Wrong policy, they should aim for a 0.2% population decrease over the next 200 years and then stabilize their popuplation at a significantly lower level. How many children a couple has is not relevant, as long as the overall population still shrinks enough and it should shrink - massively.
After 2035 world population likely goes into a completly natural shrinking process that is far greater than the 0.2% suggested till mankind reaches a fully sustainable level. Without immigrations, most developed countries would already be in a shrinking process.
So far the whole climate discussion excludes overpopulation, although this would be by far the best way and sustainable way benefitting 99% of all living creatures. It really doesn't hurt a single person if you aim for a birth rate below 2.