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Tracking Air Pollution... from Space

September 10 , 2001

NASA's Terra spacecraft is providing scientists the most complete view of global pollution. In this image, red colors represent the highest levels of carbon monoxide (CO), about 450 parts per billion, and blue colors indicate lowest levels of CO, about 50 parts per billion. Terra sees CO in the atmosphere from 2-3 miles above the surface, where it interacts with other gases and forms ozone. (Courtesy: NASA/NCAR/CSA)

NASA's Terra Spacecraft has assembled the first ever complete view of the world's air pollution as it treks around the globe. Terra's new global air pollution monitor, contributed by the Canadian Space Agency, allows scientists to identify the major sources of air pollution and see what happens to it... anywhere on the planet.

Terra is one of the United States' major Earth-observing satellite systems (EOS), designed for the accumulation of data needed to predict future changes in the global environment.

NASA's Terra spacecraft
(Courtesy: NASA/NCAR/CSA)

It takes pictures with digital cameras, about 435 miles (700 km) above the Earth, basically to catch reflected sunlight and released heat on or from the Earth, rather than scanning the global surface by microwaves. Unlike other satellites, Terra travels in a North - South polar orbit.

Through Terra, which launched in December 1999, air pollution is clearly identified as a global problem, with pollution from sources in one region having a dramatic impact on others. Among the greatest impacts observed so far includes the transcontinental drift of an immense carbon monoxide plume from a source in Southeast Asia across the Pacific to North America. The pollution reaches North America in fairly high concentrations. In the winter, a major source of pollution captured by Terra is the burning of fossil fuels for mass transportation and business and residential heating in the northern regions of the planet which is observed traversing a majority of the hemisphere.

This August 27, 2001 image from NASA's Terra satellite shows the smoke from a California fire west of Lake Tahoe rising to the north. The red dots near the center of the image represent a fire currently burning. The San Francisco bay area is also visible just below the center of the image along the coast. (Courtesy: NASA/NCAR/CSA

Carbon Monoxide in the Atmosphere
Human activities cause nearly half of the world's carbon monoxide pollution. It is produced by the deficient or incomplete combustion of gasoline and other fossil fuels such as used in automobiles, furnaces and industry, as well as by the burning of natural organic matter such as wood and grasses (from fireplaces to forest fires). Not only is carbon monoxide dangerous by itself, but it also produces ozone, a greenhouse gas that forms naturally in the upper atmosphere but is dangerous to humans.

According to NASA, Terra has allowed scientists to observe carbon monoxide in the atmosphere from two to three miles above the Earth's surface where it forms ozone through interaction with other gases. Once the pollutant moves higher in the atmosphere, high winds can blow it rapidly across great distances. By tracking this movement, scientists can also track the movement of other pollutants that are also produced by combustion but are not easily detected from space.

Using the Data

Such technology not only gives scientists details on the state of the Earth's current condition, but the information it produces will help scientists, engineers, researchers, consumers and industry plan a course of action to correct the problems. People have known for years that the burning of fossil fuels and organic matter creates pollution, but technology such as the Terra satellite provides specific detail on what happens to that pollution. Contrary to many theories and common beliefs that air pollution simply dissipates in the atmosphere or is remedied by Earth's natural processes, we have learned that these pollutants not only can remain in the atmosphere for very long periods of time, but they can reach anywhere in the world. The Antarctic is a very good example. This pristine, ice-covered continent is untouched by industry and dense human populations that are strong sources of pollution. Yet, traces of these pollutants can be found in Antarctica's ice shelves and the seawaters that surround it.

Methane hydrates, found in large deposits underneath ocean floors, could meet the world's energy needs for centuries, but mining them and their environmental impact are still questionable. Pictured here, the vapor from methane hydrate crystals is ignited simply by passing a flame over them. (Courtesy: GSJ Symposium on Methane Gas Hydrates)

Armed with this information, scientists and engineers -- supported by industry -- are racing to develop alternative energy to the point where it can effectively and affordably replace the need for fossil fuels, and to find ways to burn fossil fuels more efficiently. Already, hybrid combustion cars -- which operate primarily from an electric engine and is supported by a separate combustion engine when needed -- have entered the mass marketplace and are expected to develop firm roots among consumer over the next ten years. The hybrid automobile is seen as a bridge between today's all-combustion engines and the non-combustion engines of the future. Solar energy is slowly becoming utilized as a feasible alternative form of energy, but has not yet been able to meet the extraordinary energy demands of industry. Water and wind have been tapped as energy sources throughout history, and they will continue to serve as important sources for part of the world's energy needs.

The key challenges may not be pollution so much as the dwindling fossil fuel reserves that remain. With fossil fuels being consumed faster than they form, we can expect to deplete them before the end of this century. Methane hydrates could solve the planet's energy needs for centuries to come, but the impact they could have on the environment is poorly understood.

-- Eric McLamb

Did you know...?

Sulphur dioxide, the primary cause of acid rain, is released from burning of fossil fuels and industrial plants.

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