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 There is no question as to whether or not there is a naturally occurring greenhouse effect. It helps to regulate the temperature of our planet. Without it, earth would be a much colder place. The questions are:
  1. How much are our human activities changing the natural greenhouse effect?
  2. What will the long and short-term effects be?

Scientists have been able to link previous global temperature fluctuations to the natural changing amount of carbon dioxide (carbon cycle) in the atmosphere by testing gas bubbles in ice core samples. This evidence supports the point that some natural fluctuation exists in the carbon dioxide quantities and in global temperatures, as shown by the graphs below. However scientific evidence is now indicating that human activities such as burning coal, oil, gas, and the clearing and burning of forests have released too much carbon and other heat trapping gasses thereby disrupting the natural cycle. Oddly, considering the evidence, there are skeptics.  "But certainly the evidence we have today shows we do have global warming, and that most of this is due to human action," as Ken Davidson, the director of the World Meteorological Organization (WMO) climate program told The New York Times.






The level of carbon dioxide in the atmosphere has been between 170 and 280 parts per million from the last ice age to the start of the Industrial Revolution in the early 1700s, as carbon moved in and out of natural stores. Today, we are releasing much more carbon dioxide than the natural cycle has in the past. Current levels stand at 370 parts per million,  an increase of over 23%. This is a level higher than at any time during the past 420,000 years. Some studies indicate that this may be higher than any time in the past 20 million years (Woods Hole Oceanographic Institution). The recent changes have been faster than any other time that scientists have been able to estimate through the testing of ice core samples (see "Analysis of Air Bubbles Trapped within Ice Cores" below from Nasa's Jet Propulsion Laboratory), ocean corals, tree rings, fossils, and other sources of paleoclimatic data. Human activities now put an estimated six billion tons of carbon dioxide into the atmosphere yearly. Healthy oceans are very important in this carbon cycle because plankton and the rest of the ocean biomass recycle about 50% of the six billion tons of carbon dioxide produced each year. (See our Air Pollution Page).

The increase in the concentrations of pollutants or greenhouse gases (carbon dioxide, methane, nitrous oxide and chlorofluorocarbons [CFCs]) in the atmosphere are now causing changes in weather patterns and climate.  Carbon dioxide (CO2) released by fossil fuel combustion is a leading greenhouse gas.  Two studies on climate change carried out by the National Oceanographic Data Center and the Scripps Institution of Oceanography found a direct link between rising ocean temperatures and emissions of greenhouse gases. (See Greenhouse Effect image and text below). Sydney Levitus, the lead author of the National Oceanographic Data Center study, said he believes its results are the strongest evidence to date that the Earth's climate system is being altered by human activity. 

Continue to read more about the Green House Effect.

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