The latest UN report on species extinctions – climate change’s “nuclear winter?”

Print and virtual media have been abuzz these past several days with the rollout of a new United Nations report suggesting that around a million species of animals and plants face extinction worldwide as a result of human activity. The report goes further, linking that species loss to reduced quality of life and perhaps even threatening human existence itself.  

Big news indeed.

But perhaps not really new? Scientists have been studying and reporting on human-caused reductions in biodiversity and associated declines in ecosystem services for as long as any of us can remember (think Endangered species Act).

Reminiscent of events a third of a century ago, with respect to the nuclear threat. During the Cold War years[1] (dating from the end of World War II through the collapse of the former Soviet Union), the general public rated nuclear conflict as one of its greatest concerns. But such concerns spiked in 1983 when Carl Sagan and co-authors added nuclear winter (a period of abnormal cold and darkness posited to result from a nuclear war, as it produced layers of smoke and dust in the atmosphere blocking the sun’s rays) to the list of impacts.

At the time, the great groundswell of public concern seemed puzzling. Here nuclear warfare threatened wholesale loss of civilian populations, resulting directly from bomb blasts in urban areas, followed by radiation sickness and decades of mutations and cancers for the survivors. Who needed to hear more? Wasn’t that enough to prompt calls for disarmament and peace? But for many people, the threat of cold, darkness, crop failures for months or years was the last straw.

Even early on, it seems that the current UN report, by virtue of the immense and widespread species loss it documents and the way it explicitly links that species loss to decline in human prospects, may have touched a similar public nerve. Perhaps this will prove to be the tipping point, coming on top of the other United Nations products – the periodic IPCC Assessment Reports, and special IPCC reports on extreme events and hazards, the difference in impacts between 1.50C and 20C of warming – that builds the level of public support needed to spur international action.

 We can only hope.


Speaking of hope, some might have noticed in the fine print that the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (commonly called the IPBES), which compiled the assessment, is chaired by none other than Sir Robert Watson. That’s the same Bob Watson who played a pivotal role in standing up the U.S. Global Change Research Program three decades ago (and, even earlier, giving the world’s ozone protocols a positive push) while working at NASA. He would come into interagency  planning meetings back then and instantly energize the room. Early-career geoscientists take note: this is proof of the importance of enthusiasm, insight, and staying power.

Good on you, Bob!



[1]And even since. Today those concerns get the occasional boost as tensions mount between the U.S. and Iran or North Korea, or the Middle East roils, or India and Pakistan get ructious.  

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