The reason China, Australia and India gets away with what they are doing without sanctions is because they are pointing at the US and saying "they get away without doing anything so why shouldn't we?". That creates a form of international stalemate because no one can form the necessary coalition required for the agreements to have any sort of economical and political teeth.

I think that's just wishful thinking, honestly. There wouldn't be a significant change even if the US got it's act together. They'd just use different excuses

Obviously, but having US onboard opens up possibilities to create incentives that credible international accords are built on.

Or the other way around, without the US, China and Australia, even if the rest of the world does everything right, global carbon dioxide levels will not only keep increasing, but do so in an accelerating manner.

And before you ask why not China could create credible incentives for the US, the answer is that they do not have the institutions for it, which the US has. At least in theory.

The possible solution is for the world to place limits on making, buying, and selling things. Use less, buy less, travel less, mend your own clothes, grow some of your own food (if possible), be able to repair and use your device for 20 years, turn off your devices at night, use mass transit, don't use the AC, buy furniture that lasts for decades, etc.

That won't happen because of an economic collapse and no politician would ever get elected with this thinking (at least in the US). Plus, you've now taken away many freedoms that are inherit in democratic societies.

To me green technologies are better than nothing but there's really a consumption problem. And I'm completely guilty of it as well.

You're right. The average voter considers carbon tax, very high VAT, and scaling back of mass consumer good production indistinguishable from poverty. Airline flights in the US used to cost a month's salary before deregulation.