Klimaatverandering 122

'What Is Progress?

The numbers show that this should be the real question at the Bali talks.
By George Monbiot. Published in the Guardian 4th December 2007

When you warn people about the dangers of climate change, they call you a saint. When you explain what needs to be done to stop it, they call you a communist. Let me show you why.
There is now a broad scientific consensus that we need to prevent temperatures from rising by more than 2°C above their pre-industrial level. Beyond that point, the Greenland ice sheet could go into irreversible meltdown, some ecosystems collapse, billions suffer from water stress, droughts could start to threaten global food supplies(1,2).
The government proposes to cut the UK’s carbon emissions by 60% by 2050. This target is based on a report published in 2000(3). That report was based on an assessment published in 1995, which drew on scientific papers published a few years earlier. The UK’s policy, in other words, is based on papers some 15 years old. Our target, which is one of the toughest on earth, bears no relation to current science.
Over the past fortnight, both Gordon Brown and his adviser Sir Nicholas Stern have proposed raising the cut to 80%(4,5). Where did this figure come from? The last G8 summit adopted the aim of a global cut of 50% by 2050, which means that 80% would be roughly the UK’s fair share. But the G8’s target isn’t based on current science either.
In the new summary published by the Intergovernmental Panel on Climate Change (IPCC), you will find a table which links different cuts to likely temperatures(6). To prevent global warming from eventually exceeding 2°, it suggests, by 2050 the world needs to cut its emissions to roughly 15% of the volume in 2000.
I looked up the global figures for carbon dioxide production in 2000(7) and divided it by the current population(8). This gives a baseline figure of 3.58 tonnes of CO2 per person. An 85% cut means that (if the population remains constant) the global output per head should be reduced to 0.537t by 2050. The UK currently produces 9.6 tonnes per head and the US 23.6t(9,10). Reducing these figures to 0.537t means a 94.4% cut in the UK and a 97.7% cut in the US. But the world population will rise in the same period. If we assume a population of 9bn in 2050(11), the cuts rise to 95.9% in the UK and 98.3% in the US.
The IPCC figures might also be out of date. In a footnote beneath the table, the panel admits that “emission reductions … might be underestimated due to missing carbon cycle feedbacks”. What this means is that the impact of the biosphere’s response to global warming has not been fully considered. As seawater warms, for example, it releases carbon dioxide. As soil bacteria heat up, they respire more, generating more CO2. As temperatures rise, tropical forests die back, releasing the carbon they contain. These are examples of positive feedbacks. A recent paper (all the references are on my website) estimates that feedbacks account for about 18% of global warming(12). They are likely to intensify.'

Lees verder: http://www.monbiot.com/archives/2007/12/04/what-is-progress/