Wed, 04 Apr 2007 17:29:23 -0500
Such an assessment must consider threats on all space scales from local to global.
However, with respect to risk due to the addition of CO2, in terms of both a threat to the climate
system, and to the environmental system in general, Jim Hansen (and others) claim about how we are
approaching a “tipping point” is an opinion; it is not based on scientific peer reviewed studies and
certainly is not a well accepted view among most climate scientists.
Their gross overstatement, presumably are made to force policy action, and the media have picked up
on their extreme positions (it certainly sells news).
I agree that the added CO2 is a climate forcing that we should limit, but it is not the only important
climate forcing, and may not even be as important as aerosol and land use/land cover change forcings
in affecting climate as we show in our new paper:
on the radiative forcing due to CO2.
On your suggestion to poll climate scientists, this is, of course, a worthy idea.
However, new insight is never achieved by majority vote, but rather by mavericks proposing new
science, which is accepted if it can not be scientifically refuted.