Tompkins Weekly 9-1-14

By Richard W. Franke

“Is the Earth’s climate changing? The answer is unequivocally ‘Yes.’” So wrote the Intergovernmental Panel on Climate Change (IPCC) in its 2001 Third Assessment Report. The IPCC’s 2001 report reflected an overwhelming scientific consensus that global warming was occurring and that human activities – in particular the release of greenhouse gases such as carbon dioxide (CO2), methane and nitrous oxide into the atmosphere – was a major cause. The Fourth and Fifth Assessment Reports have confirmed and elaborated the 2001 document.

The IPCC’s 2001 confirmation of human-induced global warming resulted from 142 years of scientific research. In 1859 the Irish physicist John Tyndall had discovered the “greenhouse effect” in which CO2 reflects certain wavelengths of solar heating back to earth. In 1895 the Swedish chemist Svante Arrhenius noted that the smoke from industrial factories was likely to eventually warm the planet.

For the first half of the 20th century most geologists and others focused on trying to explain the onset and decline of ice ages. But in 1960 the American chemist Charles Keeling announced measurements showing that C02 in the atmosphere was increasing at a rate much faster than had been thought earlier. This returned interest to what Arrhenius had said at the beginning of the century about smoke from industrial stacks eventually warming earth. Over the next 41 years increasingly intense and elaborate scientific undertakings unfolded to test the possibility that human activities were changing the atmosphere and thus the planet’s climate.

Scientists made use of the amazing technologies coming out of labs and workshops around the world. Weather balloons, rockets and satellites made it possible to accumulate vast new tables of measurements across increasingly large stretches of the atmosphere. Computers – primitive and clunky at first – grew faster and smaller and made possible calculations that would not have been feasible without their digital circuits. Mathematicians discovered “chaos theory” which indirectly helped establish the possibility that small changes in some element of earth’s climate could bring about large effects – sometimes called the “butterfly effect,” referring to the idea that a butterfly flapping its wings in one area could cause movements that turn into a tornado several hundred miles away. Nuclear testing – in what might be its only positive contribution to the world – left behind numerous isotopes that provided scientists tracer atoms to follow how the oceans absorb heat. Through it all Keeling’s measurements of the steady march of CO2 levels provided an anchor that kept bringing the debates back towards greenhouse gases.

One of the most important new sources of data came from ice cores drilled in Greenland, Antarctica and in some glaciers. The drill at Vostok in Antarctica went down 3,623 meters (11,886 feet) revealing over 400,000 years of climate history. Vostok and other ice cores helped establish the close connection between CO2 levels and world average temperatures. Scientists learned that forest cover might play a significant role in regulating greenhouse emissions – a discovery of great importance today. They also learned about the massive movements of water in the giant ocean circulations and came by accident on the danger of the ozone hole and its connection to chlorofluorocarbons (CFCs) used as propellants in some spray can products.

Another key was the development of climate modeling. After a slow start resulting from slow computers and limited data, modelers by the 1980s with better data were able to almost capture the climate in a set of mathematical equations. This allowed for the eventual predictions starting in the 1990s of the likely temperature effects of particular parts per million of CO2.

From 1960 to the ground breaking 2001 IPCC report hundreds of scientists wrote thousands of papers, attended hundreds of conferences, traipsed across deserts and ice caps, puzzled over equations that at first wouldn’t solve and engaged in all sorts of other knowledge enhancing activities. Many changed their minds several times about big issues but in the end about 97% of those most qualified in the field of climate science have joined the consensus reported by the IPCC.

Richard W. Franke writes about the history of sustainability. He is professor emeritus of anthropology at Montclair State University, a resident of Ecovillage at Ithaca and a board member of Sustainable Tompkins.

Sources:

Kolbert, Elizabeth. 2006. Field Notes for a Catastrophe. New York: Bloomsbury Publishing.

Speart, Spencer R. 2003. The Discovery of Global Warming. Cambridge, MA: Harvard University Press.