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The Slow Horror of Climate Change Infertility

The horrors of global warming have been depicted through flames, melting ice, monsoon floods and whipping winds, but the question of fertility is the one that looms largest for humanity

You can see the smoke from space. It looks like wisps of cotton stuck on a branch, floating toward the blue of the sea. On the ground, amid the actual flames and swirling winds, there’s nothing but orange, in all shades: tangerine flames, brick-hued sky and a bloody, hazy horizon.

Many animals are dying in this hellfire, with nowhere to go and little relief as the disaster in Australia rages forth. Wildfires can spread at nearly 7 miles per hour in forests and an astonishing 14 miles per hour in grasslands, ravaging animal habitats and consuming generations whole. The creatures in Australia are famously tough, having evolved in a land of extremes. It’s just the human touch, really, that’s erased entire species over the last 200 years in this massive island continent. With the specter of accelerating climate change and catastrophes like the ongoing fires, scientists fear upwards of 30 percent of existing species could be “committed to extinction” by 2050.


The tragedy is obvious, even if you haven’t seen images of dead marsupials lining the freeway; one estimate suggests half a billion animals have been affected in Australia so far. What’s less clear, however, is how human-driven climate change will impact whether survivors can continue bloodlines. Experts say that we need more info, stat, on how a warming ecosystem can hurt a species’ ability to reproduce. But what we know so far paints an alarming picture — for humans, not just other animals.

“Currently, the information we have suggests this will be a serious issue for many organisms. But which ones are most at risk? Are fertility losses going to be enough to wipe out populations, or can just a few fertile individuals keep populations going? At the moment, we just don’t know,” Tom Price, evolutionary biologist at the University of Liverpool, wrote in a scientific journal op-ed last year.

The horrors of climate change have been depicted through flames, melting ice, monsoon floods and whipping winds, but the question of fertility is the one that looms largest for us. Humans are clever enough to evacuate and take shelter in more effective ways than the average mammal, but even we can’t outrun the effects of heat on our literal balls.

Aquatic species and cold-blooded animals are most vulnerable to the impacts of climate change, but mammals are highly sensitive, too. Especially in the testicles, which usually hang outside of male mammalian bodies because body heat kills sperm. Turns out, this is critical: Heat stress makes males infertile before females, according to research from the University of Lincoln.

This isn’t just a problem in environments with future rising temperatures, but rather a part of current fertility patterns in the U.S. Even a balmy summer heat wave can make men shoot blanks, as a UCLA researcher discovered by reviewing annual birth rates. Environmental economist Alan Barreca observed that this dip in fertility happens across the country, in different climates, even despite evidence that people have more sex when it gets warm. This is a real problem given that we’re headed toward serious underpopulation issues, which could slow economic growth in ways that decimate the “middle class” and those in poverty. Americans had fewer babies in 2017 than any year since 1978. And looking at the culture, it doesn’t appear that’ll dramatically change anytime soon.

We’re already choosing to not have kids because we don’t want to bring them into a world that’s spiraling toward ecological and economic disrepair. Couple that with the damage climate change can and will do to home values, prices of goods, development, job growth and beyond, and it’s easy to see why we’re facing some deep, systemic issues without much recourse visible. Some nihilists will suggest that “overpopulation” is the climate problem, actually, and that us going infertile and sinking into a nice, long Great Depression 2.0 is partly just Mother Earth’s correction. Except researchers all say that’s not really true. We really need to be having kids. (And even if a couple can get pregnant, they’ll have to deal with the danger of heat stress hurting fetuses in the womb.)

One of the cruelest twists of all is that this infertility problem won’t affect all societies equally. New research last year suggested that global temperature increases will disproportionately hurt poorer countries, which usually rely on agriculture to support the working class. Scarcity of goods would lead to higher prices, and ultimately, a change in labor demands (i.e., a need for more manual workers). “Our model showed that climate change decreases the return on acquiring skills, leading parents to invest fewer resources in the education of each child, and to increase fertility,” wrote researcher Soheil Shayegh of Bocconi University in Milan.

People in developed nations like the U.S. wouldn’t have the same economic pressure, lowering our birth rates, and allowing a smaller pool of kids to have more resources like education. “This is particularly poignant, because those richer countries have disproportionately benefited from the natural resource use that’s driven climate change,” co-author Gregory Casey, of Williams College, observed.

The slow horror of mysteriously not being able to have kids, even when you desperately want one, is a stark contrast from the images of climate change consequences we normally see. There will be no train a la Snowpiercer, and no tidal waves like the ones seen in The Day After Tomorrow. But scientists are racing to find more data on infertility because of the profound way birth shapes the fabric of both society and the individual. Perhaps just a handful of fertile individuals can technically keep other mammalian species going, as some biologists suggest. Certainly, that process will help rebuild some ecosystems in Australia, even as the lands burn into a charred, cracked crust. But having a child is so much more than survival for humans, and to lose that brings unique pain.

There will be no massive storm to point to as the source of destruction. Just a string of too-warm days, and the sinking feeling that it can’t be fixed.