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Campaign around James Hansen's 350ppm CO2 target - (2 posts)

  1. chrisc

    New campaign site:

    Audio about it:

    The Reality Report interviews Jamie Henn of, a creative new initiative formed following the scientific understanding that atmospheric greenhouse gas concentrations need to be reduced to at most 350 parts per million.


    The documents, from James Hansen's site,

    April 2008: Target CO2: Where should humanity aim? , and Target CO2: Supporting material . Draft of submitted paper. (Note: Final draft, supercedes versions circulated in March.)

    Posted 9 years ago #
  2. chrisc

    The final version of this paper from James Hansen and associates is now out:

    The final version of "Target Atmospheric CO2: Where Should Humanity Aim?" in The Open Atmospheric Science Journal is available at

    You can click on the main paper and supporting material individually. The two are combined in one pdf on the GISS web site at

    BTW, I think that the Supporting Material contains some interesting stuff.

    NASA decided not to make a press release for the paper, but Yale did one The draft press release that I wrote and "Q&A" about the paper are at

    I'll try to read the actual paper later tonight... The abstract:

    Abstract: Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, the planet being nearly ice-free until CO2 fell to 450 ± 100 ppm; barring prompt policy changes, that critical level will be passed, in the opposite direction, within decades. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.[/quote]

    Posted 9 years ago #


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