Just so y'all know, there's no possible moral argument for developed countries rejecting migrants as the climate change situation escalates.

If you believe in collective, societal moral responsibility, then we're collectively morally culpable for causing anthropogenic climate change and therefore have a collective moral obligation to handle its worst effects.

If you don't believe in collective, societal moral responsibility, then we're not collectively morally responsible for creating the incredible systems that make wealth accumulation possible in rich countries. In that case, we're no more morally entitled to the benefits of being a rich country than they are, and we have a duty to share those benefits with everyone else.

I, personally, am in the latter camp, but the point is, you can't have it both ways.