At the policy level, there doesn’t need to be a one-size-fits-all solution, but it can be a combination of different factors: add more solar, add more nuclear, increase fuel efficiency, make better dwellings, promote electric cars, research more technologies. Stabilization wedges: https://cmi.princeton.edu/wedges/intro (more like pie slices in that each slice/wedge can be a part of the whole).
Nobody is really calling for primitivism. More like, look at California and its climate initiatives (municipal climate adaptation plans, passenger car fuel economy, cap and trade, renewable energy mandates, EV subsidies, residential code improvements, etc.) It still somehow manages to be one of the world’s biggest economies.
The biggest barrier to climate change action can be summed up in one word: Republicans.
At the individual level, it doesn’t really matter what you do. Fly all you want, eat all the beef you want, just don’t ever vote Republican and actively get them out of office.
Climate change is no longer a scientific or engineering problem. It is a problem of Republican propaganda and corruption of electoral processes. What it is, is a crime against humanity.
If you don’t believe in the participation of federal politics, you can also tackle it (less efficiently) at the state or local levels. That’s what campaigns like the Sierra Club’s Ready for 100 (percent clean energy) campaign is all about: bypassing Republican stonewalling and working directly with local governments to move forward on climate action.
350is another group advocating policy solutions at both the national and local levels. For example, they work with communities to create cleaner grid mixes (the mix of generation technologies used in a given area) through programs like community choice aggregation, which lets ratepayers/voters in an area democratically opt-in to cleaner energy mixes (more renewables, less fossil fuels). These days, the cost increase is minimal to none.
None of this requires primitivism. Most of it isn’t even visible to the average person. The engineering is there. The political will is what’s missing. The Republicans are who’s stopping it.