NASA - National Aeronautics and Space Administration

A media briefing about black carbon's impact on Himalayan glaciers

WASHINGTON -- Soot 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.

For the complete story, click here.

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Background Information on Teleconference Speakers

› William Lau, chief, Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, Md.
› Susan Kaspari, assistant professor, Central Washington University, Ellensburg, Wa.
› Jeffrey Kargel, senior associate research scientist, Dept. of Hydrology and Water Resources, University of Arizona, Tucson
› Brent Holben, principal investigator, AERONET, NASA Goddard Space Flight Center, Greenbelt, Md.

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Images and Multimedia in Support of the News Conference

Presenter: William Lau, NASA Goddard Space Flight Center

› Download presentation slides (PDF)

	Video: Tiny air pollution particles commonly called soot, but also known as black carbon, are in the air and on the move throughout our planet. The Indo-Gangetic plain, one of the most fertile and densely populated areas on Earth, has become a hotspot for emissions of black carbon (shown in purple and white). Winds push thick clouds of black carbon and dust, which absorb heat from sunlight, toward the base of the Himalayas where they accumulate, rise, and drive a "heat pump" that affects the region's climate. Credit: NASA's Scientific Visualization Studio › Watch movie
	Figure 2: Black carbon may drive an atmospheric feedback loop in the Himalayan region called the "elevated heat pump". The hypothesis suggests that black carbon causes the following: A) Warming and moistening of the upper troposphere over the Tibetan Plateau. B) An advance of the rainy season in northern India/Nepal region in May and June. C) Increased convection that spreads from the foothills of the Himalayas to central India that results in an intensification of the Indian monsoon in June and July. D) Subsequent reduction of monsoon rain in central India in July and August. E) Enhanced snowmelt and rapid retreat of glaciers in the region. Credit: William Lau, NASA › Larger image
	Figure 3: Tiny, dark-colored aerosols — specifically black carbon — travel along wind currents from Asian cities and accumulate over the Tibetan Plateau and Himalayan foothills. Seen here as a light brown mass, these brown clouds of soot absorb sunlight, creating a layer of warm air (seen in orange) that rises to higher altitudes, amplifying the melting of glaciers and snow. Credit: NASA/Sally Bensusen › Watch animation
	Figure 4: Data collected by a lidar instrument on NASA's Calipso satellite shows high levels of aerosols accumulating over northern India and the Himalayas foothills against the steep slopes of the Tibetan Plateau during June 21 (upper panel) and June 22 (lower panel). The green, yellow and red color shows low, medium and high aerosol concentrations of aerosols respectively. In the lower panel, some aerosols can be seen over the top of the Himalayas. Credit: William Lau, NASA › Larger image

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Presenter: Susan Kaspari, Central Washington University

› Download presentation slides (PDF)

	Figure 1: Clouds containing a mixture of soot and other aerosol particles are clearly visible looking South from a point near the crest of the Himalayas in Nepal. In contrast, the view to the North is relatively clear. Credit: Susan Kaspari, Central Washington University › Larger image (North) › Larger image (South)
	Figure 2: As shown in the top figure, estimated black carbon emissions in Asia have increased significantly since the 1950s. The lower two figures shows that black carbon concentrations collected from an ice core at Mount Everest, which spans from 1860 to 2000, have increased threefold from 1970 to present relative to pre-1970 levels. In the same core, there has been no notable increase in iron, which is used as a proxy for dust. Credit: Susan Kaspari, University of Washington / Tami Bond, University of Illinois › Larger image
	Figure 3: Large impurity layers, which are deposits of black carbon and dust, are clearly visible on the surface and in crevasse profiles on Mera glacier in Nepal. Black carbon is shown with a black line. Iron (Fe), a proxy for dust, is shown in red. Such impurities reduce the reflectivity of glaciers and likely cause glacier melt. Data Credit: Susan Kaspari, Central Washington University / Photo Credit: Jesse Cunningham, Jesse Cunningham Photography › Larger image

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Presenter: Jeffrey Kargel, University of Arizona

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Figure 1: A satellite image shows debris-covered glacial tongues melting in North Bhutan as blue glacial lakes form in valleys at the base of the tongues. Such melting has been common, especially in the Eastern Himalaya, since the 1950s and 1960s. Credit: ASTER Science Team, NASA › Larger image

Figure 2: Some glaciers in the Mount Everest area are stable, but others are known to be thinning and slowly losing mass along their long debris-covered tongues. Khumbu, the biggest glacier in the upper left quadrant of the image, flows from the Southern slope of Mount Everest and is stable. Imja Glacier, in contrast, is retreating rapidly. Credit: ASTER Science Team, NASA › Larger image (labeled) › Larger image (unlabeled)

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Presenter: Brent Holben, NASA

› Download presentation slides (PDF)

	Figure 1: Lamp-sized instruments called sun-photometers can be used to detect black carbon and dust, though the rugged topography of the Himalayas makes collecting the data challenging. The instruments measure the intensity of light filtering through a given column of atmosphere making it possible to deduce the size, shape, and chemical composition of black carbon and other airborne particles. This instrument, located in central Tibet at Langtang National Park, is part of a network of sun photometers called AERONET. Credit: NASA › Larger image
	Figure 2: Aerosol loading (blue line) is extremely high and increases rapidly from March to May in the Indo-Gangetic Plain. The aerosol type (red line) shows a marked shift between March to May to larger particles, which are indicative of dust, while the black carbon concentration remains largely the same. The available water vapor (green line) increases rapidly until precipitation begins in July with the arrival of the monsoon. Credit: Brent Holben, NASA › Larger image
	Figure 3: Black carbon associates easily with some other types of aerosols particles. In this image, small black soot particles have attached to larger white dust minerals. Above the Indo-Gangetic Plain, dust from the Thar desert often transports black carbon toward the Himalayan foothills. Credit: James Anderson, Arizona State University › Larger image

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Related Links

› New Study Turns Up the Heat on Soot's Role in Himalayan Warming (Feature Story)
› A Unique Geography—And Soot—Conspires Against Himalayan Glaciers
› Soot is Key Player in Himalayan Warming, Looming Water Woes in Asia
› Black Carbon Threatens Earth’s Third Pole