[SustainableTompkins] Avoiding the GHG tipping point

[bosak at ibiblio.org]

Thanks very much for following up on my question.  A 70-90 percent
reduction is about what I would guess, too, but I hope that we can
find a calculated estimate somewhere.  If anyone runs across
something, please let me know.

Jon

> Jon,
> See Jared Duval's comments below (he spoke at last week's Engineers for
> a Sustainable World annual conf in Iowa City-I will be sending out my
> notes from the conf- where he referenced Jim Hansen from NASA)
> Complicated, controversial topic, hope this helps.
> John
>
> Hi John,
>
> Thanks for the email. Hansen has said that emissions need to peak and
> decline no later than 2015 if we are to have a shot at avoiding the
> "climate tipping point" where sea levels could rise 80 feet, 60%
> extinction of species etc. He wrote about this in the NY Review of Books
> here, http://www.nybooks.com/articles/19131
>
> Most scientists say that to stabilize the climate we need to reduce our
> emissions between 70 -90% by 2050.
>
> As far as the specific CO2 concentration in the atmosphere, the
> International Climate Change Taskforce said we should set policy so as
> not to go above 400 ppm (their report is here,
> http://www.tai.org.au/Publications_Files/Papers&Sub_Files/Meeting%20the%
> 20Climate%20Challenge%20FV.pdf#search=%22international%20climate%20chang
> e%20taskforce%22
>
>
> Michael Oppenheimer, the famed climate scientist from Princeton said we
> must not go above 450 ppm. So that 440 figure is certainly within the
> accepted range. His question about how much we would need to reduce
> emissions by to get there is a good and important one that I do not know
> the answer to. However, my hunch is that the 400 -450 ppm numbers and
> the 70-90% reductions by 2050 numbers are correlated somehow. I'll let
> you know if I find out more.
>
> Thanks,
> Jared
>
> Jared Duval
> National Director, Sierra Student Coalition
>
> www.ssc.org
>
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> Washington, D.C. 20002
>
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> state of mind, a temper of the will, a quality of  imagination, a
> predominance of courage over timidity, of the appetite for adventure
> over the love of ease." -RFK
>
>
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