Astronomy Awareness Science X-Files

World’s End: 10 Things That Could Actually Destroy Life On Earth


“The ashes of your existence will fertilize the soil for the universe to follow.” 
― Richard Kadrey, Sandman Slim

Doomsday is big concern for astronomers and a favorite with fiction writers and film-makers  alike. After all, the human race has been here for the best part of 2.8million years. But all good things must come to an end and, sooner or later, so must humanity’s stint on planet Earth.

There are so many other ways in which the human race could be wiped out any day now: from catastrophic climate change to black holes and robot wars – here are 10 apocalyptic visions that could end the world as we know it.

1 – A giant asteroid impact

World's End: 10 Things That Could Actually Destroy Life On EarthCourtesy of (Image Source)

Responding to challenges to the hypothesis that an asteroid impact caused a mass extinction on Earth 65 million years ago, a panel of 41 scientists re-analyzed data and provided new evidence, concluding that an impact in Mexico was indeed the cause of the mass extinction . This asteroid was about 10 to 12 km in diameter, which is large, but less than 0.2% the diameter of the Earth. It’s pretty unremarkable, and makes it a pretty typical minor asteroid. For comparison, this makes it about half the size of the known asteroid Gaspra. The thing that makes this asteroid so vicious, though, is that it had so much kinetic energy when it hit the planet! The great trick here is realizing that the asteroid gets pulled in by the Sun, and that — by the law of conservation of energy. NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes.

For a real chill,  Kuiper belt, a zone near Neptune, contains roughly 100,000 asteroids > 50 miles in diameter. The Kuiper belt sends a steady rain of small comets earthward. Impacts might occur over the ocean, and small over land might affect unpopulated areas. But with big asteroids, it doesn’t matter much where they land. Objects more than a half-mile wide- which strike Earth every 250,000 years or so- would touch off firestorms followed by global cooling from dust kicked up by the impact or they would simply end in breaking the earth into pieces.

2 – The Earth could pass too close to a wandering black hole

World's End: 10 Things That Could Actually Destroy Life On EarthInfrared Echoes of a Black Hole Eating a Star Photo © NASA

Our galaxy is full of black holes, formed when giant stars collapse in on themselves. Their gravity is so strong they swallow everything, even the light that might give away their presence.

In July, scientists from Durham University discovered five previously unidentified “supermassive” black holes billions of times the size of our sun, increasing fears one could come closer to earth than previously anticipated. Such a black hole wouldn’t need to swallow us up. Just passing nearby could hurl the Earth out of the solar system into deep space.

New study suggests however that black holes are doors to other parts of the universe. But you wouldn’t ever get to come back.

Anyone who managed to get through one of the mysterious doors would end up “spaghettified”, and stretched out like a long strand of pasta, according to the research. They’d get squished back down to size once they reached the other side, but it’s unlikely they’d be alive to see it.

Previously, scientists have held that all matter inside of a black hole is destroyed and so there would be no way of ever actually making it through. But the new research suggests that it could act as a doorway or a tunnel – as in a sci-fi story.

3 – Global warming

World's End: 10 Things That Could Actually Destroy Life On EarthNASA predictions of global warming effects in 2099

By the end of the century, the global temperature is likely to rise more than 2 degrees Celsius, or 3.6 degrees Fahrenheit.

This rise in temperature is the ominous conclusion reached by two different studies using entirely different methods published in the journal Nature Climate Change.
One study used statistical analysis to show that there is a 95% chance that Earth will warm more than 2 degrees at century’s end, and a 1% chance that it’s below 1.5 C.
The second study analyzed past emissions of greenhouse gases and the burning of fossil fuels to show that even if humans suddenly stopped burning fossil fuels now, Earth will continue to heat up about two more degrees by 2100. It also concluded that if emissions continue for 15 more years, which is more likely than a sudden stop, Earth’s global temperature could rise as much as 3 degrees.

Why two degrees?

The 2 degree mark – that’s a rise of 3.6 degrees Fahrenheit in global temperature – was set by the 2016 Paris Agreement. It was first proposed as a threshold by Yale economist William Nordhaus in 1977. The climate has been warming since the burning of fossil fuels began in the late 1800s during the Industrial Revolution, researchers say.
If we surpass that mark, it has been estimated by scientists that life on our planet will change as we know it. Rising seas, mass extinctions, super droughts, increased wildfires, intense hurricanes, decreased crops and fresh water and the melting of the Arctic are expected.
The impact on human health would be profound. Rising temperatures and shifts in weather would lead to reduced air quality, food and water contamination, more infections carried by mosquitoes and ticks and stress on mental health, according to a recent report from the Medical Society Consortium on Climate and Health.
Currently, the World Health Organization estimates that 12.6 million people die globally due to pollution, extreme weather and climate-related disease. Climate change between 2030 and 2050 is expected to cause 250,000 additional global deaths, according to the WHO.

4 – Magnetic reversal

World's End: 10 Things That Could Actually Destroy Life On EarthEarth's Magnetic Field | by NASA Goddard Photo and Video

Every few hundred thousand years the planet’s mag­netic field dwindles away then, over the next century, reappears with north and south poles flipped.

We know of about 170 pole reversals over the last 100million years. The last was 781,000 years ago, which makes the next one well overdue. European Space Agency research shows the magnetic field is weakening 10 times faster than previously thought and it might flip within the next 100 years.

Does it matter? Well, the magnetic field deflects particle storms, cosmic rays and even more powerful particles from deep space. Scientists say without it our ozone layer would be stripped, with disastrous consequences for life.

 5 – Gamma-ray Bursts

Flashes of gamma-ray light are thought to be caused by the merging of two collapsed stars. They are the most powerful explosions in the universe with up to 10-quadrillion times the energy of our sun.

Current estimates are that a gamma-ray burst will happen in our galaxy, or in a nearby galaxy, about once every five million years. However, it’s pretty likely that the radiation would not have an impact on Earth. It has to happen pretty close to us for it to have an effect.

World's End: 10 Things That Could Actually Destroy Life On EarthA computer animation of a gamma-ray burst destroying a star.

It all depends on the beaming. Even objects very close to a gamma-ray burst can be unaffected if they’re not in the beam path. However, if an object is in the path, the results can be devastating.

There is evidence that suggests that a somewhat nearby GRB could have occurred about 450 million years ago, which could have led to a mass extinction.

But the evidence for this is still sketchy.

A gamma-ray burst, beamed directly at Earth is pretty unlikely. However, if one did, the amount of damage would depend on how close the burst is. Let’s assume that one occurred in the Milky Way galaxy, but very far away from our solar system.

With the gamma-rays beamed directly at us, the radiation would destropy a significant portion of our atmosphere, specifically the ozone layer. The photons streaming from the burst would cause chemical reactions leading to photochemical smog. This would further deplete our protection from cosmic rays. Then there are the lethal doses of radiation that surface life would be experience. The end result would be mass extinctions of most species of life on our planet.

Luckily, the statistical probability of such an event is low. We seem to be in a region of the galaxy where supermassive stars are rare, and binary compact object systems aren’t dangerously close. Even if a GRB happened in our galaxy, the likelihood that it would be aimed right at us is even more unlikely.

So, while GRBs are some of the most powerful events in the universe, with the power to devastate life on any planets in its path, we are generally very safe.

6 – Devastating solar storm

World's End: 10 Things That Could Actually Destroy Life On EarthOn August 31, 2012 a long prominence/filament of solar material that had been hovering in the Sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. Seen here from the Solar Dynamics Observatory, the flare caused an aurora on Earth on September 3.

The sun is constantly “sneezing” powerful solar eruptions onto Earth, increasing the risk of cancer and causing power cuts.

Massive eruptions could bring about the destruction of electronic devices and increased cancer risk for aeroplane passengers Just one nasty storm could plunge entire cities into darkness by knocking out power grids and bringing down communications networks. Some scientists have suggested that solar flares caused Mars’ atmosphere to be worn down, leaving it the arid red planet we know now.

Could Earth end up looking like the barren Red Planet in the future?

7 – Nuclear war

World's End: 10 Things That Could Actually Destroy Life On EarthModern nuclear weapons are terrifyingly powerful.

Some fear that a nuclear war is more likely to happen now than at any other point of history since the end of the Cold War. Atomic tensions are running extremely high since North Korean dictator Kim Jong-un claimed he has the ability to hit New York with nuclear weapons. The tubby tyrant has spent years publishing pugnacious propaganda which shows bombs dropping on the Statue of Liberty.

President Donald Trump is now locked in a war of words with North Korea after it flexed its muscles in an unprovoked missile test that saw it fire a missile directly over Japan. If Trump follows up on the warning that he would retaliate with “fire and fury” if North Korea threatens US territories, we could be in a pretty hairy situation.

Modern nuclear weapons are terrifyingly powerful.  The largest bomb ever designed, the Russian Tsar Bomba, would wipe out everyone within 2 miles of the area and then leave a contaminated wasteland spreading five miles either way from the impact zone.

About 90 percent of the people in this disaster zone would die, with many suffering lingering deaths from radiation or extreme burns from the blast. If there is a nuclear war, there is little chance humanity would survive.

8 – Supervolcano

World's End: 10 Things That Could Actually Destroy Life On EarthAn early stage of the July 12, 2009 eruption of Sarychev volcano, seen from space

If a supervolcano was to explode it would send so much dust into the atmosphere that it would block out the sun. Right now, Campi Flegrei in Italy is considered one such super volcano, and there are currently concerns over whether it’s about to blow. Europe was devastated by an eruption some 39,000 years ago when the Campanian Ignimbrite volcano spread ash as far as 2,000km away.The vast amounts of sulphur dioxide released in this cataclysm is likely to have caused a volcanic winter that plunged huge amounts of Italy, the Mediterranean and eastern Europe into darkness and covered the soil with up to 20cm of ash.

A disaster of this kind might not instantly kill off the entire human population, but it could make food production very difficult and cause mass starvation across the world.

Animals would take in toxins and the ground would appear brighter, potentially reflecting solar radiation back into our atmosphere to cause a drought, the University of Oxford’s David Pyle told the BBC.

If there’s no water and no light, there’s no food. Humanity would find it very difficult to survive this sort of catastrophe.

9 – Pandemic

World's End: 10 Things That Could Actually Destroy Life On EarthBiological warfare is another threat that looms over the modern world

One of the most dangerous threats to the human population is a simple virus — that is, a deadly disease that spreads rapidly throughout the world. Within the last century we’ve had four major flu epidemics, as well as HIV and SARS, and scientists says it’s inevitable that another will occur. The 1918 influenza outbreak killed more people than World War I, and if a deadly contagion surfaced today, it could spread even faster and infect even more people. Considering how quickly diseases spread though all forms of modern transportation — and the amount of international travel that takes place today — an outbreak similar to that of 1918 “could have a more devastating impact,” says Maria Zambon, head of the Health Protection Agency’s Influenza Laboratory.

And if nature doesn’t send such a deadly contagion our way, mankind just might. Biological warfare is another threat that looms over the modern world, and diseases like anthrax, Ebola and cholera have all been weaponized.

10 – Artificial Intelligence

World's End: 10 Things That Could Actually Destroy Life On EarthRobots will have taken over most jobs within 30 years leaving humanity facing its 'biggest challenge ever' to find meaning in life

The Terminator films are still a sci-fi fantasy but robotic killing machines that act on their own are not too far from reality.

The UN have called for a ban on killer robots, presumably due to the fear that several countries are developing them.

Inventor Elon Musk, co-founder of Paypal, says artificial intelli­­gence might be the “greatest existential threat” humans face. Professor Stephen Hawking recently said: “The development of full artificial intelli­­gence could spell the end of the human race.”


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