strong southwesterly monsoon resulted in one of the heaviest July-September rainfall periods, triggering widespread flash floods affecting several countries in West Africa, Central Africa and parts of the Greater Horn of Africa. Some 1.5 million people were affected and hundreds of thousands homes destroyed.
In Bolivia, flooding in January-February affected nearly 200,000 people and 70,000 hectares of cropland. Strong storms brought heavy rain that caused extreme flooding in the littoral region of Argentina in late March/early April. In early May, Uruguay was hit by its worst flooding since 1959, with heavy rain producing floods that affected more than 110,000 people and severely damaged crops and buildings. Triggered by storms, massive flooding in Mexico in early November destroyed the homes of half a million people and seriously affected the country’s oil industry.
In Indonesia, massive flooding on Java in early February killed dozens and covered half of the city of Jakarta by up to 3.7 metres of water. Heavy rains in June ravaged areas across southern China, with flooding and landslides affecting over 13.5 million people and killing more than 120. Monsoon-related extreme rainfall events caused the worst flooding in years in parts of South Asia. About 25 million people were affected in the region, especially in India, Pakistan, Bangladesh and Nepal. Thousands lost their lives. However, rainfall during the Indian summer monsoon season (June-September) for India was, generally, near normal (105% of the long-term average), but with marked differences in the distribution of rainfall in space and time.
A powerful storm system, Kyrill, affected much of northern Europe during 17-18 January 2007 with torrential rains and winds gusting up to 170km/h. There were at least 47 deaths across the region, with disruptions in electric supply affecting tens of thousands during the storm.
England and Wales recorded its wettest May-July period since records began in 1766, receiving 406 mm of rain compared to the previous record of 349 mm in 1789. Extensive flooding in the region killed nine and caused more than US$6 billion in damages.
Development of La Niña
The brief El Niño event of late 2006 quickly dissipated in January 2007, and La Niña conditions became well established across the central and eastern Equatorial Pacific in the latter half of 2007.
In addition to La Niña, unusual sea surface temperature patterns with cooler than normal values across the north of Australia to the Indian Ocean, and warmer than normal values in the Western Indian Ocean, were recorded. These are believed to have modified the usual La Niña impacts in certain regions around the world.
The current La Niña is expected to continue into the first quarter of 2008 at least.
Devastating tropical cyclones
Twenty-four named tropical storms developed in the North-West Pacific during 2007, below the annual average of 27. Fourteen storms were classified as typhoons, equalling the annual average. Tropical cyclones affected millions in south-east Asia, with typhoons Pabuk, Krosa, Lekima and tropical storms like Peipah among the severest.
During the 2007 Atlantic Hurricane season, 14 named storms occurred, compared to the annual average of 12, with 6 being classified as hurricanes, equalling the average. For the first time since 1886, two category 5 hurricanes (Dean and Felix) made landfall in the same season.
In February, due to tropical cyclone Gamède, a new worldwide rainfall record was set in French La Reunion with 3,929 mm measured within three days.
In June, cyclone Gonu made landfall in Oman, affecting more than 20,000 people and killing 50, before reaching the Islamic Republic of Iran. There is no record of a tropical cyclone hitting Iran since 1945.
On 15 November, tropical cyclone Sidr made landfall in Bangladesh, generating winds of up to 240 km/h and torrential rains. More than 8.5 million people were affected and over 3,000 died. Nearly 1.5 million houses were damaged or destroyed. Often hit by cyclones, Bangladesh has developed a network of cyclone shelters and a storm early-warning system, which significantly reduced casualties.
Australia’s 2006/2007 tropical season was unusually quiet, with only five tropical cyclones recorded, equalling the lowest number observed since at least 1943-44.
Relatively small Antarctic ozone hole
The 2007 Antarctic ozone hole was relatively small due to mild stratosphere winter temperatures. Since 1998, only the 2002 and 2004 ozone holes were smaller. In 2007, the ozone hole reached a maximum of 25 million square kms in mid-September, compared to 29 million square kms in the record years of 2000 and 2006. The ozone mass deficit reached 28 megatonnes on 23 September, compared to more than 40 megatonnes in the record year of 2006.
Record-low Arctic sea ice extent opened the Northwest Passage
Following the Arctic sea ice melt season, which ends annually in September at the end of the northern summer, the average “sea ice extent” was 4.28 million square kms, the lowest on record. The “sea ice extent” at September 2007 was 39% below the long-term 1979-2000 average, and 23% below the previous record set just two years ago in September 2005.For the first time in recorded history, the disappearance of ice across parts of the Arctic opened the Canadian Northwest Passage for about five weeks starting 11 August. Nearly 100 voyages in normally ice-blocked waters sailed without the threat of ice. The September rate of sea ice decline since 1979 is now approximately 10% per decade, or 72,000 square kms per year.
Sea level rise continues
The sea level continued to rise at rates substantially above the average for the 20th century of about 1.7 mm per year. Measurements show that the 2007 global averaged sea level is about 20 cm higher than the 1870 estimate. Modern satellite measurements show that since 1993 global averaged sea level has been rising at about 3 mm per year.
Global 10 Warmest Years Mean Global temperature (°C) (anomaly with respect to 1961-1990)
1998 0.52
2005 0.48
2003 0.46
2002 0.46
2004 0.43
2006 0.42
2007(Jan-Nov) 0.41
2001 0.40
1997 0.36
1995 0.28
UK 10 Warmest Years Mean UK Temperature (°C) (anomaly with respect to 1971-2000)
2006 +1.15
2007 (Jan to 10th Dec) + 1.10
2003 + 0.92
2004 + 0.89
2002 + 0.89
2005 + 0.87
1990 + 0.83
1997 + 0.82
1949 + 0.80
1999 + 0.78
Adapted from materials provided by World Meteorological Organization.

Fausto Intilla

www.oloscience.com

'Magma P.I.' Unearths Clues To How Earth's Crust Was Sculpted

Source:

http://www.sciencedaily.com/releases/2007/12/071203135731.htm

ScienceDaily (Dec. 14, 2007) — About a decade ago, Johns Hopkins University geologist Bruce Marsh challenged the century-old concept that the Earth's outer layer formed when crystal-free molten rock called magma oozed to the surface from giant subterranean chambers hidden beneath volcanoes.

Marsh's theory -- that the deep-seated plumbing underneath volcanoes is actually made up of an extensive system of smaller sheet-like chambers vertically interconnected with each other and transporting a crystal-laden "magmatic mush" to the surface -- has become far more widely accepted. This sort of system, known as a "magmatic mush column," is thought to exist beneath all of the world's major volcanic centers.
Now, Marsh -- using the windswept McMurdo Dry Valleys of Antarctica as his "walk in" laboratory -- posits that these channels did more than simply transport or supply magma and crystals to form the Earth's surface: As the magma pushed up through the earth, the pressure fractured the crust in such a way that it provided a sort of "template," guiding later erosion in sculpting a series of valleys and mountain ranges there.
Marsh described his latest findings to fellow scientists at a recent meeting of the American Geological Society.
"As the magma made its way to the surface, the pressure broke the crust up into pieces," Marsh says. "That fracturing reflected a pattern of stress in the same way that a windshield put under pressure will eventually fracture and the pattern of the broken glass would reflect where the stress was originally applied.
"Magma then seeped in," he says, "and 'welded' the fractures, sealing them temporarily until erosion -- in the form of snow, rain, ice and wind -- went to work on these weaknesses, carving out valleys, mountains and other landforms that we see there today and marking where the solidified magma originally was."
Marsh said that, in Antarctica, both of these functions date back at least 180 million years to the time when the continents split apart. He points out that this observation brings together the usually disparate study of deep-seated magmatic processes and land-surface evolution.
"It's one of those situations where, usually, never the twain shall meet, but they do in this case," the earth scientist said. "Having recognized evidence in this critical process in the McMurdo Dry Valleys is important because it may allow us to recognize it in other areas where the geologic record is scantier and less complete."
The Dry Valleys makes an ideal place to study these systems because it was eroded into its present form millions of years ago and has, unlike the rest of Earth's surface, undergone very little subsequent erosion. His colleagues George Denton of the University of Maine and David Marchant of Boston University call this region "a relic landscape," because it is the only known place on Earth that looks almost exactly as it did millions of years ago.
"The delicacy of the landscape in the Dry Valleys has preserved for us an unusually rich collection of geologic evidence of the processes that formed this terrain," Marsh said.
For more than a quarter of a century, Marsh -- who could be thought of by fans of 1980s detective television shows as sort of a "Magma P.I." -- has been working to understand the deep underground systems that bring magma to the Earth's surface. In 1993, he found the Dry Valleys, a walk-in "museum" that he calls "the one place on earth where the plumbing system is exposed in this way."
"You can stand on shelves of solidified lava that were deposited by magmatic activity 180 million years ago," he said. "It's awe inspiring."
Adapted from materials provided by Johns Hopkins University.

Fausto Intilla

www.oloscience.com

NASA Spacecraft Make New Discoveries About Northern Lights

Source:

http://www.sciencedaily.com/releases/2007/12/071211233038.htm

ScienceDaily (Dec. 12, 2007) — A fleet of NASA spacecraft, launched less than eight months ago, has made three important discoveries about spectacular eruptions of Northern Lights called "substorms" and the source of their power.

NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission observed the dynamics of a rapidly developing substorm, confirmed the existence of giant magnetic ropes and witnessed small explosions in the outskirts of Earth's magnetic field. The findings will be presented at the annual meeting of the American Geophysical Union in San Francisco in December.
The discoveries began on March 23, when a substorm erupted over Alaska and Canada, producing vivid auroras for more than two hours. A network of ground cameras organized to support THEMIS photographed the display from below while the satellites measured particles and fields from above.
"The substorm behaved quite unexpectedly," says Vassilis Angelopoulos, the mission's principal investigator at the University of California, Los Angeles. "The auroras surged westward twice as fast as anyone thought possible, crossing 15 degrees of longitude in less than one minute. The storm traversed an entire polar time zone, or 400 miles, in 60 seconds flat."
Photographs taken by ground cameras and NASA's Polar satellite (also supporting the THEMIS mission) revealed a series of staccato outbursts each lasting about 10 minutes. Angelopoulos said that some of the bursts died out while others reinforced each other and went on to become major onsets.
Angelopoulos was quite impressed with the substorm's power and he estimated the total energy of the two-hour event at five hundred thousand billion Joules. That's equivalent to the energy of one magnitude 5.5 earthquake . Where does all that energy come from" THEMIS may have found the answer.
"The satellites have found evidence of magnetic ropes connecting Earth's upper atmosphere directly to the sun," said David Sibeck, project scientist for the mission at NASA's Goddard Space Flight Center, Greenbelt, Md. "We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras."
A magnetic rope is a twisted bundle of magnetic fields organized much like the twisted hemp of a mariner's rope. Spacecraft have detected hints of these ropes before, but a single spacecraft was insufficient to map their 3D structure. THEMIS' five identical micro-satellites were able to perform the feat.
"THEMIS encountered its first magnetic rope on May 20," said Sibeck. "It was very large, about as wide as Earth, and located approximately 40,000 miles (70,000 km) above Earth's surface in a region called the magnetopause." The magnetopause is where the solar wind and Earth's magnetic field meet and push against one another like sumo wrestlers locked in combat. There, the rope formed and unraveled in just a few minutes, providing a brief but significant conduit for solar wind energy.
THEMIS also has observed a number of small explosions in Earth's magnetic bow shock. "The bow shock is like the bow wave in front of a boat," explained Sibeck. "It is where the solar wind first feels the effects of Earth's magnetic field. Sometimes a burst of electrical current within the solar wind will hit the bow shock and--Bang! We get an explosion."
The THEMIS satellites are equipped with instruments that measure ions, electrons and electromagnetic radiation in space. The satellites will line up along the sun-Earth line next February to perform their key measurements. Researchers expect to observe, for the first time, the origin of substorm onsets in space and learn more about their evolution. Scientists from the US, Canada, Western Europe, Russia and Japan are contributing to the scientific investigation over the next two years.
THEMIS is the fifth medium-class mission under NASA's Explorer Program, which provides frequent flight opportunities for world-class scientific investigations within the heliophysics and astrophysics science areas.
The Explorer Program Office at Goddard manages the NASA-funded THEMIS mission. The University of California, Berkeley's Space Sciences Laboratory is responsible for project management, science and ground-based instruments, mission integration and post launch operations. ATK (formerly Swales Aerospace), Beltsville, Md., built the THEMIS probes.
Adapted from materials provided by NASA/Goddard Space Flight Center.

Fausto Intilla

www.oloscience.com

Greenland Melt Accelerating, According To Climate Scientist

Source:

http://www.sciencedaily.com/releases/2007/12/071211233433.htm

ScienceDaily (Dec. 12, 2007) — 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, according to 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 Earth's atmosphere, according to 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 Program's 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 Greenland's 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.
Although Greenland has been thickening at higher elevations due to increases in snowfall, the gain is more than offset by an accelerating mass loss, primarily from rapidly thinning and accelerating outlet glaciers, Steffen said. "The amount of ice lost by Greenland over the last year is the equivalent of two times all the ice in the Alps, or a layer of water more than one-half mile deep covering Washington, D.C."
The Jacobshavn Glacier on the west coast of the ice sheet, a major Greenland outlet glacier draining roughly 8 percent of the ice sheet, has sped up nearly twofold in the last decade, he said. Nearby glaciers showed an increase in flow velocities of up to 50 percent during the summer melt period as a result of melt water draining to the ice-sheet bed, he said.
"The more lubrication there is under the ice, the faster that ice moves to the coast," said Steffen. "Those glaciers with floating ice 'tongues' also will increase in iceberg production."
Greenland is about one-fourth the size of the United States, and about 80 percent of its surface area is covered by the massive ice sheet. Greenland hosts about one-twentieth of the world's ice -- the equivalent of about 21 feet of global sea rise. The current contribution of Greenland ice melt to global sea levels is about 0.5 millimeters annually.
The most sensitive regions for future, rapid change in Greenland's ice volume are dynamic outlet glaciers like Jacobshavn, which has a deep channel reaching far inland, he said. "Inclusion of the dynamic processes of these glaciers in models will likely demonstrate that the 2007 Intergovernmental Panel on Climate Change assessment underestimated sea-level projections for the end of the 21st century," Steffen said.
Helicopter surveys indicate there has been an increase in cylindrical, vertical shafts in Greenland's ice known as moulins, which drain melt water from surface ponds down to bedrock, he said. Moulins, which resemble huge tunnels in the ice and may run vertically for several hundred feet, switch back and forth from vertical to horizontal as they descend toward the bottom of the ice sheet, he said.
"These melt-water drains seem to allow the ice sheet to respond more rapidly than expected to temperature spikes at the beginning of the annual warm season," Steffen said. "In recent years the melting has begun earlier than normal."
Steffen and his team have been using a rotating laser and a sophisticated digital camera and high-definition camera system provided by NASA's Jet Propulsion Laboratory to map the volume and geometry of moulins on the Greenland ice sheet to a depth of more than 1,500 feet. "We know the number of moulins is increasing," said Steffen. "The bigger question is how much water is reaching the bed of the ice sheet, and how quickly it gets there."
Steffen said the ice loss trend in Greenland is somewhat similar to the trend of Arctic sea ice in recent decades. In October, CU-Boulder's National Snow and Ice Data Center reported the 2007 Arctic sea-ice extent had plummeted to the lowest levels since satellite measurements began in 1979 and was 39 percent below the long-term average tracked from 1979 to 2007.
CIRES is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration. For more information on Steffen's research, visit the Web site at: http://cires.colorado.edu/science/groups/steffen/.
Adapted from materials provided by University of Colorado at Boulder.

Fausto Intilla

www.oloscience.com

In Search For Water On Mars, Clues From Antarctica

Source:

http://www.sciencedaily.com/releases/2007/12/071210094326.htm

ScienceDaily (Dec. 11, 2007) — Scientists have gathered more evidence that suggests flowing water on Mars -- by comparing images of the red planet to an otherworldly landscape on Earth.

In recent years, scientists have examined images of several sites on Mars where water appears to have flowed to the surface and left behind a trail of sediment. Those sites closely resemble places where water flows today in the McMurdo Dry Valleys in Antarctica, the new study has found.
The new study bolsters the notion that liquid water could be flowing beneath the surface of Mars. And since bacteria thrive in the liquid water flowing in the Dry Valleys, the find suggests that bacterial life could possibly exist on Mars as well.
Researchers have used the Dry Valleys as an analogy for Mars for 30 years, explained Berry Lyons, professor of earth sciences and director of the Byrd Polar Research Center at Ohio State University.
Lyons is lead principal investigator for the National Science Foundation's Long Term Ecological Research (LTER) Network, a collaboration of more than 1,800 scientists who study the ecology of sites around the world.
One of the LTER sites is in the Dry Valleys, a polar desert in Antarctica with year-round saltwater flowing beneath the surface. With temperatures that dip as low as negative 85 degrees Fahrenheit, it's as cold as the Martian equator, and its iron-rich soil gives it a similar red color.
“If you looked at pictures of both landscapes side by side, you couldn't tell them apart,” Lyons said.
In the new study, LTER scientists did just that -- they compared images of water flows in the Dry Valleys to images of gullies on Mars that show possible evidence of recent water flow.
Team member Peter Doran of the University of Illinois at Chicago presented the results Tuesday, December 11, 2007, at the American Geophysical Union meeting at San Francisco .
The scientists' conclusion: the Martian sites closely resemble sites in the Dry Valleys where water has seeped to the surface.
The water in the Dry Valleys can be very salty -- it's full of calcium chloride, the same kind of salt we sprinkle on roadways to melt ice. That's why the water doesn't freeze. Natural springs form from melted ground ice or buried glacier ice, and the saltwater percolates to the surface.
“Even in the dead of winter, there are locations with salty water in the Dry Valleys ,” Lyons said. “Two months a year, we even have lakes of liquid water covered in ice.”
But after the water reaches the surface, it evaporates, leaving behind salt and sediment.
The same thing would happen on Mars, he added.
Because the suspected sediment sites on Mars closely resemble known sediment sites in the Dry Valleys, Lyons and his colleagues think that liquid saltwater is likely flowing beneath the Martian surface.
Lyons, who has led many expeditions to Antarctica, said that his team will continue to compare what they learn on Earth to any new evidence of water uncovered on Mars.
As they walk across the Dry Valleys, they can't help but compare the two.
“There's just something about that landscape, about being so far from civilization, that makes you think about other worlds,” he said.
Adapted from materials provided by Ohio State University.

Fausto Intilla

www.oloscience.com

Age-old Mystery Of Missing Chemicals From Earth's Mantle May Be Solved

Source:

http://www.sciencedaily.com/releases/2007/12/071205131152.htm

ScienceDaily (Dec. 9, 2007) — Observations about the early formation of Earth may answer an age-old question about why the planet's mantle is missing some of the matter that should be present, according to UBC geophysicist John Hernlund.

Earth is made from chondrite, very primitive rocks of meteorites that date from the earliest time of the solar system before the Earth was formed. However, scientists have been puzzled why the composition of Earth's mantle and core differed from that of chondrite.
Hernlund's findings suggest that an ancient magma ocean swirled beneath the Earth's surface and would account for the discrepancy.
"As the thick melted rock cooled and crystallized, the solids that resulted had a different composition than the melt," explains Hernlund, a post-doctoral fellow at UBC Earth and Ocean Sciences.
"The melt held onto some of the elements. This would be where the missing elements of chondrite are stored."
He says this layer of molten rock would have been around 1,000 km thick and 2,900 km beneath the surface."
Published in the journal Nature, Hernlund's study explores the melting and crystallization processes that have controlled the composition of the Earth's interior over geological time. Co-authors are Stéphane Labrosse, Ecole Normale Superieure de Lyon and Nicolas Coltice, Université de Lyon.
The centre of Earth is a fiery core of melted heavy metals, mostly iron. This represents 30 per cent while the remaining 70 per cent is the outer mantle of solid rock.
Traditional views hold that a shallow ocean of melted rock (magma) existed 1,000 km below the Earth's surface, but it was short lived and gone by 10 million years after the formation of Earth.
In contrast, Hernlund's evolutionary model predicts that during Earth's hotter past shortly after its formation 4.5 billion years ago, at least one-third of the mantle closest to the core was also melted.
The partially molten patches now observed at the base of the Earth's mantle could be the remnants of such a deep magma ocean, says Hernlund.
Adapted from materials provided by University of British Columbia.

Fausto Intilla

www.oloscience.com

Helium Isotopes Point To New Sources Of Geothermal Energy

Source:

http://www.sciencedaily.com/releases/2007/11/071129183725.htm

ScienceDaily (Dec. 3, 2007) — With fossil fuel sources depleting and global warming on the rise, exploring alternative means of power for humans is a necessary reality. Now, looking to the sky, relying on the wind or harnessing water power are not the only remaining options. Deep within Earth is an untapped source of energy: geothermal energy.

It has been estimated that within the continental United States, there is a sizable resource of accessible geothermal energy -- about 3,000 times the current annual U.S. consumption.
Two important reasons this storehouse of energy has not been tapped is that locating the specific energy hot spots is difficult and expensive.
"Since many geothermal resources are hidden, that is, they do not show any clear indications of their presence at the surface, locating them by just using observations made at the surface is difficult," explains Matthijs van Soest, associate research professional at the Noble Gas Geochemistry and Geochronology Laboratory within the School of Earth and Space Exploration at Arizona State University.
"Often when people thought there might be a geothermal resource below the surface the only way to determine if their assumption was correct was drilling and drilling is extremely expensive," he says.
Now, research by van Soest and B. Mack Kennedy at Lawrence Berkeley National Laboratory reveals that geothermal exploration doesn't have to be high-priced.
And it doesn't even have to require drilling.
In a survey of the northern Basin and Range province of the western United States, geochemists Mack Kennedy of the Department of Energy's Lawrence Berkeley National Laboratory and Matthijs van Soest of Arizona State University have discovered a new tool for identifying potential geothermal energy resources.
Currently, most developed geothermal energy comes from regions of volcanic activity, such as The Geysers in Northern California. The potential resources identified by Kennedy and van Soest arise not from volcanism but from the flow of surface fluids through deep fractures that penetrate the earth's lower crust, in regions far from current or recent volcanic activity.
"A good geothermal energy source has three basic requirements: a high thermal gradient — which means accessible hot rock — plus a rechargeable reservoir fluid, usually water, and finally, deep permeable pathways for the fluid to circulate through the hot rock," says Kennedy, a staff scientist in Berkeley Lab's Earth Sciences Division. "We believe we have found a way to map and quantify zones of permeability deep in the lower crust that result not from volcanic activity but from tectonic activity, the movement of pieces of the Earth's crust."
Kennedy and van Soest made their discovery by comparing the ratios of helium isotopes in samples gathered from wells, surface springs, and vents across the northern Basin and Range. Helium-three, whose nucleus has just one neutron, is made only in stars, and Earth's mantle retains a high proportion of primordial helium-three (compared to the minuscule amount found in air) left over from the formation of the solar system.
Earth's crust, on the other hand, is rich in radioactive elements like uranium and thorium that decay by emitting alpha particles, which are helium-four nuclei. Thus a high ratio of helium-three to helium-four in a fluid sample indicates that much of the fluid came from the mantle.
High helium ratios are common in active volcanic regions, where mantle fluids intrude through the ductile boundary of the lower crust. But when Kennedy and van Soest found high ratios in places far from volcanism, they knew that mantle fluids must be penetrating the ductile boundary by other means.
The geology of the region was the clue. The Basin and Range is characterized by mountain ranges that mostly run north and south, separated by broad, relatively flat-floored valleys (basins), which are blocks of crust that have sunk and become filled with sediment eroded from the uplifted mountains. The alternating basin and range topography is the result of crustal spreading by east to west extension, which has occurred over the past approximately 30 million years. The Earth's crust in the Basin and Range is some of the thinnest in the world, resulting in unusually high thermal gradients.
The faces of mountain blocks in the Basin and Range clearly exhibit the normal faults that result as the blocks are pulled apart by the extension of the crust. Normal faults form high-angle pathways deep down into the brittle upper crust. But as the fault plane approaches the ductile lower crust, changes in the density and viscosity of the rock refract the principle stress acting on the fault, deflecting the fault plane, which becomes more horizontal. It is from these deep, horizontally-trending faults that Kennedy thinks permeable passageways may emanate, penetrating the ductile boundary into the mantle.
One of the most seismically active areas in the Basin and Range occurs in what is called the central Nevada seismic belt. The researchers' detailed studies in this area, notably at the Dixie Valley thermal system next to the Stillwater range, established that the highest helium ratios were restricted to fluids emerging from the Stillwater range-front fault system.
The northern Basin and Range, which Kennedy and van Soest surveyed on behalf of DOE's Office of Basic Energy Sciences and Office of Geothermal Technologies, includes parts of California, Nevada, Oregon, Idaho, and Utah. In their survey the researchers mapped the steady progression from low helium ratios in the east to high ratios in the west. The distribution of the increasing ratios corresponds remarkably with an increase in the rate and a change in the direction of crustal extension, which shifts from an east to west trend across the Basin and Range to a northwest trend.
This change in rate and direction reflects the added shear strain induced by the northward movement of the Pacific Plate past the North American Plate. Kennedy and van Soest believe that the added component of shear strain and increasing extension rate tear open fluid pathways through the ductile lower crust, into the mantle. The high helium isotope ratios they found, indicating potential new sources of geothermal energy, were superimposed upon the general background trend: anomalously high ratios map zones of higher than average permeability.
"We have never seen such a clear correlation of surface geochemical signals with tectonic activity, nor have we ever been able to quantify deep permeability from surface measurements of any kind," says Kennedy. The samples they collected on the surface gave the researchers a window into the structure of the rocks far below, with no need to drill.
With the urgent need to find energy sources that are renewable and don't emit greenhouse gases, geothermal energy is ideal — "the best renewable energy source besides the sun," Kennedy says. Accessible geothermal energy in the United States, excluding Alaska and Hawaii, has been estimated at 9 x 1016 (90 quadrillion) kilowatt-hours, 3,000 times more than the country's total annual energy consumption. Determining helium ratios from surface measurements is a practical way to locate some of the most promising new resources.
Journal reference: "Flow of Mantle Fluids Through the Ductile Lower Crust: Helium Isotope Trends," B. Mack Kennedy and Matthijs C. van Soest, Science, 30 November 2007 .
Adapted from materials provided by DOE/Lawrence Berkeley National Laboratory.

Fausto Intilla

www.oloscience.com