<![CDATA[Grist - Comment Feed for We’ll need a lot of Socolow and Pacala’s wedges]]> Grist Comment Feed en Comment #1 by Philip Sutton http://www.grist.org/article/is-450-ppm-or-less-politically-possible-part-1/ Tue, 01 Apr 2008 23:48:10 -0700 http://www.grist.org/article/is-450-ppm-or-less-politically-possible-part-1/1 450 ppm? or a safe climate level

Hi Joseph,

I can't quite follow why you would keep working on a 450 ppm target when Hansen et al. have just indicated that 450 (plus or minus)is most likely the threshold for the complete deglaciation of the earth - with another approx. 80 metres of sea rise as an eventual consequence?

Also we are 2-5 years from an ice-free Arctic ocean in northern summer times, and the heating that will flow from the Arctic ice loss is likely to push the melting of both Greenland (with major direct sea level rise consequences) and the permafrost (with major direct greenhouse gas boosting consequences).  I know of no credible climate scientist who believes we can have a safe climate with the permanent absence of the Arctic summer. To get the Arctic summer sea ice back to its necessary full extent we need at least a 0.3ºC COOLING as fast as possible - before too much more damage is done and too many more climate dominoes start to fall.

I would think our real target is a complete economic restructuring over the next decade or so - so that we can achieve zero greenhouse gas emissions (real, not notional via offsets), and to create an economy that is able to rapidly draw down the excess CO2 that is blocking a 0.3ºC cooling - currently the excess is about 200 billion tonnes of CO2.  And until the natural cooling process kicks (driven by declining greenhouse gas levels in the air) we will probably also have to invest in enhancing natural cooling processes (getting more cloud cover due to boosting ocean health or growing back forests) and we might have to supplement this with artificial albedo boosting measures.

If you want to see this argument spelled out in more detail have a look at the report Climate Code Red downloadable from:  climatecodered.net

If this set of tasks seems impossible then it just makes it clear that our real challenge is to work out how to make it possible.  Working on other (also apparently 'impossible') targets like a 450 ppm stabilisation of atmospheric CO2, that will in any case not actually prevent 'run-on' global heating - even if they were to succeed - seems to me to be a diversion of effort from the real thing.

Cheers, Philip

]]> 450 ppm? or a safe climate level

Hi Joseph,

I can't quite follow why you would keep working on a 450 ppm target when Hansen et al. have just indicated that 450 (plus or minus)is most likely the threshold for the complete deglaciation of the earth - with another approx. 80 metres of sea rise as an eventual consequence?

Also we are 2-5 years from an ice-free Arctic ocean in northern summer times, and the heating that will flow from the Arctic ice loss is likely to push the melting of both Greenland (with major direct sea level rise consequences) and the permafrost (with major direct greenhouse gas boosting consequences).  I know of no credible climate scientist who believes we can have a safe climate with the permanent absence of the Arctic summer. To get the Arctic summer sea ice back to its necessary full extent we need at least a 0.3ºC COOLING as fast as possible - before too much more damage is done and too many more climate dominoes start to fall.

I would think our real target is a complete economic restructuring over the next decade or so - so that we can achieve zero greenhouse gas emissions (real, not notional via offsets), and to create an economy that is able to rapidly draw down the excess CO2 that is blocking a 0.3ºC cooling - currently the excess is about 200 billion tonnes of CO2.  And until the natural cooling process kicks (driven by declining greenhouse gas levels in the air) we will probably also have to invest in enhancing natural cooling processes (getting more cloud cover due to boosting ocean health or growing back forests) and we might have to supplement this with artificial albedo boosting measures.

If you want to see this argument spelled out in more detail have a look at the report Climate Code Red downloadable from:  climatecodered.net

If this set of tasks seems impossible then it just makes it clear that our real challenge is to work out how to make it possible.  Working on other (also apparently 'impossible') targets like a 450 ppm stabilisation of atmospheric CO2, that will in any case not actually prevent 'run-on' global heating - even if they were to succeed - seems to me to be a diversion of effort from the real thing.

Cheers, Philip

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