Feedback Dynamics and the
Over the last two years, there has been a profound shift in the scientific understanding of the behaviour of the earth's climate system treated as a whole. Initially the climate was seen to be in a state of stable equilibrium. Man-made increase in concentration of greenhouse gases would lead to a modest rise in global temperature, a process that could be contained at any point by reducing emissions, stabilising concentration and stopping further temperature increase. Everything was under control. The timing and strategy of intervention should be economically determined and depended on "cost-benefit" analysis.
Today the climate system is recognised as being in a state of unstable equilibrium. The surface heating, caused by man-made increase in concentration of greenhouse gasses, is seen as acting as a trigger to an accelerating process of global warming driven by amplifying ("positive") feedbacks. Most of these are activated by change in temperature and are only just beginning to kick-in. There is only a limited window of opportunity in which it is possible to stop the process of runaway climate change before it passes beyond our control and precipitates "catastrophic climate change", i.e. a major extinction event.