How will humanity go extinct?

Scientists are working on a trial mission to deflect an asteroid. The threats artificial intelligence pose still aren’t being taken as seriously as experts would like, and the nuclear apocalypse has been rated more likely by The Bulletin of Atomic Scientists.

While the eventual extinction of humans is inevitable, to say that it will happen anytime soon seems alarmist and to claim it will be because of machines sounds laughable. But when a group of scientists, including physicist Stephen Hawking, write, “success in creating AI would be the biggest event in human history — unfortunately, it might also be the last,” people listen.

In 2006, Hawking posted a question on Yahoo: “How can the human race survive the next hundred years?”

He isn’t the only one concerned. In January 2015, thousands of academics and cultural figures signed the Future of Life Institute’s open letter calling for a ban on autonomous weapons in order to prevent an artificial-intelligence arms race.

It is also possible that AI accidentally destroys humankind. The Machine Intelligence Research Institute says it is unlikely AI would destroy us maliciously, as AI devices probably won’t be programmed with morals. It’s more likely they could destroy Earth by altering the environment. In their report, Reducing Long-Term Catastrophic Risks from Artificial Intelligence, the institute calls the idea of a robot uprising “the stuff of science fiction,” but says AI “could harvest all available solar, chemical, and nuclear energy” to achieve whatever goals they’ve been programmed with.

The environmental change wreaked by AI could be more profound if you believe in the ‘Grey Goo’ theory. This is the theory that if self replicating nanobots programmed to disassemble everything and reorganize those atoms into replicas of themselves are developed they could end up consuming all of Earth’s biomass. Humans, like everything else on the planet, would then be transformed into a sea of grey goo. The theory was coined by the nanotechnology engineer Eric Drexler in his 1986 book Engines of Creation.

What are the odds that humankind will go extinct in the next hundred years? It depends on whom you ask. The UK’s 2006 Stern Review on the Economics of Climate Change estimated there is a 9.5 percent chance, while the Future of Humanity Institute’s survey concluded a 19 percent probability. One of the highest predictions from an expert came from Martin Rees, a member on the Doomsday Clock’s board of sponsors and co-founder of the Centre for the Study of Existential Risk at Cambridge University. He argues that civilization has a 50-50 chance of making it through the 21st century.

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Homo sapiens (modern humans) have existed for 0.02 percent of the last billion years. (Author: LadyofHats  CC0 1.0 Public Domain)

To give some perspective, 99.9 percent of all species that ever existed on Earth are already extinct, and the median mammal species lasts for 2.2 million years. Homo sapiens (that’s us) have been around a mere 200,000 years. Based on this, it could be easy to conclude we have another 2 million years left. However, that would be misleading because human threats such as nuclear warheads have only been around for the last 70 years and the previous statistic is only based on extinctions from natural events like climate change, asteroids and volcanic eruptions. Nick Bostrom, the founding director of the Future of Humanity Institute, says in one his papers that the likelihood of human extinction because of these kinds of natural risk, “is extremely small on a time scale of a century.”


However, there is always the chance that an asteroid hits the Earth and causes a mass extinction, as it did 65 million years ago. The asteroid that killed the dinosaurs [apart from birds] was only ten kilometers wide. Nonetheless, the heat it generated surrounded the Earth and cooked everything that lived on the surface. Even the impact of an asteroid as small as one kilometer wide could cause enough smoke and dust to enter the atmosphere to block out sunlight for several months, starving most of humanity.


Luckily, we’re on the lookout for potential species-destroying asteroids. In 1998, NASA launched the Spaceguard survey. The survey aimed to enlist astronomers to identify 90 percent of the estimated 900 plus near-Earth objects bigger than 1 kilometer. The agency achieved this in 2010. Now they are trying to identify 90 percent of such objects larger than 140 metres by 2020, but NASA says it won’t meet this deadline. As of July 2017, NASA’s FAQ section says, “About 74 percent of NEOs larger than 460 feet still remain to be discovered.” Of the nearly 15,000 objects discovered so far, none are on course for Earth.

That’s good because if scientists were to find an asteroid bound for Earth, Joseph Nuth, a researcher for NASA, said in a Guardian interview, “there’s not a hell of a lot we can do about it at the moment.” There is the possibility of either deflecting an asteroid or blowing it up. However, in the same interview, Nuth said that a previous asteroid, which narrowly passed Earth in 2014, was only identified 22 months before it did so, which, “is less than half the time currently needed to get a craft capable of deflecting such an object into space.” That’s why he recommends NASA build a rocket and an observer spacecraft to keep in storage so that the time could be cut down from five to roughly two years.

However, there is hope that in the future, asteroids on course for Earth could be stopped. NASA’s Planetary Defense Coordination Office was created in January 2016 and tasked with identifying and preventing asteroids from hitting Earth.

Furthermore, NASA, the European Space Agency and the German Aerospace Center are hoping to do a joint trial run of changing an asteroid’s trajectory. The project involves the European Space Agency sending up a spacecraft called AIM (Asteroid Impact Mission), the Germans creating landing spacecraft and NASA sending up a rocket called DART (Double Asteroid Redirection Test).

According to their proposal, spacecraft AIM will be launched in 2020 and reach two asteroids in 2022 – a larger one called Didymos and a smaller one orbiting it called Didymoon. Once there AIM will take high resolution pictures of the two asteroids which it will then beam back to Earth to provide information for rocket DART. AIM will then release a lander and several miniature satellites. The lander will land on the smaller asteroid, Didymoon, and gather information on its structure and density, while the miniature satellites will gather more information and test inter-satellite links in deep space. Rocket DART will then crash into the centre of asteroid Didymoon and AIM will study the effect this has on its orbit of Didymos. The lander still on Didymoon will then repeat tests, measuring its structure and density so it can be compared. The idea is that destroying just a small part of Didymos with rocket DART will change Didymos’s trajectory and in the event that a NEO object is on course with Earth, the same can be done.


Nuclear threats

Now let’s move on to the man-made threat most likely to cause human extinction: nuclear weapons. Bill Perry, a former Secretary of Defense for President Bill Clinton, said his biggest worry is that a terrorist group will acquire uranium. He explains with just 40 kilograms of uranium, terrorists could create an improvised nuclear weapon. In the VICE documentary, What Nuclear War Would Look Like, he says, “I think of all of the nuclear catastrophes that could happen, this is the most probable. I would say, there’s probably an even chance, this would happen sometime in the next 10 years.”

Humanity has come very close to nuclear warfare before, but not from terrorists. During the 1962 Cuban missile crisis, Soviet Union leader Nikita Khrushchev agreed with Fidel Castro to place nuclear missiles in Cuba to deter future invasions from America. In response, Americans established a military blockade to prevent further missiles from reaching Cuba, and there was a tense standoff for almost two weeks between the United States and the Soviet Union before Cuba agreed to disassemble their nuclear weapons in exchange for America doing the same with theirs in Italy and Turkey.

In the VICE documentary, Perry continues, “an all-out general nuclear war between the United States and Russia would mean no less than the end of civilization. That’s not being dramatic; that’s not being hyperbolic. That’s just what would happen.”

It could have happened again on September 26, 1983. An error in the USSR detection system reported that five nuclear missiles were on track for Russian targets. Luckily, the designer of the warning system who was monitoring it that night decided that an actual attack would involve hundreds of missiles, so the computer must be malfunctioning. Therefore he didn’t order a retaliatory attack.

However, one study found even if a more limited nuclear attack between India and Pakistan occurred (both countries have nuclear weapons and a fraught history) two billion people globally would be threatened by induced famine. This is because if enough nuclear firepower was used it could create a ‘nuclear winter.’

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The mushroom cloud after a nuclear bomb was dropped on Nagasaki on August 9th, 1945 (Author: Charles Levy Public domain)

The executive director of the Global Catastrophic Risk Institute, Seth Baum, refers to a ‘nuclear winter’ in his paper as nuclear warfare causing a cooling of the Earth’s surface so that winter-like temperatures occur during the summer. This might not sound that drastic but if a nuclear explosion was big enough, then enough smoke could enter the atmosphere that it blocks the sunlight from reaching the Earth and reduces rainfall, as well as temperature, which decreases crop production.

Seth Baum proposes a maximum of 50 nuclear weapons worldwide to avoid a “severe nuclear winter catastrophe” and says as few as 100 nuclear weapons would have “catastrophic global consequences.” Globally there are about 15,000 nuclear warheads. The U.S. and Russia each have about 7,000 and the rest are divided up among the remaining 7 nuclear nations.

Perhaps humanity is destined to end by nuclear warfare. After all, if the chances of intelligent life in the universe are so high so why haven’t we come across it? One theory is the Fermi paradox. This is the theory that either the chances of intelligent life appearing are very low or that before civilizations get advanced enough to explore distances light years away that they destroy themselves.

If you want to find out the effects of a nuclear bomb check out Alex Wellerstein’s NUKEMAP. It lets you see how many fatalities there would be depending on the location, power and other factors of a nuclear bomb explosion.

Doomsday Clock

The Bulletin of Atomic Scientists created a metaphorical clock in 1947 which represents how close humanity is to the threat of global nuclear war. The closer the clock is to midnight, the closer we are to a global catastrophe. In the 70 years the clock has existed, the safest the Bulletin has ever deemed us was 17 minutes to midnight in 1991. The closest the clock has been to midnight was in 1953 and since January 2018 when it has been two minutes away.

The Bulletin of Atomic Scientists was founded in 1945 by scientists who had worked on the Manhattan Project (the atomic bombs developed in World War II used on Hiroshima and Nagasaki). They started producing a newsletter, and then a magazine (now digital) called the Bulletin of the Atomic Scientists aiming to educate the public and politicians about the dangers of nuclear weapons.

The bulletin has always argued for the multilateral disarmament of nuclear weapons. Executive Director and Publisher of the Bulletin of Atomic Scientists Rachel Bronson told WikiTribune, “we’re strong supporters of the Non-Proliferation Treaty” and our main goal is, “to help manage the advancement of science and technology so that we really can reap its benefits, and we can be protected against its risks.”

The Bulletins’ Science and Security Board (currently 17 members) maintains the time of the Doomsday Clock in cooperation with the Board of Sponsors (currently 38 members). At present, the board has 16 Nobel Prize winners. Since 2007, the clock has also included the threat of climate change. They meet twice a year to review the situation, and then if they feel the risk of a global nuclear war or climate change has changed the clock is adjusted in January, with an accompanying statement.

Although there is no physical clock, the bulletin is running an exhibition on its history at the Museum of Science and Industry in Chicago, which runs through early 2018.

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