Keith Poole has spent years devising measures of political ideology. The late Phil Frickey and I used his scholarship in our work on public choice theory. He has now produced similar information about Presidents, incorporated in the following chart:
It would be useful to have a similar measure for environmental policy. The early part of the graph would look much different. Until Reagan, the differences between Democrats and Republicans on environmental story were fairly modest. On the Republican side, the rankings between Reagan, Bush I, and Bush II seem about right, although the gap between Bush I and the other two on this issue is probably larger than the chart indicates.
What about the Democratic side? The chart ranks Carter as the most liberal of the post-1970 Democrats, followed by Clinton, and then Obama. It’s hard to know how to rank these three in terms of environmental issues. The environment was not a core issue for any of them, including Obama. My own impression is that Obama has implemented more significant new regulations than the other two, but this was at least partly because of an eight-year backlog of legally mandated rules during the Bush Administration. That includes the climate change regulations mandated by the Supreme Court.
In terms of the environment, then, I’d cluster the three post-1975 Democrats together, put Bush II and Reagan well on the other side, and put Bush I in the middle. But that’s just an impression, not the kind of careful measurement used by Poole and his fellow researchers.