Generals must give us their exit strategy for climate change

[OKIsItJustMe]

http://www.guardian.co.uk/environment/cif-green/2009/apr/29/climate-change-research-myles-allen

Generals must give us their exit strategy for climate change

It's not unreasonable for us to ask how today's sacrifices will meet tomorrow's climate change goals, says Myles Allen

Myles Allen
guardian.co.uk, Wednesday 29 April 2009 18.02 BST

Like many of us in these cash-strapped times, I lead a double life, fitting the job of a climate physics lecturer around the implacable 3pm primary school pick-up time. I get a range of reactions at the school gates when other parents find out that I work on climate change. Some mention how much effort they put into recycling or ask whether it really is as bad as the papers make out. Others quietly change the subject when it looks as if our work on flood risk might affect house prices.

Like all scientists, most of what I do is arcane and technical and of very little interest to outsiders. For once, however, I'm involved in a couple of studies (http://www.nature.com/nature/index.html">published today in Nature), that my fellow parents might just find interesting. The headline result of both papers is that the risk of dangerous climate change is primarily determined by the total amount of carbon dioxide that we, the human race, release into the atmosphere over all time, not by emissions in any particular year.

For example, releasing a total of a trillion tonnes of carbon causes a most likely warming of around 2C, which many scientists and governments regard as a threshold above which the risks rise steeply. A most likely warming of 2C means, of course, a substantial risk of warming higher still. Keeping the risk of warming over 2C to odds of less than one in four makes the job even harder. It cuts the total "cumulative budget" that we can get away with releasing to under three-quarters of a trillion tonnes.

Given that we have released over half a trillion tonnes already since 1750, we are left with a budget in the region of half-as-much-again to the-same-again. On current trends we'll use that up in only 20-40 years. Emissions are clearly going to have to start going down soon.

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[kristopher]

1. That's a very understandable way to present the risk

Thanks for posting it.

K&R