Satellite paints smoggy portrait of the planet

Air pollution, shown in red, moves across the Earth. This image was taken March 23, 2000

By Richard Stenger
CNN

(CNN) -- Watching colossal plumes of smog drift across continents and oceans, a NASA satellite has produced the most comprehensive view ever of air pollution on the planet.

Monitoring carbon monoxide levels in the atmosphere over time, the Terra orbiter demonstrates that pollutants respect no national boundaries.

Forest fires in Africa and South America hurl heavy concentrations of smoke as far as Australia. Factories and fires in Southeast Asia do the same to North America.

"With these new observations you clearly see that air pollution is much more than a local problem. It's a global issue," said John Gille, a Terra researcher with the National Center for Atmospheric Research.

Gille and colleagues unveiled the new Terra images at an American Geophysical Union meeting on Wednesday in Boston. Terra measures carbon monoxide in the troposphere, the layer of the atmosphere between two and three miles above the Earth's surface.

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There, the pollutant interacts with other gases to form smog, which can move higher in the atmosphere and travel great distances or waft downward to the surface, where it can settle into the lungs of humans and animals.

In Terra's color-coded images, bright red areas depict the highest concentrations of carbon monoxide. The red zones wax and wane in hot spots like central Africa, the Amazon, Southeast Asia, and occasionally North America and Europe. In those regions, industries and fires, both natural and manmade, spawn plumes of carbon monoxide that stretch over entire oceans.

Much of the Northern Hemisphere seems gripped with a permanent greenish fog, evidence of a persistent if slightly weaker case of carbon monoxide poisoning.

In North America, the changing blobs of color document the summer smoke of forest fires in the West and the winter trail of fossil fuel emissions in the East.

While Terra cannot discern individual pollution sources, the spacecraft can distinguish air pollution from particular metropolitan areas and forests. About 50 percent of world carbon monoxide emissions come from human activities, NASA researchers said.

By tracking carbon monoxide, a byproduct of the burning of fossil fuels or organic matter such as wood, scientists can indirectly track the movements of related pollutants such as nitrogen oxides.

The flagship of NASA's Earth Observing System, Terra launched in December and began collecting science data in late February.