CAN INCREASING CARBON-DIOXIDE CAUSE CLIMATE-CHANGE

The realistic physical functioning of the greenhouse effect is reviewe d, and the role of dynamic transport and water vapor is identified, Mo del errors and uncertainties are quantitatively compared with the forc ing due to doubling CO2, and they are shown to be too large for reliab le model evaluations of climate sensitivities, The possibility of dire ctly measuring climate sensitivity is reviewed. A direct approach usin g satellite data to relate changes in globally averaged radiative flux changes at the top of the atmosphere to naturally occurring changes i n global mean temperature is described, Indirect approaches to evaluat ing climate sensitivity involving the response to volcanic eruptions a nd Eocene climate change are also described. Finally, it is explained how, in principle, a climate that is insensitive to gross radiative fo rcing as produced by doubling CO2 might still be able to undergo major changes of the sort associated with ice ages and equable climates.