Insufficient forcing uncertainty underestimates the risk of high climate sensitivity,
Geophys. Res. Lett., doi:10.1029/2009GL039642, in press.
[PDF] (accepted 17 July 2009)
Unlike Lindzen and Choi, this has been accepted and is in press. (That link to the PDF won't work for everybody.)
From the abstract of Tanaka et al.:
ABSTRACT
Uncertainty in climate sensitivity is a fundamental problem for projections of the future
climate. Equilibrium climate sensitivity is defined as the asymptotic response of
global-mean surface air temperature to a doubling of the atmospheric CO2 concentration
from the preindustrial level (≈ 280 ppm). In spite of various efforts to estimate its value,
climate sensitivity is still not well constrained. Here we show that the probability of high
climate sensitivity is higher than previously thought because uncertainty in historical
radiative forcing has not been sufficiently considered. The greater the uncertainty that is
considered for radiative forcing, the more difficult it is to rule out high climate sensitivity,
although low climate sensitivity (< 2°C) remains unlikely. We call for further research on
how best to represent forcing uncertainty.
