New study turns up the heat on soot's role in Himalayan warmingDecember 15, 2009Soot from fire in an unventilated fireplace wafts into a home and settles on the surfaces of floors and furniture. But with a quick fix to the chimney flue and some dusting, it bears no impact on a home's long-term environment. A new modeling study from NASA confirms that when tiny air pollution particles we commonly call soot - also known as black carbon - travel along wind currents from densely populated south Asian cities and accumulate over a climate hotspot called the Tibetan Plateau, the result may be anything but inconsequential. In fact, the new research, by NASA's William Lau and collaborators, reinforces with detailed numerical analysis what earlier studies suggest: that soot and dust contribute as much (or more) to atmospheric warming in the Himalayas as greenhouse gases. This warming fuels the melting of glaciers and could threaten fresh water resources in a region that is home to more than a billion people. Lau explored the causes of rapid melting, which occurs primarily in the western Tibetan Plateau, beginning each year in April and extending through early fall. The brisk melting coincides with the time when concentrations of aerosols like soot and dust transported from places like India and Nepal are most dense in the atmosphere. "Over areas of the Himalayas, the rate of warming is more than five times faster than warming globally," said William Lau, head of atmospheric sciences at NASA's Goddard Space Flight Center in Greenbelt, Md. "Based on the differences it's not difficult to conclude that greenhouse gases are not the sole agents of change in this region. There's a localized phenomenon at play." Nicknamed the "Third Pole", the region in fact holds the third largest amount of stored water on the planet beyond the North and South Poles. But since the early 1960s, the acreage covered by Himalayan glaciers has declined by over 20 percent. Some Himalayan glaciers are melting so rapidly, some scientists postulate, that they may vanish by mid-century if trends persist. Climatologists have generally blamed the build-up of greenhouse gases for the retreat, but Lau's work suggests that may not be the complete story. He has produced new evidence suggesting that an "elevated heat pump" process is fueling the loss of ice, driven by airborne dust and soot particles absorbing the sun's heat and warming the local atmosphere and land surface. A related modeling study by Lau and colleagues has been submitted to Environmental Research Letters for publication. A unique landscape plays supporting actor in the melting drama. The Himalayas, which dominate the plateau region, are the source of meltwater for many of Asia's most important rivers-the Ganges and Indus in India, the Brahmaputra in Bangladesh, the Salween through China, Thailand and Burma, the Mekong across Laos, Cambodia and Vietnam, and the Yellow and Yangtze rivers in China. When fossil fuels are burned without enough oxygen to complete combustion, one of the byproducts is black carbon, an aerosol that absorbs solar radiation (Most classes of aerosols typically reflect incoming sunlight, causing a cooling effect). Rising populations in Asia, industrial and agricultural burning, and vehicle exhaust have thickened concentrations of black carbon in the air. Sooty black carbon travels east along wind currents latched to dust - its agent of transport - and become trapped in the air against Himalayan foothills. The particles' dark color absorbs solar radiation, creating a layer of warm air from the surface that rises to higher altitudes above the mountain ranges to become a major catalyst of glacier and snow melt. Building on work by Veerabhardran Ramanathan of the Scripps Institution of Oceanography, San Diego, Calif., Lau and colleagues conducted modeling experiments that simulated the movement of air masses in the region from 2000 to 2007. They also made detailed numerical analyses of how soot particles and other aerosols absorb heat from the sun. "Field campaigns with ground observations are already underway with more planned to test Lau's modeling results," said Hal Maring who manages the Radiation Sciences program at NASA Headquarters in Washington. "But even at this stage we should be compelled to take notice." "Airborne particles have a much shorter atmospheric lifespan than greenhouse gases," continued Maring. "So reducing particle emissions can have much more rapid impact on warming." "The science suggests that we've got to better monitor the flue on our 'rooftop to the world," said Lau. "We need to add another topic to the climate dialogue." NASA/Goddard Space Flight Center |
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| Related Soot Current Events and Soot News Articles Revisiting chicxulub For decades, scientists have accumulated ever-larger datasets that suggest an enormous space rock crashed into the ocean off the Yucatan Peninsula more than 65 million years ago, resulting in the Cretaceous-Paleogene (K-Pg) extinction. Study finds dirty air in California causes millions worth of medical care each year California's dirty air caused more than $193 million in hospital-based medical care from 2005 to 2007 as people sought help for problems such as asthma and pneumonia that are triggered by elevated pollution levels, according to a new RAND Corporation study. Black Carbon a Significant Factor in Melting of Himalayan Glaciers The fact that glaciers in the Himalayan mountains are thinning is not disputed. However, few researchers have attempted to rigorously examine and quantify the causes. Lawrence Berkeley National Laboratory scientist Surabi Menon set out to isolate the impacts of the most commonly blamed culprit-greenhouse gases, such as carbon dioxide-from other particles in the air that may be causing the melting. Engineers explore environmental concerns of nanotechnology As researchers around the world hasten to employ nanotechnology to improve production methods for applications that range from manufacturing materials to creating new pharmaceutical drugs, a separate but equally compelling challenge exists. Advanced engine-control system reduces biodiesel fuel consumption and emissions Researchers from Purdue University and Cummins Inc. have developed an advanced "closed-loop control" approach for preventing diesel engines from emitting greater amounts of smog-causing nitrogen oxides when running on biodiesel fuels. A unique geography -- and soot and dust -- conspire against Himalayan glaciers "So many disparate elements, both natural and man-made, converge in the Himalayas," said William Lau, a climatologist from NASA's Goddard Space Flight Center in Greenbelt, Md. "There's no other place in the world that could produce such a powerful atmospheric heat pump," referring to a new hypothesis he's put forward to explain the rapid retreat of Himalayan glaciers in recent decades. Black carbon deposits on Himalayan ice threaten Earth's 'Third Pole' Black soot deposited on Tibetan glaciers has contributed significantly to the retreat of the world's largest non-polar ice masses, according to new research by scientists from NASA and the Chinese Academy of Sciences. Soot absorbs incoming solar radiation and can speed glacial melting when deposited on snow in sufficient quantities. Munich lab demonstrates diesel truck engine with barely measurable emissions Just three months after the Euro 5 Norm for exhaust emissions went into force for all new car models, researchers at the Technische Universitaet Muenchen (TUM) have demonstrated an engine that is already close to meeting the more stringent Euro 6 emissions standard. Air pollutants from abroad a growing concern, says new report Plumes of harmful air pollutants can be transported across oceans and continents -- from Asia to the United States and from the United States to Europe -- and have a negative impact on air quality far from their original sources, says a new report by the National Research Council. Wildfires set to increase 50% by 2050 The area of forest burnt by wildfires in the United States is set to increase by over 50% by 2050, according to research by climate scientists. More Soot Current Events and Soot News Articles |
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