[John] Tyndall set out to find whether there was in fact any gas in the atmosphere that could trap heat rays. In 1859, his careful laboratory work identified several gases that did just that. The most important was simple water vapor (H2O). Also effective was carbon dioxide (CO2), although in the atmosphere the gas is only a few parts in ten thousand. Just as a sheet of paper will block more light than an entire pool of clear water, so the trace of CO2 altered the balance of heat radiation through the entire atmosphere.And then:
The next major scientist to consider the Earth's temperature was another man with broad interests, Svante Arrhenius in Stockholm. He too was attracted by the great riddle of the prehistoric ice ages, and he saw CO2 as the key. Why focus on that rare gas rather than water vapor, which was far more abundant? Because the level of water vapor in the atmosphere fluctuated daily, whereas the level of CO2 was set over a geological timescale by emissions from volcanoes. If the emissions changed, the alteration in the CO2 greenhouse effect would only slightly change the global temperature—but that would almost instantly change the average amount of water vapor in the air, which would bring further change through its own greenhouse effect. Thus the level of CO2 acted as a regulator of water vapor, and ultimately determined the planet’s long-term equilibrium temperature.That was in the 1890s. More than a century ago.
The basic idea is that the sun warms the surface of the Earth and the atmosphere (with the above mentioned water vapor and its regulator, CO2) blocked it's dispersal into space. More CO2, more insulation more warmth.
Again this scientific idea has been around more than a century.
And yet this week, Donald Trump's Head (Dismantler) of the Environmental Protection Agency was on CNBC and this happened:
Environmental Protection Agency Administrator Scott Pruitt said Thursday he does not believe carbon dioxide is a primary contributor to global warming.And yet, in reality (a concept the Trump Administration has yet to fully comprehend), the science has been around for more than a century.
"I think that measuring with precision human activity on the climate is something very challenging to do and there's tremendous disagreement about the degree of impact, so no, I would not agree that it's a primary contributor to the global warming that we see," he told CNBC's "Squawk Box."
"But we don't know that yet. ... We need to continue the debate and continue the review and the analysis."