seed clever person It evolved about 300,000 years ago and came to rule the Earth unlike any species before it. But how long can humans live?
Humanity will eventually perish. At the most optimistic estimates, our species will probably survive another billion years of her life, ending when the Sun’s expanding crust bulges outward and heats the planet to Venus-like conditions.
But a billion years is a long time. A billion years ago, life on Earth consisted of microbes. Multicellular organisms appeared about 600 million years ago, when sponges proliferated. One of his modeling studies in 2021 natural earth science It suggests that the Earth’s atmosphere would have had little oxygen by then, suggesting that anaerobic microbes, not humans, would likely be the last living Earthlings.
Given that surviving to watch the sun burn the earth down is a daunting task, when are humans likely to face doom? , says Henry Gee, a paleontologist and senior editor at the journal. Nature, working on a book about the extinction of the human race. It rejuvenates the human race. But Gee doesn’t think these rules always apply. H. Wise
“Humans are a rather exceptional species,” he says. “We may live for millions of years, or we may all fall next week.”
Doomsday opportunities abound. Humanity could be wiped out by a catastrophic asteroid impact, self-destruct in a global nuclear war, or succumb to the climatic emergency. But humans are a hardy bunch, so the most likely scenario is a combination of catastrophes that could wipe us out completely.
choose your poison
Some species of killers are beyond our control.In a 2021 paper in the journal IcarusFor example, researchers explain that asteroids comparable to the 10- to 15-kilometer-diameter asteroids that wiped out non-bird dinosaurs hit Earth about every 250 to 500 million years. In a preprint paper posted on the server arXiv.org, physicists Philip Rubin and Alexander Cohen argue that given a six-month warning and an arsenal of nuclear weapons to blow away, humans will likely kill dinosaurs. We calculate that it will have the ability to defend against asteroids the size of space rocks to harmless pebble clouds. Rubin and Cohen suggest that if there are fewer warnings or bigger asteroids, humanity should give up and “party” or “move to Mars or the Moon and party.” The largest asteroid that scientists currently know could hit Earth is called (29075) 1950 DA. With a diameter of just 1,300 meters, it has a 1 in 50,000 chance of colliding with Earth in March 2880, according to a 2022 risk analysis by the European Space Agency.
Arriving universes aside, many threats to humanity are of our own creation, including nuclear war, climate emergency, and ecological collapse. As some AI critics have suggested, our own technology may overwhelm us in the form of a sentient artificial intelligence that decides to obliterate its creators.
A full-scale nuclear war could easily wipe out humanity, says François Diaz Maurin, deputy editor for nuclear issues at the Bulletin of the Atomic Scientists. The last time humanity dropped nuclear bombs on each other, the United States was the only one with nuclear warheads, so there was no danger of nuclear retaliation. Not today. Bombs are much bigger. These bombs, which hit the Japanese cities of Hiroshima and Nagasaki in 1945, packed the equivalent of 15 and 21 kilotonnes of TNT, respectively. Together, an estimated 110,000 to 210,000 people died. For example, if a 300-kiloton nuclear weapon were dropped on New York City today, he would kill a million people in 24 hours, Diaz-Morin says. A regional nuclear war, such as that between India and Pakistan, could kill 27 million people in the short term, while an all-out nuclear war between the United States and Russia would directly kill an estimated 360 million people. He added that it could cause the death of
The threat to human existence itself will come after war, when soot from massive fires ignited by bombing rapidly alters the climate in a scenario known as nuclear winter. The scare of a nuclear winter may have receded since the end of the Cold War, Diaz-Morin says, but studies show the environmental impacts are severe. Even a regional nuclear war would destroy the ozone layer, block sunlight, and reduce precipitation globally. Over 5 billion people could die in just two years.
“The possibility of destroying humanity is still real,” says Diaz-Morin.
Deaths from ecological pollution and climate emergencies will be slower, but still within the realm of possibility. Humans are already facing health stressors from chronic pollution, exacerbated by the heat of summer. As temperatures rise, people have to breathe faster to expel the warmth, and more pollution gets into their lungs. The climate emergency also exacerbates existing problems with food security. For example, prolonged drought can devastate agricultural land and exacerbate infectious diseases. “Climate change, health inequalities, and inequalities in general are interrelated and impacting our global population,” says Richtveld.
perfect storm
Will these inequalities ultimately lead to the downfall of entire species? is not easy. But it’s probably not practical to consider risks in isolation anyway, says Kemp.
“When you look back at history, like mass extinctions and social collapses, it didn’t happen just once,” says Kemp. “If you’re going to rely on a single silver bullet to kill everyone in a single event, you have to write science fiction.”
The end of humanity is much more likely to be driven by multiple factors, says Kemp. Apocalyptic movies often use viruses, bacteria, and fungi to wipe out vast swaths of the population, but the immune system is such a broad and effective defense that a pandemic alone could drive humanity to extinction. The Black Death killed 30 to 50 percent of Europe’s population, but the pathogen is unlikely to kill all of humanity, said Adalja. says. “Yes, infections can kill a lot of people,” he says. [of people] Resilient and able to survive. “
Humans also have tools to fight pathogens, Adalja said. From treatments to vaccines to social distancing measures that have become widely known around the world during the COVID pandemic. There is one example of a mammal that may have been completely wiped out by an epidemic, he says: the Christmas Island rat (Rattus macleari), an endemic island species that may have gone extinct due to a parasite invasion, also called Maclear’s rat.
“We’re not helpless like the Christmas Island rats who couldn’t escape that island,” says Adalja. “We have the power to change destiny.”
If infectious diseases contribute to human extinction, it could be just one piece of a larger puzzle. Imagine the world being upended by the disruption of agriculture due to rising sea levels and climate change. Humans in this climate-ravaged world try geo-engineered solutions that don’t work. Things get worse. Resources are scarce and many countries have nuclear weapons. By the way, in this scenario, yellow fever-carrying mosquitoes now live as far north as Canada. According to Kemp, it’s not hard to see how populations could decline and disappear in the face of different challenges.
Worst-case scenarios have not been well studied, says Kemp. For example, in climate science, much work has been done on what the world would look like if it warmed 2-3 degrees Celsius above the pre-industrial average, but what would the world look like if it warmed 5-6 degrees Celsius above the pre-industrial average? has been little studied. This is partly because scientists have a hard time predicting impacts of such warming, and partly because climate scientists feel pressure from politicians to stay off guard. Yes, Kemp says. Future worst-case scenario models also tend to do a poor job of predicting the cascading effects of disasters. “The general field of existential risk is relatively new, emerging, and understudied,” he says.
There is a question of how much humans should worry about a big picture like extinction. Controversial tech billionaires such as Elon Musk and Peter Thiel have funded organizations dedicated to studying the risks of transformative technology, and some see the issue as pressing. But some would argue that today’s issue is urgent enough. According to Sarah Cornell, a global sustainability researcher at the Stockholm Resilience Center, humans are already heating the planet, abusing and destroying nature, and using land and water unsustainably. , says it produces chemicals that are toxic to all life and often serves the wealthiest people in the world. at Stockholm University.
“Today’s reality is that some humans undermine and even destroy the living conditions of so many others,” Cornell says. “From a human scale perspective, this is already an existential crisis, not a future risk.”
