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Who Needs Halloween?

Climate change will bring plenty of tricks and very few treats

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


In 2018, the idea that we need a special holiday to be scared feels a little strange. Zombies, vampires, and werewolves don’t seem so frightening when the real world provides us with Vladimir Putin, white supremacists, and greenhouse gas emissions.  And trust me, as a climate scientist, I’m frightened every day.  Watching our best projections of future climate is like watching a horror movie you can’t walk out of. And the worst part is the willful ignorance of the characters. I mean, who could be so stupid as to walk straight into a house they know is haunted?

We know a little bit about the horrors that await us in the climate haunted house—we did, after all, build it ourselves. Walk in to the entrance. Above the door is that most frightening of instruments—but not just any thermometer. This one is wrapped with a wet washcloth. It’s measuring something called the “wet bulb” temperature: a combination of heat and humidity—a quantity that’s predicted to rise dramatically as the climate changes. When the wet bulb temperature gets too high, it restricts the human body’s ability to cool itself off by sweating. When it exceeds about 80°F, people working outside run the risk of dangerous overheating. When it’s higher than 95°, you—even if you are healthy, lying down, and naked in the shade (and why would you not be?)—will be dead in six hours.

The hallway teems with rats, some the size of human infants. Climate change, it has been pointed out by skeptics, will be good for some species. And this turns out to be true, just not for humans. The shorter winters mean longer breeding seasons for urban rats, and they’re manifestly enjoying themselves. In these increasingly ideal breeding conditions, two rats can, within three years, turn in to almost half a billion.


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The hallway leads back to the kitchen. It’s not well-stocked. Climate change has disrupted the food system. Earlier springs mean blooming fruits are more vulnerable to the occasional frost. Summers are longer, hotter, and drier, causing more crop failure. Heavier downpours carry agricultural runoff to already polluted lakes and rivers. But the most horrifying thing here is the refrigerator. Heat stress and drought associated with climate change have reduced global yields of barley and pushed up prices. There is no beer.

Off the hallway is the living room, where the TV blares news of war, conflict, and massive refugee movements. It’s made worse by the rise of demagogues who exploit even small-scale adversity by blaming large groups of other people. Why did we think “adaptation” to climate change would mean “carefully considering the facts and making sober, scientifically—informed decisions”? Based on historical precedent, that was always a long shot.

Walk through to the bedroom, where you’ll find the greatest horror of all. On the bed lies a person who, at first, looks healthy and serene. But she stares at the ceiling apathetically and does nothing. After walking through the haunted house, she’s too terrified to do anything. She’s never called her representative or senators. She’s never marched or petitioned or organized in her community. She didn’t even vote in the last election. And then you realize: the bedroom is an optical illusion, a hall of mirrors. The person in the bed is you.

We don’t have to live in a horror movie. In fact, if we focus only on scary things, we miss the true meaning of Halloween, which is to force small children into humiliating costumes for our amusement. My own toddler insists that he wants to be “a squid that helps people,” which mystifies his parents and reveals a poor understanding of cephalopod biology. But that kind little squid, and his pirate and dragon and pumpkin and monkey friends, are going to grow up to live in the house we build for them. I think we should at least try to chase the demons out first.

Kate Marvel is a climate scientist at Columbia University and NASA’s Goddard Institute for Space Studies. She received a Ph.D. in theoretical physics from the University of Cambridge and has worked at Stanford University, the Carnegie Institution and Lawrence Livermore National Laboratory. Her writing has appeared in Scientific American, the On Being podcast and Nautilus magazine. Marvel has given talks in places as diverse as comedy clubs, prisons and the TED main stage.

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