President Obama and his administration take pains to stress that their climate and environmental policies will be informed by the best science available. And that is as it should be, but the entire task can be complicated by the fact that sometimes the best available science may not be good enough for the task at hand.

Anthony Watts’s report on the Surfacestations project—Is the U.S.…

“Binding emissions targets for the developing nations are out of the question.”

– Eileen Claussen, Pew Center on Global Climate Change, March 2009

As I demonstrated in my analyses last week (here and here), the impact on global temperatures of U.S. actions to reduce greenhouse gas emissions pursuant to the Waxman-Markey climate bill (which called for a whopping 83% reduction by 2050) was close to nil. Or more precisely, about 0.05°C (0.09°F) by the year 2050, expanding to maybe 0.1°C–0.2°C by the end of the century, depending on, among other things, which future emissions course is assumed as the baseline.

And as the negotiations continue into the specific details of the proposed legislation, the emission reduction schedule has begun to slip—and so too does the potential climate impact.

So what is the temperature impact of a dirty Waxman-Markey bill versus the “clean” bill’s 0.05°C/0.09°F?…

Yesterday’s MasterResource post looked at the potential climate impacts of the proposed Waxman-Markey Climate Bill. But I limited my analysis to only U.S. actions—after all, Waxman-Markey can’t mandate international man-made greenhouse gas reduction timetables. But, what would happen if the rest of the world wanted to join in?

The Bottom Line

The ability of the industrialized world, through emissions reductions alone, to impact the future course of global climate is minimal. If the U.S., Canada, Australia, Japan, Europe, and former Soviet countries all limited their emissions of greenhouse gases according to the schedule laid out under Waxman-Markey—a monumental, unexpected development—it would, at most, avoid only a bit more than one-half of a °C of projected global warming (out of 4.5°C—or only about 10%). And this is under worst-case emissions assumptions; middle-of-the-road scenarios and less sensitive climate models produce even less overall impact.…

Editor Note: Using mainstream models and assumptions, Mr. Knappenberger finds that in the year 2050 with a 83% emissions reduction (the aspirational goal of Waxman-Markey, the beginning steps of which are under vigorous debate), the temperature reduction is nine hundredths of one degree Fahrenheit, or two years of avoided warming by 2050. A more realistic climate bill would be a fraction of this amount. The author will respond to technical questions on methodology and results and invites input on alternative scenarios and analyses.

“A full implementation and adherence to the long-run emissions restrictions provisions described by the Waxman-Markey Climate Bill would result only in setting back the projected rise in global temperatures by a few years—a scientifically meaningless prospect.” (from below)

The economics and the regulatory burdens of climate change bills are forever being analyzed, but the bills’ primary function—mitigating future climate change—is generally ignored.…