November 18, 2008, 5:34 AM CT

quicker, easier way to make coal cleaner

DC--Construction of new coal-fired power plants in the United States is in danger of coming to a standstill, partly due to the high cost of the requirement whether existing or anticipated to capture all emissions of carbon dioxide, an important greenhouse gas. But an MIT analysis suggests an intermediate step that could get construction moving again, allowing the nation to fend off growing electricity shortages using our most-abundant, least-expensive fuel while also reducing emissions.

Instead of capturing all of its CO₂ emissions, plants could capture a significant fraction of those emissions with less costly changes in plant design and operation, the MIT analysis shows.

"Our approach 'partial capture' can get CO₂ emissions from coal-burning plants down to emissions levels of natural gas power plants," said Ashleigh Hildebrand, a graduate student in chemical engineering and the Technology and Policy Program. "Policies such as California's Emissions Performance Standards could be met by coal plants using partial capture rather than having to rely solely on natural gas, which is increasingly imported and subject to high and volatile prices".

Hildebrand will present her findings on Nov. 18 at the 9th International Conference on Greenhouse Gas Control Technologies in Washington, DC. Her co-author is Howard J. Herzog, principal research engineer at the MIT Energy Initiative and chair of the conference organizing committee......... Posted by: Tyler      Read more         Source

November 18, 2008, 5:33 AM CT

Burying the greenhouse gas

To prevent global warming, scientists and policymakers are exploring a variety of options to significantly cut the amount of carbon dioxide that reaches the atmosphere. One possible approach involves capturing greenhouse gases such as carbon dioxide at the source -- an electric power plant, for example -- and then injecting them underground.

While theoretically promising, the technique has never been tested in a full-scale industrial operation. But now MIT engineers have come up with a new software tool to determine how much CO2 can be sequestered safely in geological formations.

The work will be reported Nov. 18 at the 9th International Conference on Greenhouse Gas Control Technologies (GHGT-9), to be held Nov. 16-20 in Washington, D.C.

As per the 2007 MIT study, "The Future of Coal," and other sources, capturing CO2 at coal-burning power plants and storing it in deep geological basins will mitigate its negative effects on the atmosphere.

However, injecting too much CO2 could create or enlarge underground faults that may become conduits for CO2 to travel back up to the atmosphere, said Ruben Juanes, assistant professor of civil and environmental engineering (CEE) and one of the authors of the work. "Our model is a simple, effective way to calculate how much CO2 a basin can store safely. It is the first to look at large scales and take into account the effects of flow dynamics on the stored CO2," he said......... Posted by: Tyler      Read more         Source

November 8, 2008, 5:30 PM CT

Resolve long-standing puzzle in climate science

A team led by Livermore researchers has helped reconcile the differences between simulated and observed temperature trends in the tropics.

Using state-of-the-art observational datasets and results from computer model simulations archived at Lawrence Livermore National Laboratory, LLNL scientists and his colleagues from 11 other scientific institutions have refuted a recent claim that simulated temperature trends in the tropics are fundamentally inconsistent with observations. This claim was based on the application of a flawed statistical test and the use of older observational datasets.

Climate model experiments invariably predict that human-caused greenhouse gas increases should lead to more warming in the tropical troposphere (the lowest layer of the atmosphere) than at the tropical land and ocean surface. This predicted "amplification" behavior is in accord with basic theoretical expectations.

Until several years ago, however, most satellite and weather balloon records suggested that the tropical troposphere had warmed substantially less than the surface.

For nearly a decade, this apparent discrepancy between simulations and reality was a major conundrum for climate scientists. The discrepancy was at odds with the overwhelming body of other scientific evidence pointing toward a "discernible human influence" on global climate......... Posted by: Tyler      Read more         Source

November 6, 2008, 8:09 PM CT

Sunlight has more powerful influence on ocean circulation

A study reported in today's issue of Nature disputes a longstanding picture of how ice sheets influence ocean circulation during glacial periods.

The distribution of sunlight, rather than the size of North American ice sheets, is the key variable in changes in the North Atlantic deep-water formation during the last four glacial cycles, as per the article. The new study goes back 425,000 years, as per Lorraine Lisiecki, first author and assistant professor in the Department of Earth Science at the University of California, Santa Barbara.

Lisiecki and her co-authors studied 24 separate locations in the Atlantic by analyzing information from ocean sediment cores. By observing the properties of the shells of tiny marine organisms, called foraminifera, found in these cores, they were able to deduce information about the North Atlantic deep water formation. Researchers can discern historical ocean temperature and circulation patterns through the analysis of the chemical composition of these marine animals.

Previously, researchers relied on a study called "Specmap," performed in 1992, to find out how different parts of the climate system interacted with one another during glacial cycles. Specmap analyzed ocean circulation at only one place in the Atlantic......... Posted by: Tyler      Read more         Source

October 28, 2008, 10:38 PM CT

Arctic sea ice thinning at record rate

The thickness of sea ice in large parts of the Arctic declined by as much as 19% last winter in comparison to the prior five winters, as per data from ESA's Envisat satellite.

Using Envisat radar altimeter data, researchers from the Centre for Polar Observation and Modelling at University College London (UCL) measured sea ice thickness over the Arctic from 2002 to 2008 and observed that it had been fairly constant until the record loss of ice in the summer of 2007.

Uncommonly warm weather conditions were present over the Arctic in 2007, which some researchers have said explain that summer ice loss. However, this summer reached the second-lowest extent ever recorded with cooler weather conditions present.

Dr Katharine Giles of UCL, who led the study, said: "This summer's low ice extent doesn't seem to have been driven by warm weather, so the question is, was last winter's thinning behind it?" .

The research, reported in Geophysical Research Letters, showed that last winter the average thickness of sea ice over the whole Arctic fell by 26 cm (10%) compared with the average thickness of the prior five winters, but sea ice in the western Arctic lost around 49 cm of thickness.

Giles said the extent of sea ice in the Arctic is down to many factors, including warm temperatures, currents and wind, making it important to know how ice thickness is changing as well as the extent of the ice......... Posted by: Tyler      Read more         Source

October 28, 2008, 5:06 AM CT

Neighborhood greenness has long term positive impact on kids' health

In the first study to look at the effect of neighborhood greenness on inner city children's weight over time, scientists from the Indiana University School of Medicine, Indiana University-Purdue University Indianapolis and the University of Washington report that higher neighborhood greenness is linked to slower increases in children's body mass over a two year period, regardless of residential density.

"Prior work, including our own, has provided snap shots in time, and shown that for children in densely populated cities, the greener the neighborhood, the lower the risk of obesity. Our new study of over 3,800 inner city children revealed that living in areas with green space has a long term positive impact on children's weight and thus health," said Gilbert C. Liu, M.D., senior author of the new study which appears in the recent issue of the American Journal of Preventive Medicine Dr. Liu is assistant professor of pediatrics at the IU School of Medicine and a Regenstrief Institute affiliated scientist.

The new study looked at children ages 3 to 18 years whose residence didn't change over 24 consecutive months. Higher neighborhood greenness was linked to slower increases in body mass index over time, regardless of age, race or sex. This slowing of body mass index could correspond with reduced risk of child obesity in the long term. The inner city children in the study were predominantly African-American, poor, and publically insured......... Posted by: Tyler      Read more         Source

October 28, 2008, 5:03 AM CT

Antarctic glaciers for clues to past and future sea level

Researchers from the U.S., U.K. and Australia have teamed up to explore two of the last uncharted regions of Earth, the Aurora and Wilkes Subglacial Basins, immense ice-buried lowlands in Antarctica with a combined area the size of Mexico. The research could show how Earth's climate changed in the past and how future climate change will affect global sea level.

Researchers believe the barely observed Aurora Subglacial Basin, which lies in East Antarctica, could represent the weak underbelly of the East Antarctic Ice Sheet, the largest remaining body of ice on Earth. Until recently the East Antarctic Ice Sheet, which covers the two basins, had been considered a stable ice reservoir unlikely to contribute to rising sea level in the near future.

Limited soundings of the ice upstream of Australia's Casey Station, however, reveal a vast basin with its base lying kilometers below sea level. The basin could make the East Antarctic Ice Sheet more vulnerable in a warming world. Satellite data show that Totten Glacier, which dominates the ice of the Aurora Subglacial Basin, appears to be losing ice at its downstream edge.

The University of Texas at Austin's Jackson School of Geosciences has teamed up with the University of Edinburgh and the Australian Antarctic Division as part of a major International Polar Year project to study this vast area using multiple airborne instruments......... Posted by: Tyler      Read more         Source

October 23, 2008, 9:19 PM CT

China Should Think Outside The Flooding Box

China's farmers and merchants should take advantage of new agricultural and business opportunities that could help mitigate some effects of the annual flooding behind the Three Gorges Dam on the Yangtze River, as per an Ohio State University wetland expert.

The level of water in the reservoir behind the dam will top off at 575 feet above sea level during the coming winter. The reservoir pool, covering abandoned cities, houses and farm fields formerly populated by an estimated 1.5 million people, will extend over 400 square miles - equivalent to the land area of Hong Kong. Then by summer the water level will drop 100 feet, and the cycle of flooding and receding water will repeat every year after that.

The region will become home to an entirely new ecosystem as an unprecedented amount of water covers what used to be dry land.

The Three Gorges Dam is the largest hydro-electric project in the world, intended to combine the generation of clean power with downstream flood control, and enable shipping in China's interior. Critics are concerned that the reservoir will contain factory toxins and raw sewage and that sediment might cause the reservoir level to rise higher than planned, threatening to flood a large city upstream and possibly even send water spilling over the top of the dam......... Posted by: Tyler      Read more         Source

October 8, 2008, 9:51 PM CT

Gas From the Past Gives New Insights

In recent years, public discussion of climate change has included concerns that increased levels of carbon dioxide will contribute to global warming, which in turn may change the circulation in the earth's oceans, with potentially disastrous consequences.

In a paper published recently in the journal Science, scientists presented new data from their analysis of ice core samples and ocean deposits dating as far back as 90,000 years ago and suggest that warming, carbon dioxide levels and ocean currents are tightly inter-related. These findings provide researchers with more data and insights into how these phenomena were connected in the past and may lead to a better understanding of future climate trends.

With support from the National Science Foundation, Jinho Ahn and Edward Brook, both georesearchers at Oregon State University, analyzed 390 ice core samples taken from Antarctic ice at Byrd Station. The samples offered a snap shot of the Earth's atmosphere and climate dating back between 20,000 and 90,000 years. Sections of the samples were carefully crushed, releasing gases from bubbles that were frozen within the ice through the millennia. These ancient gas samples were then analyzed to measure the levels of carbon dioxide contained in each one.

Ahn and Brook then compared the carbon dioxide levels from the ice samples with climate data from Greenland and Antarctica that reflected the approximate temperatures when the gases were trapped and with ocean sediments in Chile and the Iberian Peninsula. Data from the sediments provided the researchers with an understanding of how fast or slow the ocean currents were in the North Atlantic and how well the Southern Ocean was stratified during these same time periods......... Posted by: Tyler      Read more         Source

October 8, 2008, 9:46 PM CT

The Role of Climate Change

Scientists are homing in on the hurricane-prone Gulf of Mexico and Caribbean Sea to assess the likely changes, between now and the middle of the century, in the frequency, intensity, and tracks of these powerful storms. Initial results are expected early next year.

The National Center for Atmospheric Research (NCAR) in Boulder, Colo., working with federal agencies as well as the insurance and energy industries, has launched an intensive study to examine how global warming will influence hurricanes in the next few decades.

The goal of the project is to provide information to coastal communities, offshore drilling operations, and other interests that could be affected by changes in hurricanes.

"This science builds on years of prior investment," said Cliff Jacobs, program director in the National Science Foundation (NSF)'s Division of Atmospheric Sciences, which is funding the project. "The outcome of this research will shed light on the relationship between global warming and hurricanes, and will better inform decisions by government and industry".

The project relies on an innovative combination of global climate and regional weather models, run on one of the world's most powerful supercomputers.

"It's clear from the impacts of recent hurricane activity that we urgently need to learn more about how hurricane intensity and behavior may respond to a warming climate," says NCAR scientist Greg Holland, who is leading the project. "The increasingly dense development along our coastlines and our dependence on oil from the Gulf of Mexico leaves our society dangerously vulnerable to hurricanes"......... Posted by: Tyler      Read more         Source