Is there some global movement that wants tighter environmental regulations? Sure. From that it does not follow that anything will ever happen. I would ask you the same questions I asked Dutchy about who, when, and how these regulations will be created, agreed to, monitored, and enforced. But like him, I'm sure you have no answers (then again, Dutchy was worried about the Paris agreement, apparently unaware that aviation was excluded). Calling these details that will magically be worked out is delusional. There is no organization with any authority to create mandatory regulations and enforce them on every nation. You can continue to believe otherwise forever.
You keep repeating the Paris Agreement excluded commercial aviation and shipping emissions. It did. But the exclusion was on the basis ICAO and IMO promulgate a timetable, including self-determined targets, processes and penalties.
Just as with noise pollution, there is no aviation super power able to impose global, standardised rules.
Like noise, implementation will occur on a country by country basis, although increasingly, countries work together. For example, the EU, UK and USA made Chapter 4 / Stage 5 mandatory from 31 December 2017 and 2020 (perhaps why a significant number of older aircraft were withdrawn in 2017), depending on aircraft weight. If airlines don't want to operate to those countries, then don't. If you want to maintain a small compliant sub-fleet, the airlines choice. Or the country is large enough for internal flights. Or if they can be re-purposed for military use.
Within those noise rules, individual countries and airports can set their own charging regimes. For example, a scale of charges for aircraft that barely meet the rules, versus meet by say 5dB-10dB or meet by over 10dB (invented numbers). This can be consistent throughout the day, or greater during the night, or when the airport is busiest, or..............
The difference with noise regulations, especially in the 2 and 3 era, was aircraft manufacturers and airlines were very reluctant followers, because the financial penalties and PR impacts were small. The penalties (no rewards) are still relatively small, though they have outpaced inflation.
For example, the UK uses three bands each for Chapter 3 and 4 (6 in total). Some airports impose no charges. Some only impose charges for 1-2 of the bands. Others, like in London, charge for all six. Not all London airports are consistent. The most expensive to be noisy at is Heathrow, although the financial penalties are small relative to other flight and airport costs.
Even though the penalties are small, where airlines have a choice, guess which airport gets the quieter (cheaper) aircraft?
Increasingly, if an engine type is influential in determining the band, and is just below a more favourable band, you can be sure IAG and the like are pressing the OEM for a PiP, not only for fuel economy, but also a noise improvement, to jump bands. Ask RR for more information on that customer and subject.
The difference between noise and emissions, whether it's motivated by environmental and/social responsibility, favourable PR, cost minimisation, profit maximisation, marketing............. or all of the above, is that proactive airlines and airports seem to be embracing the idea of rewarding and penalising carbon emissions. In fact, I can see airlines, becoming earlier adopters than countries.
The financial margin for being the best versus the worst emitter could in time become quite a significant cost as a percentage of total costs. Not necessarily from day one. And airports could magnify the best and worst margins, if the emissions component of their total charges increases (versus landing/departing, navigation, passenger, parking and other charges).
I'm not going to add any further comment to this thread, as I'm guilty of diverting it from the OP's intent.