That’s the message of this op-ed from Matt Ridley in the Wall Street Journal:
Mr. Lewis tells me that the latest observational estimates of the effect of aerosols (such as sulfurous particles from coal smoke) find that they have much less cooling effect than thought when the last IPCC report was written. The rate at which the ocean is absorbing greenhouse-gas-induced warming is also now known to be fairly modest. In other words, the two excuses used to explain away the slow, mild warming we have actually experienced—culminating in a standstill in which global temperatures are no higher than they were 16 years ago—no longer work.
In short: We can now estimate, based on observations, how sensitive the temperature is to carbon dioxide. We do not need to rely heavily on unproven models. Comparing the trend in global temperature over the past 100-150 years with the change in “radiative forcing” (heating or cooling power) from carbon dioxide, aerosols and other sources, minus ocean heat uptake, can now give a good estimate of climate sensitivity.
The conclusion—taking the best observational estimates of the change in decadal-average global temperature between 1871-80 and 2002-11, and of the corresponding changes in forcing and ocean heat uptake—is this: A doubling of CO2 will lead to a warming of 1.6°-1.7°C (2.9°-3.1°F).
This is much lower than the IPCC’s current best estimate, 3°C (5.4°F).
Honestly, that’s still a bit concerning to me but it does suggest to me that the measures needed to prevent even that relatively smaller increase in average global temperatures should be subjected to cost-benefit analysis.
As I’ve said here any number of times, I think we should stop subsidizing the production of greenhouse gases here. Those subsidies are far-reaching, including policies ranging from ethanol subsidies to highway construction to bailing out automobile companies. I also think that we should be thinking in terms of engineering solutions to remove carbon dioxide from the atmosphere rather than draconian restrictions on developed countries to prevent them from releasing them.
Note, too, that China’s greenhouse gas production now exceeds ours and is increasing rapidly. The United States and other OECD countries might consider imposing a carbon duty on Chinese products as long as Chinese policies mean that China’s release of greenhouse gases will continue to grow.