>Most political systems have two main parties competing for power

I disagree. While this is true for some (US, UK), it's not true for other democracies (Spain, Germany), and even less true for more authoritarian systems (Russia, China). Some countries have political systems that are actually able to make long term decisions.

>Although both parties broadly agree that climate change is bad

True in some places, but not in others, such as Russia, Brazil, or (most importantly) the US.

While I agree that decarbonization is really hard, and in part due to the reasons you listed, they are also not as universal as you paint them out to be.