The Short History of the Global Warming Theory

March 17, 2010 by jason

This article takes a step back from the usual global warming discussions I post on this website. I wanted to explore something as important to the theory of global warming as anything else - the history behind it, and the debates and controversy that got us to where we are today. Before writing this article I didn't know the answer to that question, so I looked it up. I got interested in this after reading an article titled Global warming is a hoax, invented in 1988. Skimming through the content of what at first seemed like a credibly piece of blogging, I found this a few lines down:

I stopped reading there, and decided there must be more to the story than whatever this guy had to say. So I did a little of my own research and came up with this:

Global Warming Theory in 19th century

It turns out that anthropogenic global warming wasn't invented in 1988 at all (big surprise there), but was first explicitly hypothesized in 1896 by Swedish scientist Svante Arrhenius, who claimed that the combustion of fossil fuels might result in enhanced global warming and also proposed a direct relationship between carbon dioxide concentrations and temperature. As far as I can tell, things were pretty quiet after that, and it wouldn't be almost half a century before words like global warming and the greenhouse effect would once again enter public forum.

Photograph of Svante Arrenhius, 1903 (Source: Svante Arrhenius)

Global Warming Theory before World War II

In the 1930s, when the earth had been undergoing a period of warming for the past 50 or so years, scientists assumed this was just part of a natural cycle with unattributable causes (I happen to agree with them, as I don't believe the effects of anthropogenic global warming became pronounced until the 1970s, as discussed in the last section of my first global warming article). There was one man, an Englishman by the name of Guy Stewart Callendar, who disagreed with what was, at the time, the scientific consensus. Callendar argued that rising carbon dioxide concentrations could increase global temperature - this became known as the Callendar Effect. Callendar believed that this warming would actually beneficial, and would delay the return of what he called the "deadly glaciers" (see The Discovery of Global Warming: Callendar). Regardless of the cause, the general consensus was something along the lines of "the more the better!".

Global Warming Theory during the Cold War

During the 1950s, as Callendar's claims gained credibility in the public eye, his ideas about global warming began to spark debate and with it, increasing scientific interest. Coupled with a tremendous increase in the amount of money that the US and other countries were investing in weather research during the Cold War (no, they didn't care about global warming - anything to do with the atmosphere was considered a matter of national security), new scientific models could be constructed. Among the first fruits of this research was improved data on CO2 IR absorption spectra (as those discussed in my article on radiative forcing and CO2 absorption). All this info was no doubt intended to benefit military engineers above climate scientists (Wearth, 1997).

These new models found, contrary to many previous predictions, that the buildup of CO2 in the atmosphere from burning of fossil fuels was indeed a possibility. Empirical measurements managed to prove conclusively in 1960 that CO2 concentrations were in fact rising. The digital computer was now common place in many scientific institutions, and with it came the possibility to emulate complex climate processes that had previously eluded the scientific community. I do not know of any scientific model created at this time that was particularly accurate in predicting the climate today, but I do know that the predictions of the different models varied immensely. Between debating one another on the reasons for the global temperature changes, scientists more or less agreed that, regardless of what is really going on, the climate is far more complex and sensitive than we had previously thought. Based on many of the predictions, the global climate could rise a few degrees within a century. Given the limited understanding we had at the time, and the uncertainty of the predictions, it's no surprise that a century and a couple of degrees didn't seem like enough to worry about in the 1960s.

Peace, Love, and Global Cooling

The late 60s and early 70s saw the rise of environmentalism, and with it came a growing public criticism of the way humans were treating the planet. A growing number of scientists began to support what became to be known as Global Cooling, sparking global debate on the consequences this might have in store. At the time the models were not accurate enough, and information was generally lacking enough detail to conclude exactly what was causing the cooling, but the general consensus was that it was in fact occurring. The belief that an ice age was imminent was popularized by the media at the time, although this was strongly debated among the scientific community. Some scientists also speculated that global cooling due to the emission of aerosols and small particles emitted by the combustion of fossil fuels, could have a stronger cooling force on the planet than the increases in temperature caused by the emissions of greenhouse gases such as CO2 (Rasool, 1971). The media emitted somewhat more certainty than the scientific community at the time, and created what many now remember as a time when the world thought we were going into an ice age. This simply wasn't the case, but it's stories like in this famous Newsweek article from 1975, referring to the then recent declines in global temperature observed since the 1940s, that created a very different sentiment in people at the time:

Source: Newsweek, April 28, 1975

The scientific community however, more or less agreed that there simply wasn't enough information to generate a consensus on the reasons for the cooling, or that it would continue. Referring to the possibility of drastic temperature decreases pending an ice age, B.J. Mason stated in a paper in 1976 that

Source: Symons Memorial Lecture

This is important, because I hear so many people saying that climate science is garbage because scientists were saying that the world was cooling 3 years ago. This simply isn't the case. We were unsure, and we knew it.

While we didn't understand the climate, scientists in 1970s and 1980s were beginning to understand just how complex the global climate system really was. Earlier approaches in predicting long-term climate changes had focused primarily on single factors, such as changes in orbital mechanisms and CO2 emissions, but were now beginning to realize that it was far more intricate than that. Volcanic eruptions, solar flares, and cosmic ray levels (the effects of which I discussed in my article on cosmic ray levels) all began to be considered as serious factors affecting climate. This was usually with some merit, although many began to argue that volcanic eruptions and solar flares far outweighed the effects of human activity, a statement later discovered to most likely be incorrect.

Global Warming Theory and the Late 20th Century

Increased research into the effects of other chemicals into the atmosphere during the 1970s lead researchers to discover the effects of Chlocofluorocarbons (CFCs). These chemicals were stable, non-flammable and mostly non-toxic, and were widely used in spray cans and refrigerators at the time. Through the growing research into climatic effects, scientists discovered that CFCs broke down into elementary chlorine in the presence of UV light (abundantly emitted by the sun). A single molecule of elementary chlorine was found to destroy over 100,000 ozone (O3) molecules; a discovery that lead to a world reaction and eventual cessation of the use of CFCs by the late 1990s (see Ozone Science: The Facts Behind the Phaseout).

During the 1980s and 1990s, it became increasingly apparent that the world was not cooling. Research continued to intensify, and eventually lead global governments to form the Intergovernmental Panel on Climate Change (IPCC) in 1988. In 2001, the IPCC produced a (carefully worded) scientific consensus, stating the following:

Source: IPCC 2001 Synthesis Report

This is a significant milestone, and despite recent changes to the wording, it more or less represents where we are today in terms of the global scientific view. The public remains skeptical, with a growing number of people (at least in the US) believing that there is not sufficient evidence to support global warming theory. For more information on the history of global warming, I would recommend reading The Discovery of Global Warming by Spencer Weart.