November 20, 2007

The Big Secret: Climate Bills Result in No Meaningful Impact on Global Temperature

Filed under: Climate Politics

Three bills have been introduced to Congress which have as a goal to slow the rate of global temperature rise, and in doing so, avert some type of putative global climate catastrophe. They propose to do so by reducing U.S. emissions of greenhouse gases.

At the requst of Senators Bingaman and Spector, the EPA has analyzed the effectiveness these bills as measured by the net impact each will have ameliorating the rise of global atmospheric carbon dioxide (CO2) concentrations (and thus global climate change) by the end of this century. What they found was certainly not encouraging, at least for anyone who thinks that the U.S. alone can have any impact on global climate via new regulation of emissions.

The three bills whose impact the EPA assessed were:

1. Lieberman-McCain, “Climate Stewardship and Innovation Act,” (S.280),
2. Kerry-Snowe, “Global Warming Reduction Act,” (S.485),
3. Bingaman-Specter, “Low Carbon Economy Act,” (S.1766).

All three require massive cut-backs in U.S greenhouse gas emissions—an impossible task with existing technology (assuming that is, that the current resistance to nuclear power is not swiftly overcome or that we wish to remain a first world country):

• Bingaman-Specter (S. 1766) calls for reducing covered emissions to 60% below 2006 levels in 2050,
• Lieberman-McCain (S. 280) calls for reducing covered emissions to 60% below 1990 levels in 2050,
• Kerry-Snowe (S. 485) calls for reducing covered emissions to at least 65% below 1990 levels in 2050.

EPA found that while the three bills differed somewhat in the timing, degree, and scope of the greenhouse gas emissions reductions that they seek to implement, they all produce about the same impact on end-of-the-century atmospheric carbon dioxide concentrations—a direct measure of their success. And, that the impact is exceedingly small, ranging from a reduction atmospheric CO2 levels of 23 to 25 ppm from where they would otherwise be under the reference emissions scenario employed by the EPA (see Figure 1, solid curves).

Figure 1. The projected future course of atmospheric carbon dioxide concentrations under various emissions scenarios used by the EPA. The solid red curve shows the EPA’s reference case resulting in 719 ppm by 2100. The solid curves beneath it represent the projected concentration pathway produced by the three climate bills, which result in concentrations of between 693 and 695 by 2100. (source:

The EPA finds that the climate bills will lower the projected atmospheric carbon dioxide concentration from 719 ppm in 2100 down to either 696 ppm for bills S.1776 and S.280 or 694ppm for S.485. The U.S. contribution to the global CO2 concentration reduction remains the same with or without international actions (that are not in any way tied into the bills themselves).

The EPA stopped short of telling us what we all really want to know—which is how much the U.S. emissions reductions will help slow down global warming.

So, we’ll step up and run the numbers ourselves.

We’ll use as our basis the landmark study by National Center for Atmospheric Research (NCAR) scientist Dr. T.M.L. Wigley that was published in 1998 to assess the impacts of the CO2 emissions reductions mandated by the Kyoto Protocol on global average temperature. For those of you unfamiliar with Wigley’s results, he found that if the entire world (including the United States) fully met their emissions reduction obligations laid out in the Kyoto Protocol (which, by the looks of things, few if any countries will actually achieve) that the amount of future global warming that would be “saved” would amount to about 0.07ºC by the year 2050 and 0.15ºC by 2100. (We define “saved” in this context as the difference in projected temperature increase from the reference scenario to the policy scenario). How much of a CO2 reduction produced the whopping 0.15ºC temperature savings by 2100? About 40ppm. That’s right, Wigley calculated that a complete adherence to the Kyoto Protocol by every country involved including the United States would result in ~40 ppm less CO2 than otherwise was projected to be there in 2100 and that this decrease would result in a global average temperature rise that was 15 one-hundredths of a degree Celsius less than projected to otherwise occur—a reduction which was scientifically meaningless and bordering on the limits of detectability.

And the three Senate climate bills would do even less!

Recall that EPA calculates that the climate bills will reduce future atmospheric CO2 concentrations by 23 to 25 ppm. That is about 60% of the reduction calculated by Wigley for his global Kyoto scenario. Since the temperature savings scales roughly with the CO2 concentration savings (especially at these small quantities), the climate bills “save” about 60% of 0.15ºC or just less than one tenth, that’s 0.1, degrees Celsius.

One tenth of one degree Celsius for an enormous economic hit—the EPA calculated that S.280 (Lieberman-McCain) would lower the U.S. GDP annually by 1.1% to 3.2% ($457 billion to $1,332 billion) by the year 2050. EPA’s analysis of the economic effects of the other bills has not been completed yet (see here for updates).

That’s a lot of lost capital to produce virtually no climate impact. No polar bears are saved, no droughts averted, no hurricanes tamed. Nada. Except, a lot less cash in the pocketbook.

When it comes down to it, these facts will make this a hard sell to the American populace at large.


Wigley, T.M.L., 1998. The Kyoto Protocol: Co2, CH4, and climate implications. Geophysical Research Letters, 25, 2285-2288.

U.S. Environmental Protection Agency, 2007. EPA Analysis of Bingaman-Specter Request on Global CO2 Concentrations Part I,

U.S. Environmental Protection Agency, 2007. EPA Analysis of The Climate Stewardship and Innovation Act of 2007,

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