Tipping point (climatology)
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The tipping point in the study of the Earth's changing climate is the point at which change due to human activity brings about sufficient new processes in nature to make any human reversal of the change impossible.
Man made or anthropogenic global warming (AGW) proceeds by changing the composition of gases in the Earth's atmosphere by the emission of greenhouse gases such as carbon dioxide and methane. Remedial action to restrain the rate of change is proposed by reducing greenhouse gas emissions to slow down and stop and eventually reduce their build up.[1]
As warming proceeds it brings about changes to the natural environment which may result in other changes. For example, warming may begin to melt the Greenland ice sheet. At some level of temperature rise, the melt of the entire ice sheet will become inevitable, even though complete melting may not occur for millennia. Thus a "tipping point" may be passed without any immediately obvious consequences. Nor does the use of tipping point imply any acceleration of the warming process.
Some eminent scientists, notably James Hansen, NASA's top climate scientist believe this point has already been reached with carbon dioxide levels currently at 385 ppm.[2]
Other scientists maintain the term is too vague for a non-linear system such as the Earth's climate where they may be a number of states where conditions may flip and go rapidly into another state and other conditions which may return it to equilibrium. It has been suggested the phrase is more a political slogan to rally support for action to mitigate greenhouse gas emissions. [3]
[edit] Notes
- ^ Earth's Climate Approaches Dangerous Tipping Point Environment News Service (ENS), June 1, 2007. Accessed April 2008
- ^ Earth in crisis, warns NASA's top climate scientistPhysOrg.com , April 07, 2008 . Accessed April 2008.
- ^ Runaway tipping points of no return Gavin Schmidt, Real Climate Blog, 5 July 2006. Accessed April 2008
[edit] References
- International Taskforce: Global Warming Close to Tipping Point By J.R. Pegg, Environment News Service (ENS), January 25, 2005. Accessed April 2008.
- Debate on Climate Shifts to Issue of Irreparable Change Some Experts on Global Warming Foresee 'Tipping Point' When It Is Too Late to Act. By Juliet Eilperin, Washington Post , January 29, 2006. Accessed April 2008.
- Global warming: passing the 'tipping point' By Michael McCarthy, Environment Editor, The Independent, 11 February 2006. Accessed April 2008.
- NASA: Danger Point Closer Than Thought From Warming 'Disastrous Effects' of Global Warming Tipping Points Near, According to New Study. By Bill Blakemore, ABC News, May 29, 2007. Accessed April 2008.
- Global Warming: Passing The 'Tipping Point' By Michael McCarthy , 11 February 2006, The Independent. At Counter Currents. Accessed April 2007
