COVID-19 is not a climate-change pandemic — as far as we know, nothing about the emergence or spread of the coronavirus bears the recognizable imprint of global warming. But if the disease and our utter inability to respond to it terrifies you about our future … it should. Not just as a “fire drill” for climate change, generally, but as a test run for all the diseases that will be unleashed in the decades ahead by warming.

The virus is a terrifying harbinger of future pandemics that will be brought about if climate change continues to so deeply destabilize the natural world: scrambling ecosystems, collapsing habitats, rewiring wildlife, and rewriting the rules that have governed all life on this planet for all of human history.

Among the many unnerving lessons the two crises share is this one:

Nature is mighty and scary. We have not defeated it but live within it, subject to its temperamental power, no matter where it is that you live or how protected you may normally feel.

COVID-19 is one such hazard we believed, until a few weeks ago, we were mostly invulnerable to. In the future, we may have to reckon also with diseases we believed we already defeated, since in addition to bringing about pandemics of the future, global warming will revive plagues of the past.


There are now, trapped in Arctic ice, diseases that have not circulated in the air for millions of years — in some cases, since before humans were around to encounter them. Which means our immune systems would have no idea how to fight back when those prehistoric plagues emerge from the ice. Already, in laboratories, several microbes have been reanimated: a 32,000-year-old “extremophile” bacteria revived in 2005, an 8-million-year-old bug brought back to life in 2007.

The Arctic also stores terrifying diseases from more recent times. In Alaska, researchers have discovered remnants of the 1918 flu that infected as many as 500 million, and killed as many as 50 million — about 3 percent of the world’s population. Scientists suspect smallpox is trapped in Siberian ice, among many other diseases that have otherwise passed into human legend. Many of these frozen organisms won’t actually survive the thaw … But in 2016, a boy was killed and 20 others infected by anthrax released when retreating permafrost exposed the frozen carcass of a reindeer killed by the bacteria at least 75 years earlier; more than 2,000 present-day reindeer died.

What concerns epidemiologists more than ancient diseases are existing scourges relocated, rewired, or even re-evolved by warming … Malaria, for instance, thrives in hotter regions, which is one reason the World Bank estimates that by 2030, 3.6 billion people will be reckoning with it — 100 million as a direct result of climate change.

Projections like those depend not just on climate models but on an intricate understanding of the organism at play. Malaria transmission involves both the disease and the mosquito; Lyme disease, both the disease and the tick — which is another epidemiologically threatening creature whose universe is rapidly expanding, thanks to global warming.

Overall, the number of disease cases from mosquitoes, ticks, and fleas have tripled in the U.S. over just the last 13 years, with dozens of counties across the country encountering ticks for the first time … Lyme is still, in relative terms, a young disease, and one we don’t yet understand all that well. We do know ticks, however, as surely as we know malaria — there are not many parasites we understand better. But there are many, many millions we understand worse, which means our sense of how climate change will redirect or remodel them is shrouded in a foreboding ignorance.

And then there are the plagues that climate change will confront us with for the very first time — a whole new universe of diseases humans have never before known to even worry about. Scientists guess the planet could harbor more than a million yet-to-be-discovered viruses — many of them, like COVID-19, for now “quarantined” in particular susceptible species, but which could evolve or “jump” into humans, either as the result of changing climatic conditions or because the scrambling of native ecosystems and habitats brings the host species into contact with humans in a much more direct way than ever before.

The more we pave over and log and deforest the natural world, disrupting stable ecosystems and turning those organisms living happily within them out into the human world, the more diseases, and pandemics, we’ll produce. That is what it means to be living entirely outside the window of climate conditions that enclose all of human history — everything we have ever taken to be stable about our relationship to the planet is thrown into chaos. That chaos will confront us, again and again, with undiscovered disease.

Bacteria are even trickier, and so we probably know about even fewer of them. Perhaps scariest are those that live within us, peacefully for now. More than 99 percent of even those bacteria inside human bodies are currently unknown to science, which means we are operating in near-total ignorance about the effects climate change might have on us.

This essay was adapted from The Uninhabitable Earth: Life After Warming, ( published by Tim Duggan Books in 2019.