Greenhouse Gases & Global Warming

Aurora AustralisScientists are struggling to determine exactly how, and to what extent, rising carbon dioxide levels will change the earth's climate.

In general, civilization releases about 6 billion tons of carbon (in the form of carbon dioxide) into the atmosphere every year. But only 3 billion tons stay there; the rest is absorbed into what are called carbon "sinks." Half of that dissolves into the ocean; the remainder ostensibly is taken up by vegetation.

Consequently, the performance of these sinks is an important variable in how much carbon dioxide is left in the air to trap heat and possibly raise global temperatures. Oceans absorb about one-third of all man-made carbon dioxide. They do so mainly in the cold regions because carbon dioxide dissolves easily into cold water, just like a soda in the refrigerator will stay bubbly much longer than a soda sitting in the sun. If the oceans didn't soak up carbon dioxide, the amount in the atmosphere would increase significantly faster.

Aurora AustralisAntarctica and the surrounding Southern Ocean provide scientists with a unique environment in which to study both past and present amounts of greenhouse gases in the atmosphere. The Southern Ocean is a delicate ecosystem where ocean current and microscopic sea organisms influence the release and burial of vast quantities of carbon dioxide. Analysis of biological activity and water motions suggest that rising temperatures in Antarctic waters favor the growth of microbial plants, which would help remove carbon dioxide from the atmosphere. On the other hand, a warming will liberate more carbon dioxide from tropical ocean waters, amplifying the greenhouse effect.

In examining past climate changes, scientists are collecting valuable ice core data and finding clues about natural climate patterns. Using evidence from hundreds of ice specimens, or "cores," taken far below the surface of Antarctica, investigators can analyze traces of air trapped within the ice cores for carbon dioxide content. From these samples, scientists can construct realistic models of climate change which may lead to effective solutions for the future.

Carbon Dioxide in the Atmosphere
  • All animals produce carbon dioxide when they exhale while plants take in carbon dioxide during photosynthesis.
  • Carbon Dioxide absorbs heat from the surface of the Earth, and prevents it from reflecting back into space, similar to the way a greenhouse works.
  • That is why carbon dioxide is called a "greenhouse gas."
  • Carbon dioxide and water vapor in the Earth's atmosphere together make the planet warm enough for life.
  • Of course, too much of the greenhouse gases can cause too much heating of the atmosphere: "global warming."
  • Burning fossil fuels produces a mixture of gases -and the principal one is carbon dioxide.
  • Agriculture, especially cattle raising and rice growing, produces another greenhouse gas called methane.
Did You Know?
  • models of greenhouse warmingIn order to measure changes in the global levels of greenhouse gases, you need a site as far away from industry and with as few animals and plants as possible.
  • The South Pole was chosen in 1956 as a study site for measurement of global carbon dioxide.
  • This still-running series of measurements is one of the most important carbon dioxide monitoring projects in the world.
  • Concentrations of other gases which may also be involved in global warming are also rising, and these have been added to the analyses at the South Pole.
 
Reducing Global Warming
  • The unrestricted use of cars, the burning of fossil fuels, and the waste gases produced by factories have all been shown to contribute significantly to global warming.
  • Ice Core data from the South Pole provide a baseline for global changes in greenhouse gases and are extremely valuable in making decisions about the next steps to reduce global warming.
  • The sampling in Antarctica has now been extended to a large number of other sites all over the world, providing independent checks on the rate of change.