Picture This: A Living, Breathing Earth
Mapping project uses satellite data to help scientists track effects of global warming
HAVE you ever seen the Earth breathing? That's what the map shown here is all about.
It charts the exchange of the heat-trapping gas carbon dioxide (CO2) between the atmosphere and the planet's land plants and soils. This is a key process in determining to what extent the release of CO2 through burning fossil fuels and land-use changes may bring on global climate warming.
The map represents the first time that satellite data have been combined with computer simulation of soil processes to show the geography of the CO2 exchanges, according to ecologist Christopher Potter of the National Aeronautics and Space Administration (NASA) Ames Research Center in Mountain View, Calif.
Growing plants take CO2 out of the air to use in photosynthesis. Soil microbes, on the other hand, release CO2 as they break down organic matter.
Green areas on the map show where Earth is ``breathing in'' as photosynthesis absorbs more CO2 than the soil releases. Red areas show where Earth is ``breathing out'' as the soil releases more CO2 than the process of photosynthesis absorbs.
This map, which Dr. Potter and his colleague Steven Klooster have constructed, represents a typical June. The two scientists are working to map other months and to extend this kind of analysis for a series of years. Potter says they now are processing data taken over the past 10 years.
Dr. Klooster explains that ``remote-sensing satellites give us a new, unique view of the Earth as a living, breathing system.'' This continuous satellite monitoring shows seasonal changes that ``help us understand the carbon distribution between the tropics and high latitudes and how that distribution changes month to month,'' he says.
The natural carbon-dioxide recycling system involves complex interactions of air, land, and sea. Volcanoes, soil-decay processes, and the sea release CO2. On the other hand, some of the gas dissolves in sea water and is stored deep within the ocean for long periods of time.