Climatologists predict catastrophic consequences when average global temperatures increase by 2 degrees Centrigrade. The global average is currently 0.74 degrees Centrigrade above pre-industrial temperatures, and Australia's average is higher still. Over the past 2 million years, temperatures have never been more than 2 degrees Centrigrade warmer than at present.
Feedback processes in climate are a natural occurrence. Positive or negative feedback is a major contributor to the shifts from glacial to interglacial periods and back again. These processes accelerate the warming or cooling of the earth. They are reactions in the biosphere triggered by climate change.
Examples of feedback are the large changes in the earth's albedo: reflection of the sun's heat from white surfaces; or absorption of heat by dark surfaces. When the planet warms, polar ice-melt increases exposing a greater expanse of dark surface from the sea. Thiss then, promotes more warming, and still more ice melt. Or, when the planet warms, life in the oceans changes in such a way that the oceans' ability to absorb carbon is diminished. More carbon dioxide remains in the atmosphere, thus promoting more warming. As temperatures rise and precipitation changes, organisms could respond by releasing carbon from soils and biomass, creating another feedback loop. These are examples of positive feedback but negative feedback also comes into play and eventually halts global hemming thus preventing a `runaway' situation.
Feedback is critical in determining impacts now and in the not too distant future because the world's vegetation, including its forests, contains some 600 billion tonnes of carbon; tundra, permafrost and other, soils contain about 1,600 billion tonnes of carbon, and 10,000, billion tonnes of methane; and the oceans nearly 40,000 billion tonnes of carbon.
In comparison, the atmosphere currently contains about 750 billion tonnes (figure from early 2000s) (At the time of writing this document, the CSIRO reported that recent estimates have doubled the amount of CO2 and methane stored in the permafrost, which is already melting.) It is not difficult to see, from these figures, why further warming of the planet could lead to a very rapid escalation of our self-made climate change crisis, and much higher temperature and sea level rise than forecast by the T CC.
HAVE WE REACHED A TIPPING POINT ?
Soil, vegetation. and the world's oceans between them absorb some 50% % of CO2 emissions, so changes to the biosphere as temperatures rise is of critical importance and yet is largely ignored.
If we continue emitting greenhouse gases at present rates - and nothing we are doing yet suggests otherwise - then much of our soils, forests and oceans will be transformed into CO2 sources rather than sinks. This, of course, would add very significantly to projected temperature rise. It is thought that a tipping point grill be reached when positive feedback is speeded up to such an extent that the earth's balancing mechanisms will be overwhelmed and we will have unleashed a runaway global climate change. At such a point, it is considered that no matter what action is taken to reduce human impacts, it would have no effect.
Increasing numbers of scientists, and science writers, believe feedback is already accelerating warming of the planet and that a tipping point may have been reached. For example, Barrie Pittock of the CSIRO says that the frequency and severity of droughts in southern Australia greatly exceeds climate change forecasts for so early in the 21 ' century.
Responding to the Garnaut Climate Change Review, 2008, three organisations working on climate change issues: Friends of the Earth (FOE) Vic., Greenleap Strategic Institute and Carbon Equity said that Arctic floating ice is headed towards rapid summer disintegration as early as 2010, a century ahead of IPCC projections, saying that a rise in sea levels by as much as 5 metres by the turn of the century is not unreasonable. Record ice melt occurred in 2005 and 2007, and improved slightly in 2008 with a cooler year.
James Hansen, director of NASA's Goddard Institute for Space Studies believes that the reason for the massive and rapid ice melt is that climate is hitting a tipping point a century ahead of projections. Hansen recently said he now considers 350 ppm of carbon in the atmosphere is the critical concentration to trigger a tipping point. We have already exceeded this level (see above).
In 2007, researchers at Bristol University, in the UK, reported that a previously unexplained surge in carbon dioxide levels in the atmosphere in recent years is due to more greenhouse gasses escaping from trees, plants and soils, and making vegetation less able to absorb carbon pollution pumped out by human activity. The severe drought in the Amazon Basin in 2005 is the type of extreme event that will greatly speed up carbon emissions from forests.
James Lovelock, best known as the creator of the Gaia hypothesis, expects that within 100 years 80% of the human race will be wiped out. He became convinced of the irreversibility of climate change in 2004.
Ally Fricker 2008-2010
This is produced by the group PRECIPICE
(People Representing Ecological Consciousness and Integrity of the Planet Instead of Committing Ecocide)
Phone (O8) 8581 8255.
International Phone (61) 8 8581 8255.
Write:
Ally Fricker
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ROBERTSTOWN SA
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AUSTRALIA
Ally Fricker
RSD 3
ROBERTSTOWN SA
5381
AUSTRALIA
or Email kbarrett@adam.com.au.
