Positive feedback in global warming...
Most studies indicate that global warming is happening quicker than previously thought.Positive feedback is probably responsible for some of it.
An example will explain how this works:Arctic ice is highly reflective and sends a good fraction of sun's energy back into spcae. If the ice melts then it is replaced by darker looking water which reflects less light and absorbs more of the incident energy causing additional warming. This warming then melts more ice that then results in still greater absorption of solar energy. And so the cycle goes on, feeding on itself.
All the evidence is that the amount of arctic ice is shrinking rather rapidly.
Another example of positive feedback may be the oceans that are vast sinks of carbon di-oxide. Water vapour and carbon di-oxide are two main gases in the atmosphere that prevent energy from escaping from the earth. Warmer oceans create more water vapour and also absorb less carbon di-oxide. This then creates more warming etc.Recent studies have found that oceans are absorbing only half the amount of carbon di-oxide from the atmosphere now compared with the amount they soaked up 12 years ago.
This is too rapid a change and a real cause of worry about a run-away situation resulting... Need to do something positive...!
This post was published previously in Oct 2007