> Given economic stratification, collapse is very difficult to avoid and requires major policy changes, including major reductions in inequality and population

> Given economic stratification, collapse is very difficult to avoid and requires major policy changes, including major reductions in inequality and population growth rates. Even in the absence of economic stratification, collapse can still occur if depletion per capita is too high. Mass migration of the poor, who have second and third generations at higher-than-host-normal birthrates sounds like a major trigger of this kind of summary collapse. It both directly increases inequality and secondarily increases inequality by taxing the middle class harder, at the same time it causes a population bloom. Under this HANDY model, the mass migration in response to stalled US population growth could be the proximate trigger for a US social collapse.