City management models today must plan for climate instability. By this, we mean the incompatibility of existing cities with future climate conditions, the understanding of city identity as geographically fixed, and, ultimately, mass climate migrations. Research on the projected geographical shift of the human temperature niche shows that for each 1 degree Celsius of global warming, 1 billion people would be in unsuitably warm areas, which means entire cities will need to migrate. On the positive side, more total land area will be available for human habitation than before, especially in the global north. Unfortunately, Westphalian nation-states have demonstrated an unwillingness to accept mass uncontrolled immigration.
Optimistically, new cities could be created within migration destination countries to realize the economic potential arising from the influx of additional demand and labor, especially as organic reproduction dwindles, while also sidestepping xenophobia triggers from within the existing population. These new cities could not only save millions of lives by opening routes for organized migration, but also be an avenue for a new approach to sharing wealth and resources.