Sixty years ago, on this day, November 23rd 1965, American scientist Walter Orr Roberts gave a speech. In it, this –
“Perhaps, through this mechanism, we are already modifying the atmosphere, unknowingly and on a large scale, as we clearly are already doing on the city scale. Indeed, can we be sure that city-scale modification is simply city-scale? Or are the atmospheric solids and gases put in over the city bringing changes on a larger scale? The relative abundance of carbon dioxide is clearly rising in the atmosphere, almost certainly through man’s intervention. But no one seems at all secure about what this is doing to the climate.”
Bulletin of the American Meteorological Society Vol. 47, No. 3, March 1966 Based on an address delivered at the International Symposium on Electromagnetic Sensing of the Earth from Satellites, Miami, Fla., 23 November 1965.
The amount of carbon dioxide in the air was 320ppm. As of 2025, when this post was published, it was 430ppm. This matters because the more carbon dioxide in the air, the more heat gets trapped. The more heat, the more extreme weather events. You can make it more complicated than that if you want, but really, it’s not. Fwiw, I have a tattoo of the Keeling Curve on my left forearm.
The broader context was since the early 1950s the question of carbon dioxide build-up and its possible climatic consequences had been known. Not necessarily taken seriously, but by the mid-1960s, this was -just- beginning to shift.
The specific context was Roberts gave his speech in the aftermath of the release of the PSAC report on November 7th 1965.
What I think we can learn from this – it wasn’t secret or arcane information. I am not saying “everyone knew” but, well, a lot of people did.
What happened next – the emissions kept climbing. NCAR kept investigating.
What do you think? Does this pass the ‘so what?’ threshold? Have I got facts wrong? Interpretation wrong? Please do comment on this post, unless you are a denialist, obvs.
Also on this day:
November 23, 1961 – “The Day the Earth Caught Fire” (in Denmark)
November 23, 1963 – Doctor Who begins
November 23, 1968 – “Hell upon Earth” warning about environmental destruction,inc. Climate…
November 23, 1988 – Australian Prime Minister Bob Hawke gives greenhouse speech
November 23, 2009 – Global Warming Policy Foundation launched