Insights from past millennia into climatic impacts on human health and survival, por Anthony J. McMichael
Climate change poses threats to human health, safety, and survival via weather extremes and climatic impacts on food yields, fresh water, infectious diseases, conﬂict, and displacement. Paradoxically, these risks to health are neither widely nor fully recognized. Historical experiences of diverse societies experiencing climatic changes, spanning multicentury to single-year duration, provide insights into population health vulnerability—even though most climatic changes were considerably less than those anticipated this century and beyond. Historical experience indicates the following. Long-term climate changes have often destabilized civilizations, typically via food shortages, consequent hunger, disease, and unrest. Medium-term climatic adversity has frequently caused similar health, social, and sometimes political consequences. Infectious disease epidemics have often occurred in association with briefer episodes of temperature shifts, food shortages, impoverishment, and social disruption. (iv) Societies have often learnt to cope (despite hardship for some groups) with recurring shorterterm (decadal to multiyear) regional climatic cycles (e.g., El Niño Southern Oscillation)—except when extreme phases occur. The drought–famine–starvation nexus has been the main, recurring, serious threat to health. Warming this century is not only likely to greatly exceed the Holocene’s natural multidecadal temperature ﬂuctuations but to occur faster. Along with greater climatic variability, models project an increased geographic range and severity of droughts. Modern societies, although larger, better resourced, and more interconnected than past societies, are less ﬂexible, more infrastructure-dependent, densely populated, and hence are vulnerable. Adverse historical climate-related health experiences underscore the case for abating human-induced climate change.
2 - National Centre for Epidemiology and Population Health, Australian National University, Canberra ACT 0200, Australia This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected in 2011. Contributed by Anthony J. McMichael, December 7, 2011 (sent for review September 10, 2011).