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Humanity will outlive climate change and nuclear war, no matter how bad it gets

Local fishermen fish during the sunset, on the Lusiai lake near the small town of Ignalina, some 120km (74,5 miles) north of the capital Vilnius, Lithuania, Saturday, May 18, 2019. (AP Photo/Mindaugas Kulbis)
AP Photo/Mindaugas Kulbis
Humans are capable of unprecedented harm. But one thing we can’t do is extinguish ourselves.
  • Seth Shostak
By Seth Shostak

Senior astronomer, SETI Institute

The young man clearly believed that there would never be another generation of millennials. He expressed the sunny view that long before the year 3,000, Homo sapiens would wipe itself out. “Totally,” to use his vernacular.

I was at a San Francisco salon when he ticked off his chart-topping threats to our existence: climate change, killer viruses, and the ever-popular default, nuclear war. These were not simply worrisome problems, but relentless terrors that will purge us from the planet, he said. Abandon all hope ye who enter the 21st century.

To this I say “chill.” Despite our best efforts, we’re not going to wipe ourselves out.

That’s because apocalypse is well-nigh impossible. We’re like ants: We’re vulnerable to being killed en masse, but the species will survive because, like ants, we’re numerous and dispersed. No matter how many supposedly humanity-ending threats you hurl—literally, in the case of ballistic missiles—humans will continue to crawl the Earth. This comfort may be cold, but it’s still a fact.

Consider the enumerated threats, beginning with a pandemic. A century ago, the Spanish flu caused a staggering 20-50 million deaths, more than WWI. Still, the toll amounted to less than 3% of the world population. As ghastly as it was, the Spanish flu didn’t even rise to the level of decimation; viruses can slay, but they can’t annihilate. If past mortality is prologue, a millennial has less chance of succumbing to a new pandemic than dying in an auto accident.

OK, well what about climate change, now recognized as a non-hoax by 75% of Americans? It’s not the heat per se that will waste us, but the knock-on effects. Low-lying nations will turn into aquariums and Caribbean countries will be pummeled and pelted by savage storms. The economic disruptions will be severe, including ones you might not have considered, such as the damage to your investment portfolio: Five of the world’s 10 largest companies are in the fossil-fuel business.

The World Health Organization estimates that between 2030 and 2050, 5 million people will perish due to the consequences of climate change. Nonetheless, if aliens visit Earth in 2050, they’ll still find billions of humans. Indeed, probably more than walk the planet today.

Despite our best efforts, we’re not going to wipe ourselves out.

OK, but what about the mother of all catastrophes, massive nuclear war? The world’s militaries currently have more than 10,000 nuclear weapons teed up. Let’s dismiss the possibility that diplomacy or common sense will continue to fend off their use, and assume that, one fine day, all adversaries push their respective buttons. Let’s further suppose that only one weapon is dispatched to any particular urban area; that none of the missiles ever misfire or are intercepted; and—just to remain consistently dark—that the bombs are 100% effective, killing each and every inhabitant of the target city and its immediate surroundings. (The actual fraction in Hiroshima was about 30%.)

The simplest and deadliest scenario is that the world’s 10,000 most populous urban areas will be targeted and thoroughly obliterated. This includes all cities the size of Sheboygan, Wisconsin, or larger. Each will witness its own deadly mushroom cloud, and destruction by both blast and radiation.

A rough estimate indicates that the total complement of humans in those 10,000 cities is about 1.6 billion. No one could argue that the death of so many people—more than were alive at the start of the 20th century—would be anything less than an unprecedented horror. But even if the missiles were to fly tomorrow, there would still be 6 billion people on the planet next month. And they could eventually pick up the pieces. The knowledge that built modern society would still be extant. We can’t nuke ourselves back to the Stone Age.

What could end all life on Earth?

That doesn’t mean that we’re in the clear when it comes to the end of humanity—we’re just obsessed with the wrong issues. The millennial’s worry in San Francisco didn’t extend to perils that really could annihilate us. Such threats are real, but they don’t often make the news because their occurrence is not something we control.

Asteroid impacts are one. The dinosaurs and most other less-charismatic land dwellers were snuffed out 66 million years ago by an incoming asteroid that was five-miles wide. It’s a sure bet that sooner or later one of its bouldery brethren will slam into Earth once more, releasing thousands of times more energy than the totality of our nuclear weapons.

Fortunately, death-by-asteroid is something we can see coming and do something about. Various technologies have been proposed. Some involve deploying rocket-powered craft to spoil the asteroid’s aim, and others are as simple as painting one side of the rock white and letting the pressure from sunlight gently deflect it from hitting our world.

However, there’s at least one lethal bullet we might never be able to dodge: a gamma ray burst. This cosmic phenomenon could sterilize our planet in short order. Such bursts are not frequent—they’re thought to be the final gasps of collapsing, massive stars—but if one were to occur in our own galaxy, the results could be truly catastrophic, resulting in destruction of our protective atmosphere. There would be no warning of such an event. But although lethal, nearby gamma-ray bursts are also very rare. We might never see such an event in all the future history of humankind. At least, you can hope for that.

The millennial dystopian attitude is not totally illogical. The problems we confront in this century are menacing, and they won’t solve themselves. But a resort to the logic of “it doesn’t matter what we do because we’re all doomed anyway” is both lazy and wrong.

There’s little doubt that Homo sapiens is capable of unprecedented harm. But one thing we can’t do is extinguish ourselves—we’ll have to leave that achievement to an outside celestial force.

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