Thr problem lies not with the leaders, at least not in the western world, people just need to stop voting for conspiracy theorists, it really is that simple.
That is simply not true. No one is on track to meet the Paris agreement goals. This is not because every government is lead by conspiracy theorists.
I think we're suffering from what France suffered from at the beginning of WWI - peacetime generals (or in this case politicians). For the last 30+ years, the consequences for incompetence and fuck ups in politics have been generally low. The current do-nothing political class is a result of these very weak selective pressures. I don't think we'll see a change until more voters begin to feel the effects of climate change and related issues. Hopefully it will be a positive change to more competent leaders, but it's not looking great based on the last few years.