My biggest concern with these single attribute solutions is that they might lead to a sense of complacency about CO2 emissions. This could lead to an even bigger problem with ocean acidification than there would have been otherwise.
As for making people complacent: they're already complacent. I include almost everybody in that. The Paris agreement is unrealistic, lacks enforcement, and most countries are well behind their modest targets. Germany is increasing CO2 emissions because they're shutting down their nuclear plants. Etc, etc.
Maybe what makes good people complacent is watered-down, sugar-coated plans for fixing the climate. Just plant trees, put some solar on your roof, turn down your thermostat, we'll be fine. Maybe it would shake them out of complacency if we showed them what it would actually take to get us out of the mess we're in.
We know what to do: stop burning carbon, we have the technology today to replace carbon energy, we just want to do it as cheaply as possible without disrupting the Koch brother's revenue stream.