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Projections like those depend not just on climate models but on an intricate understanding of the organism at play. Or, rather, organisms. 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. As Mary Beth Pfeiffer has documented, Lyme case counts have spiked in Japan, Turkey, and South Korea, where the disease was literally nonexistent as recently as 2010—zero cases—and now lives inside hundreds more Koreans each year. In the Netherlands, 54 percent of the country’s land is now infested; in Europe as a whole, Lyme caseloads are now three times the standard level. In the United States, there are likely around 300,000 new infections each year—and since many of even those treated for Lyme continue to show symptoms years after treatment, the numbers can stockpile. Overall, the number of disease cases from mosquitoes, ticks, and fleas have tripled in the U.S. over just the last thirteen years, with dozens of counties across the country encountering ticks for the first time. But the effects of the epidemic can be seen perhaps most clearly in animals other than humans: in Minnesota, during the 2000s, winter ticks helped drop the moose population by 58 percent in a single decade, and some environmentalists believe the species could be eradicated entirely from the state as soon as 2020. In New England, dead moose calves have been found suckling as many as 90,000 engorged ticks, often killing the calves not through Lyme disease but simple anemia, the effect of that number of bugs each drawing a few milliliters of blood from the moose. Those that survive are far from robust, many having scratched so incessantly at their own hides to clear it of ticks that they completely eliminated their own hair, leaving behind a spooky gray skin that has earned them the name “ghost moose.”
Lyme is still, in relative terms, a young disease, and one we don’t yet understand all that welclass="underline" we attribute a very mysterious and incoherent set of symptoms to it, from joint pain to fatigue to memory loss to facial palsy, almost as a catchall explanation for ailments we cannot pinpoint in patients who we know have been bitten by a bug carrying the bug. 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.
“New universe” is not hyperbole. Scientists guess the planet could harbor more than a million yet-to-be-discovered viruses. 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 presently unknown to science, which means we are operating in near-total ignorance about the effects climate change might have on the bugs in, for instance, our guts—about how many of the bacteria modern humans have come to rely on, like unseen factory workers, for everything from digesting our food to modulating our anxiety, could be rewired, diminished, or entirely killed off by an additional few degrees of heat.
Overwhelmingly, of course, the viruses and bacteria making homes inside us are nonthreatening to humans—at present. Presumably, a difference of a degree or two in global temperature won’t dramatically change the behavior of the majority of them—probably the vast majority, even the overwhelming majority. But consider the case of the saiga—the adorable, dwarflike antelope, native to central Asia. In May 2015, nearly two-thirds of the global population died in the span of just days—every single saiga in an area the size of Florida, the land suddenly dotted with hundreds of thousands of saiga carcasses and not one lone survivor. An event like this is called a “mega-death,” this one so striking and cinematic that it gave rise, immediately, to a whole raft of conspiracy theories: aliens, radiation, dumped rocket fuel. But no toxins were found by researchers poking through the killing fields—in the animals themselves, in the soil, in the local plants. The culprit, it turned out, was a simple bacteria, Pasteurella multocida, which had lived inside the saiga’s tonsils, without threatening its host in any way, for many, many generations. Suddenly it had proliferated, emigrated to the bloodstream, and from there to the animals’ liver, kidneys, and spleen. Why? “The places where the saigas died in May 2015 were extremely warm and humid,” Ed Yong wrote in The Atlantic. “In fact, humidity levels were the highest ever seen in the region since records began in 1948. The same pattern held for two earlier, and much smaller, die-offs from 1981 and 1988. When the temperature gets really hot, and the air gets really wet, saiga die. Climate is the trigger, Pasteurella is the bullet.”
This is not to say we now understand what precisely about humidity weaponized Pasteurella, or how many of the other bacteria living inside mammals like us—the 1 percent we have identified, or perhaps more worryingly the 99 percent we house without any knowledge or understanding—might be similarly triggered by climate, friendly, symbiotic bugs with whom we’ve lived in some cases for millions of years, transformed suddenly into contagions already inside us. That remains a mystery. But ignorance is no comfort. Presumably climate change will introduce us to some of them.
Economic Collapse
The murmuring mantra of global markets—which prevailed between the end of the Cold War and the onset of the Great Recession, promising something like their own eternal reign—is that economic growth will save us from anything and everything.
But in the aftermath of the 2008 crash, a number of historians and iconoclastic economists studying what they call “fossil capitalism” have started to suggest that the entire history of swift economic growth, which began somewhat suddenly in the eighteenth century, is not the result of innovation or the dynamics of free trade, but simply our discovery of fossil fuels and all their raw power—a onetime injection of that new “value” into a system that had previously been characterized by unending subsistence living. This is a minority view, among economists, and yet the précis version of the perspective is quite powerful. Before fossil fuels, nobody lived better than their parents or grandparents or ancestors from five hundred years before, except in the immediate aftermath of a great plague like the Black Death, which allowed the lucky survivors to gobble up the resources liberated by mass graves.
In the West especially, we tend to believe we’ve invented our way out of that endless zero-sum, scratch-and-claw resource scramble—both with particular innovations, like the steam engine and computer, and with the development of a dynamic capitalistic system to reward them. But scholars like Andreas Malm have a different perspective: we have been extracted from that muck only by a singular innovation, one engineered not by entrepreneurial human hands but in fact millions of years before the first ones ever dug at the earth—engineered by time and geologic weight, which many millennia ago pressed the fossils of Earth’s earlier carbon-based life forms (plants, small animals) into petroleum, like lemon under a press. Oil is the patrimony of the planet’s prehuman past: what stored energy the earth can produce when undisturbed for millennia. As soon as humans discovered that storehouse, they set about plundering it—so fast that, at various points over the last half century, oil forecasters have panicked about running out. In 1968, the labor historian Eric Hobsbawm wrote, “Whoever says Industrial Revolution, says cotton.” Today, he would probably substitute “fossil fuel.”