Here is Carl Sagan testifying to Congress about climate change on December 10, 1985 (see also: C-SPAN source):
Here are a few quotes (all transcription errors are mine):
There are other gases that absorb in the infra-red, many of which have been mentioned already: nitrous oxide, methane, the halocarbons, and these are products, partly of agriculture, fertilizers, refrigeration, aerosol spray cans and so on, all products of our technology. We don’t generate much water into the atmosphere, but we certainly do generate a great deal of carbon dioxide, through the burning of wood and fossil fuels, an apparently benign activity, who could object to humans burning oil, and coal, gas, and wood?
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Now certainly not all aspects of how increased CO2 and other gases into the atmosphere are affecting the climate are known… though the overall picture is quite clear and quite widely understood and accepted… how much increase or decrease in cloudiness is there.. how does that change the albedo and reflectivity of the Earth… it is certainly worthwhile to spend some additional money on research..
[Venus] is an indication of what could happen in an extreme case.
...the best estimates are … at the present rate of burning of fossil fuels, the present rate of increase of minor infra-red absorbing gases in the atmosphere, that there will be a several centigrade degree temperature increase on the Earth, global average, by the middle to the end of the next century, and that has a variety of consequences, including redistribution of local climates and through the melting of glaciers, an increase in sea levels...
So we have a kind of handwriting on the wall … what can be done about it? The idea that we should immediately stop burning fossil fuel, has such severe economic consequences that no one will take it seriously, but there are many other things that can be done. One has to do with subsidies for fossil fuels, more efficient use could be encouraged by fewer government subsidies. Second, there are alternative energy sources, some of which are useful, at least locally. Solar power is certainly one that might be of more general use. Safe fission power plants, which are in principle possible. And then on a longer time scale, the prospect of fusion power. Fission and fusion power plants, in principle, vent no infra-red active gases, and therefore, whatever other problems they may provide, they do not provide a greenhouse problem.
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Here is a problem which transcends our particular generation. … If we don’t do the right thing now, there are very serious problems that our children and grandchildren have to face.
Here is a sense in which the nations, to deal with this problem, have to make a change. … There has to be a trading of benefits and suffering, and that requires a degree of international amity that doesn’t exist today.
Here is Carl Sagan testifying to Congress about climate change on December 10, 1985 (see also: C-SPAN source):
Here are a few quotes (all transcription errors are mine):
Thank you Noah, I added a part of this to the main post.