Im sure the ecology is much improved by letting people stay where they are and be poorer. In fact we should start to remove people from all rich places so the can live in sustainable poverty.
Leaving those climate refugees where they are wouldn't mean they were poor, it would mean they were dead. There are all kinds of irrational extreme positions that would maximize environmental protection. Certainly the best thing we could do for the environment would be to kill ourselves off, but very few people would argue for that. Instead it's better to go for something more balanced and limiting the number of people coming in your country to an amount the land can sustainably support seems pretty reasonable.
> to an amount the land can sustainably support seems pretty reasonable
Is the land in refugees home countries better able to sustainably support the populations on average, whether moving because of climate, lack of a way to support the people, etc?