I admit to some hyperbole here. The negative effects of the ersatz process are qualitatively different from burning plastic. I was just using it as a sort of analogy for really really stupid behavior ("throwing money on the fire"; "burning plastic." maybe it doesn't work as a maxim.)
In my honest opinion, the ersatz process enacted in the 1970s, would be
significantly worse for the environment than that.
Right now, IOTL, the fragilest of political coalitions is forming in the US between national security hawks, environmentalists, energy and extraction industry corporate interests, and labor (especially miners' unions and farmers.) This coalition has just started examining energy issues, noting that it would be a good idea for us to develop alternatives to petroleum for the various reasons held dear by each specific faction (job security, money, saving the planet, oil is owned by "terrorists", what have you.)
If in the 1970s you develop an economic model whereby a profit can be made from ersatz oil (and let's add in ethanol, since any change in energy policy is going to have to go through the farm belt) you've derailed that coalition preemptively. Organized labor and farmers are as happy with the way things are as the corporate interests are, and the Hawks couldn't care less about fossil fuels so long as they're not in the pockets of the Saudis anymore.
Meanwhile you're pumping much more carbon into the atmosphere than IOTL and environmentalism has even less political support. It's popular support probably remains steady, perhaps even rises a few percentage points nationally, but not enough to get any significant legislation passed.
So while it's possible that as
1940LaSalle suggested that science might have caught up and cleaned up the process in the intervening decades, it's doubtful, because the public will to call for its clean-up probably wouldn't be there.
If, ITTL, people begin to think environmentally in the '00s in significant enough numbers to call for change, as they did IOTL, it's probably too late. In 2008 we're probably looking at the equivalent of OTL unchecked 2030-2050 carbon levels with legislation stuck back in the 1990s.
That's what I mean by catastrophe
