Image: © DimaBerlin/Stock.adobe.com
Dr Marc Hudson, a climate historian from the University of Sussex, discusses the surprisingly long history of scientific consensus about carbon dioxide’s role in climate warming and early media coverage of these findings.
A version of this article was originally published by The Conversation (CC BY-ND 4.0)
We have grown so used to many things. To the pictures of wildfires and cremated animals, to the ice sheets caving into the ocean, to the promises of world leaders that they will heed the ‘last chance’ warnings of scientists.
It’s hard for anyone under the age of 40 to remember a time when carbon dioxide build-up, whether it was ‘the greenhouse effect’, ‘global warming’, ‘climate change’ or now ‘climate crisis’, wasn’t in the news.
The long, hot summer of 1988 – 35 years ago – is held as the moment that world leaders began to mouth the right pieties.
Presidential candidate (and soon to be president) George H W Bush said he would use the ‘White House effect’ to fix the Greenhouse Effect (he didn’t). UK prime minister Margaret Thatcher warned of a giant experiment being conducted “with the system of this planet itself”.
But it was actually 35 years before that, that the danger of carbon dioxide build-up in the atmosphere first travelled around the world.
The role of carbon dioxide is identified
That carbon dioxide trapped heat was uncontroversial. Irish scientist John Tyndall (possibly drawing on the work of an American, Eunice Foote) had shown that it did back in the mid-1800s.
In 1895, Swedish Nobel prize winner Svante Arrhenius had suggested that – over hundreds of years – the build-up of carbon dioxide released when humans burn oil, coal and gas might trap so much heat as to melt the tundra and make freezing winters a thing of the past.
His work was challenged, but the idea occasionally popped up in popular journals. In 1938, English steam engineer Guy Callendar suggested to the Royal Meteorological Society in London that warming was underway.
‘The 1970s are a fascinating period of intense measurement, modelling, observation and thinking which produced a working consensus that there was serious trouble ahead’
But it was in early May 1953, at a meeting of the American Geophysical Union, that Canadian physicist Gilbert Plass – who had been corresponding with Callendar – told the gathered scientists that trouble was afoot.
Plass said that “The large increase in industrial activity during the present century is discharging so much carbon dioxide into the atmosphere that the average temperature is rising at the rate of 1.5 degrees [Celsius] per century”.
Media coverage
This got picked up by the Associated Press and other wire services and appeared in newspapers all around the world (even as far afield as the Sydney Morning Herald). Plass’s warning also popped up in Newsweek on May 18 and in Time on May 25.
The fact that the world was warming was already uncontroversial among scientists. But the emphatic connection with carbon dioxide made by Plass, as opposed to competing theories such as orbital wobbles or sunspot activity, was newsworthy.
Plass had become interested in the question of carbon dioxide build-up while working for the Ford Motor Company. He looked at how carbon dioxide actually functions in the real world, not just at sea level (without getting too technical. Many scientists had dismissed Arrhenius’s earlier work on the basis of false confidence that carbon dioxide worked the same there as in the stratosphere).
Plass kept working on the issue, with technical and popular publications throughout the 1950s. In 1956, he published an academic article on The Carbon Dioxide Theory of Climate Change in the Swedish scientific journal Tellus, and also a popular article in American Scientist. And he was present at the first major meetings to discuss carbon dioxide build-up.
Meanwhile, the carbon dioxide theory started getting more coverage among science journalists. George Wendt wrote up the findings in the then well-regarded UNESCO Courier, and this got excerpted in the Irish Times in 1954.
In 1957, the then-new magazine New Scientist mentioned it. By the end of the 1950s, anyone who read a newspaper could have been aware of the basic idea.
Throughout the 50s and 60s, US, Swedish, German and Soviet scientists were examining the issue. In 1965, President Lyndon B Johnson even namechecked carbon dioxide build-up in an address to Congress.
By the end of the 1960s, international collaboration was beginning, though there was caution still. For instance, in April 1969, the American scientist Charles Keeling, who had been measuring atmospheric carbon dioxide concentrations at a Hawaiian observatory, revealed that he had been asked to change the title of a lecture from, ‘If carbon dioxide from fossil fuels is changing man’s environment, what will we do about it?’ to ‘Is carbon dioxide from fossil fuel changing man’s environment?’
For climate historians like me, the 1970s are a fascinating period of intense measurement, modelling, observation and thinking which, by the end of the decade, produced a working consensus that there was serious trouble ahead. In effect, Plass had nailed it.
When Plass spoke out, the atmospheric concentration of carbon dioxide was at about 310 parts per million. Today, they are 423 or so. Every year, as we burn more oil, coal and gas, the concentration climbs and more heat is trapped.
By the time Plass’s warning is 100 years old, the concentrations will be much higher. There’s a very good chance we will have gone over the 2 degrees Celsius warming level that used to be regarded as ‘safe’.
By Marc Hudson
Dr Marc Hudson is a climate historian and research fellow in the Science Policy Research Unit at the University of Sussex. He is currently researching the past, present and future of ‘industrial decarbonisation’, especially in the UK.
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