David Archer on how long co2 lasts in the atmosphere

 University of Chicago oceanographer
David Archer, who led the study with
Caldeira and others, is credited with
doing more than anyone to show how
long CO2 from fossil fuels will last in
the atmosphere. As he puts it in his new
book The Long Thaw, “The lifetime of
fossil fuel CO2 in the atmosphere is a few
centuries, plus 25% that lasts essentially
forever. The next time you fill your tank,
reflect upon this”3.

 the oceans also release much of that
CO2 back to the air, such that man-made
emissions keep the atmosphere’s CO2
levels elevated for millennia.

 if cumulative
emissions are high, the portion remaining
in the atmosphere could be higher than
this, models suggest. Overall, Caldeira
argues, “the whole issue of our long-term
commitment to climate change has not
really ever been adequately addressed by
the IPCC.”
The lasting effects of CO2 also have
big implications for energy policies,
argues James Hansen, director of NASA’s
Goddard Institute of Space Studies.
“Because of this long CO2 lifetime, we
cannot solve the climate problem by
slowing down emissions by 20% or 50%
or even 80%. It does not matter much
whether the CO2 is emitted this year,
next year, or several years from now,” he
wrote in a letter this August. “Instead...
we must identify a portion of the fossil
fuels that will be left in the ground, or
captured upon emission and put back
into the ground.”