My view is that climate change is a world problem. Governments will not oblige their citizens to make steps on their consumption if it means reducing their comfort and their economic power.
Steps should be taken in advance so that once green deals are put in place, countries can implement those effortlessly.
We often hear that some countries don't make enough efforts, but
1. Other countries import carbon emitting products
2. The developed countries of today have emmited greenhouse gases for decades, which allowed them to become developed countries.
The geopolitics of climate change are extremely difficult. I don't think the UN is up for it.
Although a better scenario would be to enact tight regulations on a country basis, but it's a political minefield. Imagine riots because people want to keep using their cars and trade goods that have become illegal, or vendettas against people who emit co2.