In their article, Jorge Sarmiento and Nicolas Gruber emphasize a premise that carbon dioxide is the most prominent greenhouse gas causing global warming. In contrast, NASA, in a newspaper article two months earlier (New York Times, 31 May 2002, p. A16), stated that water vapor is the “dominant natural heat-trapping gas.” Telemetry that NASA installed recently on the satellite Aqua is intended for making a worldwide study of water vapor. 1 We already know from previous satellite measurements summarized by B. J. Mason 2 that, on average, more than 50% of Earth’s surface is covered by clouds.
Both CO2 and water vapor are considered from a historical perspective by Spencer R. Weart in Physics Today, January 1997, page 34. Experimental spectroscopic studies of infrared absorption in laboratory air cells are cited; the most recent of those studies go back to 1911. John Tyndall made spectroscopic studies in 1861 on air mixtures and concluded that water vapor was a factor of 10 stronger than CO2 in its IR absorption.
Our purpose here is to encourage revisiting and modernizing those early experiments using modern spectrographic methods to investigate a range of gas mixtures, radiation wavelengths, pressures, and temperatures. This activity would provide IR absorption coefficients having a higher confidence level. Such scientific data will help investigators and funding agencies evaluate where money is best spent to understand global warming.
