In recent years we've become accustomed to severe weather hitting one part of the planet or another. Drought here, flooding there. Freezing cold fronts in one place, heat waves in another. It was like every country had to take its turn. But what it calamity happened everywhere, all at once?
The U.S. National Academy of Science suggests the whole world may be at risk from simultaneous droughts, famines and epidemics.
The series of papers published by the Proceedings for the National Academy of Sciences (PNAS) shows that policymakers might be underestimating the social and economic consequences of climate change due to insufficient attention on how different climate risks are interconnected.
One paper whose lead author is Franziska Piontek of the Potsdam Institute for Climate Impact Research explores impacts related to "water, agriculture, ecosystems, and malaria at different levels of global warming." The study concludes that: "... uncertainty arising from the impact models is considerable, and larger than that from the climate models. In a low probability-high impact worst-case assessment, almost the whole inhabited world is at risk for multisectoral pressures."
The uncertainties in the model are large enough that they may "mask" the risk of a "worst case" scenario of "multisectoral hotspots," where impacts affecting "water, agriculture, ecosystems, and health" overlap in ways that could affect "all the world's inhabited areas."
In the worst-case analysis, "Almost the entire global population is exposed to multisectoral pressure" at global mean temperatures of around 4C higher, with "roughly 18% of the global population" projected to "experience severe pressure in all four sectors. The affected regions are in Europe, North America, and south-east Asia."