Can we halt runaway climate change? Not likely

[OKIsItJustMe]

http://www.guardian.co.uk/environment/cif-green/2009/dec/15/runaway-climate-change-two-degrees

Can we halt runaway climate change? Not likely

A lot depends on what world leaders decide in Copenhagen in the next few days, but it will be hard to avoid a 2C rise

Duncan Clark
guardian.co.uk, Tuesday 15 December 2009 14.01 GMT

Amid the dripfeed of news and gossip from Copenhagen, it's not always easy to get a handle on the bigger picture. What will the kinds of commitments currently being discussed mean for the future temperature of the planet? And, given what we've heard so far, how optimistic should we be about the chance of avoiding runaway climate change?

A lot depends on what happens in the next few days as world leaders arrive at the conference for the final negotiations. But it's already possible to draw some broad conclusions.

Currently, no deal being seriously considered by the major players in Copenhagen is ambitious enough to give the world an odds-on chance of limiting the temperature rise to 2C above pre-industrial levels – the widely accepted target for avoiding irreversible climate change.

This fact is underlined by a http://www.guardian.co.uk/environment/interactive/2009/dec/14/climate-simulator">new interactive tool on environmentguardian.co.uk that visualises recent climate scenarios from the Met Office. Of all the scenarios, the only one in which the world is more likely than not to avoid a 2C rise is the most ambitious: an emissions peak in 2016 followed by an almost unimaginably ambitious global cut of 4% or 5% per year. And even that scenario could plausibly push temperatures above 2.5C, depending on exactly how the carbon cycle and atmosphere respond to the build-up of greenhouse gases. Besides, it's also far bolder than anything Copenhagen is expected to deliver.

…

With apologies to Henry Higgins: “http://www.youtube.com/watch?v=FbFNP833qVk">Why can’t the English teach their children how to spell!?” “Visualises” indeed!
(Thank God for http://en.wikipedia.org/wiki/Noah_Webster#Speller_and_dictionary">Noah Webster!)

[Richard D]

1. A lot of words . .

. . . are spelled differently in British English. Visualises is one of them.

[OKIsItJustMe]

2. Sorry… Just my ironic sense of humour

("U" inserted to comfort my anglo friends.)

If you follow the Noah Webster link I provided, you’ll find that he is largely responsible for “Americans” spelling English as we do.

[nilram]

8. Hey, I got it...

Noah Webster had you covered.

[TxRider]

3. Define "runaway" change...

[OKIsItJustMe]

4. Here’s a decent definition

http://en.wikipedia.org/wiki/Runaway_climate_change

…

Runaway climate change is a situation in which the climate system passes a tipping point, after which internal positive feedback effects cause the climate to continue changing without further external forcings. The runaway climate change continues until it is overpowered by negative feedback effects which cause the climate system to restabilise at a new state.

…

[TxRider]

5. Under that definition, no we cannot.

We have already added enough C02 for the climate to change without any further external forcings, according to IPCC. And the climate is seeking the new equilibrium as we speak.

Under that definition we are already in a runaway condition.

[OKIsItJustMe]

6. I notice you did not use the phrase “tipping point” however…

Judging by the IPCC’s publications, if we made dramatic changes to our emissions, we might be able to avoid hitting a “tipping point.”

[TxRider]

7. I didn't need to

The paragraph defined the tipping point as the point after being reached that...

"after which internal positive feedback effects cause the climate to continue changing without further external forcings."

From what I gather from IPCC, we have already added enough c02 that the climate will continue warming even if we shot off all C02 emmisions to zero today and come to a new equilibrium in the future. That seems to fit the definition given.


It's a poor definition in that runaway is seen by many as a condition in which the earth would end up like Venus, a condition many scientists say in not actually possible...

Or some use it as a definition of the IPCC case of 4.5 degree rise in temps...

So to me it's best to just stay away from terms like "runaway" which are used so freely with so many definitions flying around.

Can we avoid a 2 degree increase, or 5 degree increase is a lot more descriptive, though a lot less sensational sounding for the media that "runaway"