A handy primer:

CO2 levels were steady during these wild swings and throughout the Holocene at roughly 280 parts per million (ppm) until 130 years ago when a stuttering increase to 400 ppm today began. In other words, Holocene temperature changes, and the wild variations that preceded them, were not linked to CO2 changes. This prompts the question: if CO2 changes did not drive these temperature shifts, why all the fuss about CO2 emissions?

The answer owes much to the complexity of the climate system and the wish for simple explanations to explain its variability and with which to make predictions. But climate is not simple. There are many interacting parts that make it a ‘coupled non-linear chaotic system’ in which small variations of any part can create big, unpredictable changes. In the search for something simple to blame, like increasing CO2 levels, this ‘coupled non-linear, chaotic’ nature of climate is often played-down, overlooked or ignored. Things like solar variations, ocean heat transfers, cloud cover and the like – things that may well be the main drivers of climate – seldom get the respect they deserve.

The effect of the sun, the sea and clouds on climate is known and accepted – the Gulf Stream being a well known example – but more precise knowledge suitable for computer models is a different thing altogether. But what can be said for sure, is that the sun, the sea and the clouds are all very important and CO2 is only one player in a big game, not the control knob on the Earth’s thermostat. It is true that CO2 contributes to the greenhouse effect, but its heating effect is small (when compared with water vapour, the main contributor) and drops off logarithmically as its concentration increases. The more there is, the less additional heating effect it has.

It’s almost as though there’s some sort of political agenda that has nothing to do with science or reality.

[Update a while later]

This is interesting: Pruitt doesn’t want to attempt to overturn the endangerment finding:

Pruitt, with the backing of several White House aides, argued in closed-door meetings that the legal hurdles to overturning the finding were massive, and the administration would be setting itself up for a lengthy court battle.

A cadre of conservative climate skeptics are fuming about the decision — expressing their concern to Trump administration officials and arguing Pruitt is setting himself up to run for governor or the Senate. They hope the White House, perhaps senior adviser Stephen Bannon, will intervene and encourage the president to overturn the endangerment finding.

Trump administration officials have not totally ruled out eventually targeting the endangerment finding. Conservative groups have petitioned the EPA to look at reopening it, one source said, and the agency may eventually be compelled to respond to the petition. Axios first reported the news of the petition.

“Getting rid of the Clean Power Plan is just not enough,” said Myron Ebell, the director of the Center for Energy and Environment at the Competitive Enterprise Institute and the former leader of Trump’s EPA transition team.

I agree. It was based on junk science. In fact, they should be trying to get a rehearing of Massachusetts versus EPA when they get Gorsuch on the court.