Carbon Dioxide Tipping Point
Rising Greenhouse Gas Emissions an Environmental Doomsday Clock
Sep 1, 2008
Man-made greenhouse gas emissions continue to increase. Carbon dioxide (CO2) is the single most important man-made greenhouse gas in the atmosphere. Since the industrial revolution CO2 and other greenhouse gas emissions have been increasing. There may be a carbon dioxide “tipping point” after which it may be impossible to reverse the trend.
Past Levels of Carbon Dioxide
The World Meteorological Organization’s bulletin “The State of Greenhouse Gases in the Atmosphere using Global Observations through 2006” states, “For about 10,000 years before the industrial revolution, the atmospheric abundance of CO2 was nearly constant at 280 ppm”.
Present Levels of Carbon Dioxide
David Adam, writing in The Guardian (UK), (“World carbon dioxide levels highest for 650,000 years”, May 13, 2008), states, “Scientists at the Mauna Loa observatory in Hawaii say that CO2 levels in the atmosphere now stand at 387 parts per million (ppm), up almost 40% since the industrial revolution.” This increase in carbon dioxide corresponds to an increase in world temperature levels. The United Nations Environment Programme, on its “Observed Climate Trends” website says, “The mean global surface temperature has increased by about 0.3 to 0.6°C since the late 19th century and by about 0.2 to 0.3°C over the last 40 years, which is the period with most reliable data. Recent years have been among the warmest since 1860.”
Carbon Dioxide Tipping Point
Neither the Intergovernmental Panel on Climate Change (IPCC) nor any national environmental agency has set a definitive figure as a carbon tipping point. Some environmental scientists and organizations have zoned in on various concentrations of carbon dioxide as significant.
- Dr. Malte Meinshausen, in “Emission pathways and concentration levels under a 2 degrees Celcius climate target” (Potsdam Institute for Climate Impact Research, 2007) argues that levels under 400ppm CO2 give the best chance of limiting the increase in world temperature to 2 degrees Celsius, while anything higher makes catastrophic rises more likely.
- Professor Johan Rockström, Executive Director of the Stockholm Environmental Institute said (June 23, 2008), “The CO2 threshold under discussion is too high. Today, the scientific community has a pretty clear picture of how much CO2 our atmosphere can sustain, and there is growing evidence that 350 PPM should be our target, rather than 450 PPM."
- “Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations” released by the U.S. Climate Change Science Program (CCSP) in July 2007 predicts, “As a result, global CO2 emissions more than triple between 2000 and 2100, and emissions are rising at the end of the twenty-first century in all three reference scenarios.”
Environmental Doomsday Clock
If carbon dioxide and temperature levels begin to force the release of naturally trapped carbon dioxide from carbon sinks such as forests and permafrost, or limit the ability of nature to absorb carbon dioxide in the oceans, the planet will face its environmental doomsday clock. There are signs that this may be already occurring.
- In The Times (UK), (May 18, 2007), Lewis Smith reports, “Researchers have found that the Southern Ocean is absorbing an ever-decreasing proportion of carbon dioxide in the atmosphere. The excess carbon, which cannot be absorbed by the oceans, will remain in the atmosphere and accelerate global warming, they said.”
- The World Wildlife Fund (WWF) report titled “The Amazon's Vicious Cycles: Drought and Fire in the Greenhouse” says, "Global warming may lead to the displacement of large areas of eastern and central Amazon forest, reinforcing a drying trend.”
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