According to the IPCC’s 4th Report, the melting of the Greenland ice-sheet (a major contributor to sea level rise) could not be included in sea-level predictions because we had no model for such a complex “non-linear” process. Their solution was to discount, for now the potential contribution of a three km thick mountain of ice poised to melt and slide into the sea.
The great insight offered by James Lovelock in “Gaia”, is that our own physiology provides the model . Planet earth, being a web of complex self-regulating systems, operates very much like a human body. Terminal illness gives us the template for most forms of ecological collapse. One set of changes initiates another set, and so on in a cascade of positive feedback until the whole system falls apart or enters a new steady state, ….such as death
The process of labour and childbirth follows a classic exponential curve: a long period in which apparently nothing is happening (but it really is) followed by a period in which the changes become perceptible and then a great calamitous rush in which the baby makes its appearance.
As we watch our own parents age, the same pattern is obvious – a long period in which nothing much seems to happen, followed by a few years in which the deterioration becomes pronounced, and finally the rapid decline in which our loved one quickly expires – a process which will always seem cruelly sudden but, like the eventful second stage of labour, is really entirely predictable.
Climate change is often described as a linear decline followed by some kind of far-distant ‘tipping point’, but in truth there’s no tipping point – a curve is always tipping, and each new finding redraws the curve.
The pattern of exponential change, applies to most aspects of climate change – species extinctions, ocean acidity, loss of rain forest. These can probably be equated to the multiple indices by which we plot human health (white blood cell count, blood pressure, temperature and so on). In the case of the planet, these are all downwards-trending curves, and have been for the past 30 years.
Extracted from: Prognosis for a Planet by John Collee, Sydney Morning Herald April 10th 2009, http://www.smh.com.au/environment/climate-change/poor-prognosis-for-our-planet-20090411-a3jx.html