#vaughanpratt

The White House under G.H.W. Bush acknowledged this uncertainty in a section in the Annual Report of the Council of Economic Advisers for 1990 titled “The Economy and the Environment—Report by the President” and reprinted as Chapter 11 of the above book (the lead chapter of the third section, pages 163-188). Quoting from it, “The President’s 1991 budget proposal includes $1.03 billion in funding for global climate change research. This figure reflects an increase of 57% over the current funding levels and a 100% increase over 1989 expenditures. The United States has also taken a leadership role in the Intergovernmental Panel on Climate Change, the primary international forum for consideration of the scientific, socioeconomic, and policy issues concerning global climate change.”

(For context the U.S. Global Change Research Program (USGCRP) was established by Presidential Initiative in 1989 and mandated by Congress in the Global Change Research Act (GCRA) of 1990 to “assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.” See here for its ten-year plan for 2012-2021.)

And a few paragraphs further on in that report, “Even though scientists may yet learn that no significant warming is likely, it is nonetheless worthwhile to address two distinct policy questions. First, what actions could be taken now to limit emissions of greenhouse gases and what are the likely costs of those actions? Second, what are the possible economic and other effects of warming that, if these scientists are correct, will occur in any event?”

For both these mechanisms, theory and observation were in excellent agreement long before steam punk was invented. The basic principles were developed largely in the 19th century, e.g. Clapeyron’s 1834 paper 1, while steam tables have been intensively studied since their formulation in 1934, exactly a century later 2.

/2. We know that water vapor traps heat. This was measured in the laboratory by Tyndall, and can be observed in the atmosphere from space by comparing the amount of radiation leaving Earth at wavelengths known to be blocked by water vapor with that at other wavelengths. The former wavelengths seriously notch the spectrum at the former wavelengths. (Similar observations at ozone- and CO2-trapping wavelengths show the same thing for those greenhouse gases.)

Putting 1 and 2 together, we infer that higher temperatures result in the atmosphere trapping more heat.

By how much is an excellent question that is currently above my pay grade (but it’s on my list to learn about). In the meantime, settle for the points that (a) without those greenhouse gases the Earth’s surface would be 33 °C colder and (b) the effect of increasing GHGs is to widen the portions of the spectrum that they block, leaving less of a window for heat to escape through, so wider blocked regions can be expected to have a nontrivial effect.