J.R. McNeill
Georgetown University

History does not tell us much of anything directly about social and political responses to climate change. Abrupt climate change is too far back in the past, when societies were too different from our own, to shed any light on the matter. More recent climate change, when societies were more closely comparable to ours, was too gradual, usually too slow to be noticed. Even the arrival the warmer centuries (AD 900-1200) known as the Medieval Optimum and the cooling of the Little Ice Age went undetected at the time.

Widening the lens so as to consider natural shocks of several sorts is more helpful. Such shocks have been part of the ordinary experience of most generations until very recently. The most serious were epidemics and droughts—both of which climate modelers anticipate will become more likely in a greenhouse world. Resilience in the face of such shocks originally consisted mainly of mobility and simplicity, but within the last two centuries came to rest more and more on bureaucratic provisions for disaster and technological means to prevent or mitigate it.

The ability to do this well was (and is) very unevenly distributed around the world. Presuming such shocks become more common in the future, the ability to generate and provide resilience, in whatever form, will become an ever greater force in determining the fates of societies and states. The degree to which international institutions master the necessary skills and execute them reliably and equitably will play an ever larger role in determining the levels of tensions within the international system.

The demographic and economic effects of nature’s shocks, while often locally or regionally devastating, normally came to little on the global scale. The plague pandemic of the 14th century is the greatest exception. Sizeable shocks, in propitious circumstances, could have serious politically disruptive and destabilising effects within societies and occasionally contributed to conflict between societies. Nature’s shocks also routinely nudged along processes of social change, and occasionally more than that, notably in the field of religion.

On the record of the past, one should expect a greenhouse world to be more volatile politically, with stable nation-state regimes harder to build and maintain; and internationalism subject to strains somewhat greater than would otherwise be the case, but with a significant counter-current pushing towards greater cooperation in the face of common threats. And one should expect stronger religious enthusiasm than has ordinarily prevailed in modern history.