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Lakes A Major Source Of Prehistoric Methane
Photo by Sergey Zimov
UAF researcher Katey Walter lights a pocket of methane on a thermokarst lake in Siberia in March of 2007. Igniting the gas is a way to demonstrate, in the field, that it contains methane. Methane bubbling from arctic lakes could have been responsible for up to 87 percent of that methane spike, said UAF researcher Katey Walter, lead author of a report printed in the Oct. 26 issue of Science magazine. The findings could help researchers understand how current warming might affect atmospheric levels of methane, a gas that is thought to contribute to climate change. "It tells us that this isn't just something that is ongoing now. It would have been a positive feedback to climate warming then, as it is today," said Walter. "We estimate that as much as 10 times the amount of methane that is currently in the atmosphere will come out of these lakes according tomafrost thaws in the future. The timing of this emission is uncertain, but likely we are talking about a time frame of hundreds to thousands of years, if climate warming continues as projected." Ice cores from Greenland and Antarctica have shown that during the early Holocene Period--about 14,000 to 11,500 years ago--the levels of methane in the atmosphere rose significantly, Walter said. "They observed that an unidentified northern source (of methane) appeared during that time."........ Human Migration From Asia To Americas
Image courtesy Ripan Mahli
Map showing migration of humans from Asia to the Americas. A team of 21 researchers, led by Ripan Malhi, a geneticist in the department of anthropology at the University of Illinois, has a new set of ideas. One is a striking hypothesis that seems to map the peopling process during the pioneering phase and well beyond, and at the same time show that there was much more genetic diversity in the founder population than was previously thought. The team's findings are published in a recent issue of the Public Library of Science in an article titled, "Beringian Standstill and Spread of Native American Founders". "Our phylogeographic analysis of a new mitochondrial genome dataset allows us to draw several conclusions," the authors wrote. "First, before spreading across the Americas, the ancestral population paused in Beringia long enough for specific mutations to accumulate that separate the New World founder lineages from their Asian sister-clades." (A clade is a group of mitochondrial DNAs (mtDNAs ) that share a recent common ancestor, Malhi said. Sister-clades would include two groups of mtDNAs that each share a recent common ancestor and the common ancestor for each clade is closely related.)......... Earth from Space: Birth of an iceberg
The animation highlights the movement in the area between September 2006 and October 2007. The Pine Island Glacier is visible stretching from the right of the image to the centre. The tongue of Pine Island is shown moving inland between September 2006 and March 2007. Between April and May 2007, the detached iceberg in front of Pine Island moves significantly. Also in May 2007, a crack in Pine Island becomes visible. By October, the new iceberg has completely broken away. Several different processes can cause an iceberg to form, or 'calve', such as action from winds and waves, the ice shelf grows too large to support part of itself or a collision with an older iceberg. Since Pine Island Glacier was already floating before it calved, it will not cause any rise in the world sea level. Iceberg calving like this occurs in Antarctica each year and is part of the natural lifecycle of the ice sheet. A 34-year long study of the glacier has shown that a large iceberg breaks off roughly every 5-10 years. The last event was in 2001......... Earth Impact Database
Satellite methods for monitoring volcanic activity
Research projects on deformations of the earth crust, conducted in this region between 1992 and 2000 by a North American team, had led to the detection of a long wavelength signal over the areas topography, extracted from analysis of data collected by the European Space Agency (ESA) satellite ERS-1. This deformation would correspond to crustal inflation affecting the whole Lastarria-Cordon del Azufre complex. Eventhough this volcano is not considered as active, as the last eruption dates back 9000 years, such inflation could express an underlying activity correlation to the dynamics of a functioning magma chamber......... Earthquake Experts Turn to History for Guidance
Damage in Jerusalem's Old City following a July 11, 1927, earthquake. One of the first earthquakes on the Dead Sea Fault to be recorded by modern seismographic techniques, it reached 6.2 on the Richter scale. The epicenter was in the northern part of the Dead Sea. Photo credit: American Colony Hotel, American Colony Collection.
A major quake of magnitude seven on the Richter scale in the politically-fragile region of the Middle East could have dire consequences for precious holy sites and even world peace, says Tel Aviv University geologist Dr. Shmulik Marco. In light of this imminent danger, Marco, from the school's Department of Geophysics and Planetary Sciences, has taken an historical approach to earthquake forecasting by using ancient records from the Vatican and other religious sources in his assessment. The past holds the key to the future, he says. "All of us in the region should be worried," explains Marco, who dedicates his career to piecing together ancient clues. Based on the translations of hundreds of documents -- some of the originals of which he assumes reside in Vatican vaults -- Marco has helped determine that a series of devastating earthquakes have hit the Holy Land over the last two thousand years. The major ones were recorded along the Jordan Valley in the years 31 B.C.E., 363 C.E., 749 C.E., and 1033 C.E. "So roughly," warns Marco, "we are talking about an interval of every 400 years. If we follow the patterns of nature, a major quake should be expected any time because almost a whole millennium has passed since the last strong earthquake of 1033"......... Majority of Americans want local action on global warming
City and local leaders are critical players in the effort to reduce global warming, and its clear that their constituents want action, said Anthony Leiserowitz, director of Yale Project on Climate Change, one of the sponsors of the groundbreaking survey measuring public opinion of local government-led green initiatives. The public is on board and willing to help foot the bill. All thats left to do now is act. As per the survey, 74 percent of Americans would support local regulations requiring all newly constructed homes to be more energy efficient, even if it would increase the initial cost of a new home by roughly $7,500. Seventy-two percent said they would support local subsidies encouraging homeowners to install electricity-generating solar panels on existing homes, even if it would cost households an extra $5 per month in increased property taxes, because of the potential savings in energy and money on utility bills. The survey also observed that:......... Amazon Forest Unexpectedly Resilient to Drought
During the 2005 drought in the Amazon, intact primary forest showed an increase in photosynthetic activity (left image) despite below-average rainfall (right image). Data from NASA's Terra satellite (left) showed areas of higher (green) and lower (red) growth during the peak of the drought (July-Sept.). Data from the Tropical Rainfall Measuring Mission satellite (right) showed areas of severe rainfall reduction due to the drought (red) and few areas with above normal rainfall (blue). Credit: Kamel Didan, University of Arizona Terrestrial Biophysics and Remote Sensing Lab.
The Amazon drought of 2005 reached its peak just as the region's annual dry season was beginning, from July through September. Eventhough the double whammy of the parched conditions might be expected to slow the growth of the forest's leafy canopy, in much of the drought-stricken areas the canopy became significantly greener -- an indication of increased photosynthetic activity. "Instead of 'hunkering down' during a drought as you might expect, the forest responded positively to drought, at least in the short term," said study author Scott R. Saleska, an assistant professor of ecology and evolutionary biology at the University Of Arizona. "It's a very interesting and surprising response". The new finding contradicts a prominent global climate model that predicts the Amazon forest would begin to "brown down" after just a month of drought. The model also predicts an eventual forest collapse, shifting the ecosystem permanently from a thick, evergreen, broad-leaved forest to a grassy savanna......... Diminished ice leads to Northwest Passage opening
Envisat ASAR image of the McClure Strait in the Canadian Arctic Archipelago, acquired on 31 August 2007. The McClure Strait is the most direct route of the Northwest Passage and has been fully open since early August 2007. The dark gray colour represents the ice-free areas while green represents areas with sea ice. (Credit: ESA)
The average sea ice extent for the month of September was 1.65 million square miles (4.28 million square kilometers), the lowest September on record, shattering the prior record for the month by 23 percent, which was set in 2005. At the end of the melt season, September 2007 sea ice was 39 percent below the long-term average from 1979 to 2000. If ship and aircraft records from before the satellite era are taken into account, sea ice may have fallen by as much as 50 percent from the 1950s. The September rate of sea ice decline since 1979 is now more than 10 percent per decade, said the CU-Boulder research team. NSIDC is part of the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration. Arctic sea ice has long been recognized as a sensitive climate indicator, said CU-Boulder Research Professor Mark Serreze of CIRES and NSIDC. "Computer projections have consistently shown that as global temperatures rise, the sea ice cover will begin to shrink," he said. "While many natural factors have certainly contributed to the overall decline in sea ice, the effects of greenhouse warming are now coming through loud and clear"......... |
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