Indeed, this specific sentence seems a bit odd.

However, if there is one thing we're not lacking, it's crisis zones, where people are desperate to move away from if given half a chance. Given both the current rate of climate change and the current political climate, this is bound to increase, even after the global population peak.

So I suspect that a lack of migrants willing to resettle to unaffected/less affected regions will not be a problem for the next few decades.