Azara Blog: Avoiding Dangerous Climate Change

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Date published: 2005/01/31

The BBC says:

One of the most highly charged topics preoccupying the governments of the world is to be thrashed out at a UK conference starting on Tuesday.

But Avoiding Dangerous Climate Change, a three-day meeting at the Met Office in Exeter, is mainly about the science.

The participants, more than 200 in all, will try to agree how to define what is a danger level, and what it should be.

This, they hope, will lead to a better understanding of methods the world can employ to avoid catastrophic warming.
It will try to answer three questions:

The secretary of the steering committee which has organised the conference is Dr Geoff Jenkins, a veteran of 30 years' work at the Met Office.

He told the BBC News website: "The UN climate convention calls on countries to act to prevent 'dangerous anthropogenic (human-caused) interference with the climate system' from the build-up of greenhouse gases.

"So the conference will be aiming to identify what's dangerous and what that implies for greenhouse emissions, though without specifying any actual numbers.

"It'll look at the impacts for different levels of warming, but it's very unlikely to say, for example, that a rise of 2C is the limit so we shouldn't let atmospheric carbon concentrations rise beyond 450 parts per million (ppm)."

A number of the papers to be presented deal with areas where science is far from certain about what will happen but remains apprehensive - high-impact low-probability events, as they are known.

Examples include the possible melting of the Greenland ice sheet, disruption to ocean circulation, and the fate of methane hydrates - lumps of frozen methane on the seabed which could conceivably thaw and accelerate the warming process.

The European Union has said global average temperature should not rise more than 2C above its present level in order to avoid damaging climate change.

One paper, Emission Implications Of Long-term Climate Targets, says carbon dioxide concentrations will have to be stabilised at 450 ppm or lower to achieve a 50% certainty of reaching the EU target.

They are already at almost 380 ppm, up from about 280 ppm before the Industrial Revolution, and have recently been rising at two ppm annually.

"High-impact low-probability events" make for sexy television but hopefully most of the conference will be about more mundane but relevant matters. (450-380) / 2 = 35 years to reach 450 ppm at the current annual increase, so if you believe that an increase of 2C is the end of the world (as many people seem to claim) then that still gives some time to sort things out. (Of course the increase could accelerate, making the "end of the world" sooner.)

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