[SustainableTompkins] Avoiding the GHG tipping point

[John Miller]

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
 
408 C Street, NE
Washington, D.C. 20002
 
office phone: (202) 548-4591
cell phone: (508) 404-6824
fax: (202) 675-6277
 
"This world demands the qualities of youth: not a time of life but a
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