This is a DRAFT for a new blog post for my Science20 blog http://science20.com/robertinventor - sharing it here as this blog has few views, to work on it and discuss it with friends etc.
This is one of the questions I get asked most often since I started to cover the topic of asteroid impacts. Will humans will become extinct within a decade, or within a century? And can this happen through natural disasters?
Some people get very worried about this, and they are most worried, usually, about asteroid impacts. I blame the movies there. But what's the real situation? I'll focus on things that could happen in the next ten or twenty years, because technology advances so rapidly that it's hard to look much further ahead, as you can see from predictions of the present from, say, thirty years ago.
And this is about whether we can go extinct, not about things like famine or war. Even an all out nuclear war with a nuclear winter would not make the tropics as hard to live in as the Arctic - so some humans would still survive. Would anything else? What about climate change, or asteroid impacts?
Well, first, we are an extremely adaptable species, able to survive anywhere from the Kalahari desert to the Arctic, with only stone age technology. We had already colonized most of the world by the end of the neolithic period.
Overview of Pre-modern human migration - there is debate and controversy about the details, but generally agreed that humans were already present world-wide by the end of the neolithic period(which ends around 2000 BC) or shortly after.
So, as long as we retain at least stone age technology, there isn't much that could make us extinct.
Homo Sapiens is listed in the IUCN Red list of threatened speces - as one of the species of least concern
"Listed as Least Concern as the species is very widely distributed, adaptable, currently increasing, and there are no major threats resulting in an overall population decline."
The species is at least 100,000 years old. In that time, there have been volcanoes, earthquakes, tsunamis, floods - but no massive asteroid impacts.
But could anything make us extinct?
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GIANT METEORITE IMPACTS
Not a massive meteorite strike. Everyone says this, but if you look into the topic closely, it's not possible. We haven't been hit by anything this big for over three billion years. The big craters on the Moon, Mars and its moons, Mercury, a very old and huge eroded crater on Earth also - they all date back to over three billion years. Back then the solar system was still settling down into its current state - towards the end of the "late heavy bombardment".
The reason is that Jupiter protects us, so the simulations suggest. It breaks up really big comets, or they hit Jupiter or the sun or get ejected from the solar system before they get into orbits close enough to ours to be any problem.
They'll say - look at the meteorite strike that ended the dinosaur era!
But we are not dinosaurs. Turtles, crocodiles, alligators, small mammals, flying dinosaurs (the birds), dawn redwood trees, pine trees, many lifeforms survived that impact. And humans with the barest minimum of our technology are able to survive anywhere from the Arctic to the hotttest of deserts, or in tropical rainforests. We would survive, some of us, a giant impact like that.
And it is also extremely unlikely that we are hit by anything even that big. We have found all the 10 km diameter asteroids between Jupiter and the Sun already. Found 90% of the 1 km ones also. The 10 km ones happen only every 100 million years. And most of those are found leaving only ones that are currently way beyond Jupiter which also means we'd get a bit of warning at least.
So - that's both extremely unlikely - only 1 in 100 million in the next decade, perhaps less. And also would not make us extinct.
SUPERNOVA, GAMMA RAY BURST ETC
A supernova also would not make us extinct. None near enough to be deadly to earth anyway. But we are also protected by our atmosphere, and there would be many people on the other side of the world at the time. Same also applies to a gamma ray burst. And both very unlikely. The galaxy is a hundred thousand light years in diameter - so the next supernova is almost certain to be far too far away to harm us - and gamma ray bursts are very focused. and would need to be pointed directly at us - which again is very unlikely.
And - probably would be at least a fair few people in submarines, very hard to think of any disaster that could kill everyone in submarines. Tsunami are a surface phenomenon and a hundred meters or so below the surface you wouldn't even know it is happening chances are.
BLACK HOLES, ETC
As for black holes, well there can't be many mini black holes in the universe or we'd see stars blinking out. No large ones near to the sun, as we'd spot them by the accretion disk.
And not likely to create one ourselves, because the galaxy has natural particle accelerators the size of stars and larger - the fast particles they create which hit Earth regularly don't make mini black holes, or if they do, they are harmless - and we are nowhere close to duplicating those energy levels. We'd need to be able to build something like CERN larger than a star before it's a concern.
OUR UNIVERSE DYING
Nobody knows, it's all speculation. Even laws of physics might change on those vast timescales.
But one thing is for sure, it is very young so far. The galaxies are giving birth to lots of stars, which only young galaxies can do. As they get older they merge with each other and have less baby stars than before. And though some galaxies have already gone through to that stage, there are many very young spiral galaxies like our one.
They go through to the next stage by collision - when two galaxies collide together then they have a big rush of star birth, then nearly all the gas is used up as stars and it is over. Still have new stars from time to time, but only a few - and that's the old age of a galaxy. if that doesn't happen, then they will produce stars less and less often and the older stars gradually die and turn into white dwarfs, or black holes, or neutron stars. But who knows, maybe new lifeforms will arise then that find neutron stars, white dwarfs etc just fine as places to live?
And for trillions of years into the future there will be plenty of Earth like planets being born. Nobody knows quite what happens longer term than that.
SUPER VOLCANOES, SOLAR STORMS ETC
A super volcano would plunge us into a period of darkness and cold for many years. It's similar to a nuclear winter. But again, this would not make a species as adaptable as Homo Sapiens with at least stone age level tools extinct.
A solar storm from some types of star would be totally devastating. But ours is a quiet G type star in the middle of its life. It can't unleash a solar flare large enough to make us extinct.
The main risk here is for our power lines and any other long distance conducting cables. The great solar storm of 1859 happened at a time when the only long distant cables were telegraph cables. It caused sparks to fly in some cases giving them electric shocks. With our modern technology it could cause multi million dollar electrical transformers to fail - and more importantly - those would be hard to replace, and if so, power might be down for weeks or months. So the main question there is whether our power grid is sufficiently robust enough to withstand such an event. It would not make huamns extinct.
Tsunami obviously only affect coastal regions and low lying places.
Earthquakes are local in their effect and can't possibly make us extinct. Actually, they are much more limited in their effect than movie fiction suggests. It's just not possible for an earthquake to make California fall into the sea or even for it to swallow people up into cracks in the ground. See a geologist's critique of the movie 10.5.
As for clusters of earthquakes - well they can't set each other off, they are too far apart. This is just natural random clustering.
See List of earthquakes in 2015
If you look a the table, then there were 143 earthquakes magnitude six upwards. So it must be quite common for two to happen in a day. There are only 20 magnitude 7 upwards. Still there's a strange mathematical result - if you have a party with 23 people in a room, though the chance that you share a birthday with one of the others is only 22/360, the chance that any two of them share a birthday with each other, when you take account of all possible pairings, is 50%. See Birthday problem.
So at 20 or so a year, it must also be quite common that you get two of the magnitude 7 and upwards earthquakes in a day too.
Earthquakes often cause other aftershocks as they send tremors through the earth that can cause other faults to slip - and occasionally they can be as large as the original earthquake. So earthquakes could cause each other - but probably only over ranges of hundreds of miles, not so likely over thousands of miles. See this story from 2012: Are 4 Big Earthquakes in 2 Days Connected?
Earthquake Facts&Earthquake Fantasy
SO SAFE FROM EXTINCTION FROM NATURAL DISASTERS
So - natural disasters, it seems, can't do it at all. We are safe from extinction at least, not just for a century, but for thousands, even millions of years. Hundreds of millions of years into the future, then yes, we could go extinct through disasters of one type or another. Eventually the sun will get too hot - though - we could postpone that by using shades, or maybe even by moving the Earth itself further out. See Let's Lift the Earth.
There's a tiny chance of Mercury getting deflected from its orbit. There may be other things that could threaten us on a hundreds of millions years timescale.
But - it is very unlikely that the human species lasts that long. Some genera do survive for hundreds of millions years - rare for a species to though. Even horseshoe crabs have changed in their detailed structure over hundreds of millions of years. And hominid species typically last for only a few million years before the next one - no reason really to suppose we are different.
If somehow we continue as a species for hundreds of millions of years, then I think you can assume we have high technology that stabilizes our genome and probably if humans have survived for that long, as a high technology species, there isn't that much you need to be concerned about as regards natural events making them extinct.
DISEASES
That leaves, diseases. But you generally get a few immune to it if it is a natural disease.
It would be possible surely to genetically engineer some bug to intentionally make us extinct- but a few people would be immune, and there would also be others that never are contacted. If nothing else, then the uncontacted tribes, which still exist in a few islands and forests, would emerge from their forests bewildered to an uninhabited world :), That would make a fun sci fi story though I don't think it is likely in reality.
CLIMATE CHANGE
Climate change won't do this. It's effects are much exaggerated by a few people who go over the top, opposite to the climate skeptics, climate excessers ??
See for instance, How Guy McPherson gets it wrong
You also hear that we can turn Earth into Venus through climate change. This just can't happen. We would need to release and burn many times the entire global inventory of coal, oil, methane etc. We couldn't do it even if we never took any precautions.
Our world is technically in the middle of an ice age, compared with most of the Earth's history, because we have ice at both poles. That's because we happen to have a continent at the South pole and an almost enclosed ocean at the North pole, both of which help to cool down the Earth. Normally there is no permanent ice anywhere except on mountain tops and the world is much warmer than it is now.
So the main issue is not the temperature of the world, but the speed of the change. So, the world isn't going to become uninhabitable or suffer any kind of apocalyptic event as a result of climate change.
And - Earth gets plenty of energy from sunlight. Just a small area of the desert set aside for solar power collection could supply all our energy and be an end to the problem completely. But that's too expensive with present day technology. As time goes on and the technology improves, then it may well be we can do that; get all our energy from solar. There are other options also. It's definitely doable, lots we can do about it.
THINGS WE CAN DO TO OURSELVES
That leaves things we can do to ourselves.
ARTIFICIAL INTELLIGENCE
The idea of an AI intelligence taking over the world, well I don't find that plausible at all. Here I'm voicing my personal view and opinion.
I think we are a long way away from that, indeed that we will never build computers that can understand truth in the way a human can do. Indeed if we do have strong AI, I don't think it will be through programming, but rather through genetics, biology, or some such. Or some approach that is somehow part biology, part machine. Which would involve many ethical issues. E.g. enhancing the intellectual capacity of a whale and giving it the ability to speak like a human - is that an acceptable thing to do? What kind of life would such a creature live - would itnot potentially be very unhappy and miserable? Anyway we aren't close to that capability yet AFAIK.
Why Strong Artificial Intelligences Need Protection From Us - Not Us From Them
I can't see this happening within ten or twenty years for ethical reasons. In the long term, yes maybe. Could we genetically engineer our own future replacements? It's a while away yet though. And I expect if it happens at all, that it will be through genetics or something similar, artificial life, or could be half computer half living - but not through computing alone.
BLACK HOLES (AGAIN)
Some people worried that the experiments with the LHC at CERN would create a black hole that would destroy the Earth.
So first, most people don't think it will create a black hole. It is just some very unusual physics that would let that happen.
The idea is that if you hit two things together with enough energy - then by Einstein's E = mc^2, then that energy is equivalent to mass. With a fast enough collision, it could create enough mass in a small enough space to create a tiny tiny black hole, smaller than an atom.
The amount of energy when such tiny particles collide, even at close to the speed of light, is the same as the energy in two mosquitos bumping into each other. So you can't create anything very big. And what everyone expects from modern physics is that a mini black hole that small would just form briefly and instantly fall apart, through Hawking radiation or other processes.
But in assessing safety they had to acknowledge that this is not absolutely proven, of course, is always possible that some new physics we don't know about comes into play.
To answer that, they looked at mini black holes that would be created by cosmic rays hitting neutron stars and white dwarfs - very dense stars. These stars could trap even neutral mini black holes with no charge - so if there were any black holes created in a process like that and they were stable and able to swallow up the Eaerth they'd be created in huge numbers by cosmic radiation hitting white dwarfs and neutron stars and those very dense stars then wouldn't be able to survive.
Yet they do, because we can see them, very ancient and very dense stars. So even if we are completely wrong about Hawking radiation, and mini black holes are stable - then the continuing existence of these very dense stars shows they can't be dangerous to the Earth.
NANOTECHNOLOGY
As for nanotechnology - we could make tiny nanomachines, already do. But we are nowhere near able to make a nanite - a nano replicating machine. Nowhere near.
We can't even build a "clanking replicator" - a factory or solar panel or some other big machine or device able to create a copy of itself. The advances in 3D printing take us partly there, but still need humans to source the materials they use, and to build the copy of the printer, as well as not being quite at the stage of printing out computer chips.
That could happen, nanoreplicators, see no reason technically why not. But surely not in just ten years. Don't think that is long enough to get to a "clanking replicator" many steps to be filled in though there are ideas about how we could do it.
So again this is for further into the future, can't see us getting there in ten or twenty years. By the time it is possible, then we may well also have the means to control it too. I think it is just too far ahead to concern ourselves with in any detail.
EXPERIMENTS WITH LIFE
The one thing that I do think needs great care is life itself. Experiments like this one:
Synthetic bug given 'fewest genes' - BBC News
And particularly
That's DNA with six bases instead of four.
The researchers take great care, and I'm sure will continue to do so.
DNA IS OPTIMAL BUT - ONLY A LOCAL OPTIMUM
The thing is we don't know that DNA based life is optimal. We have only the one example, and there is no way that life could have explored the entire solution space when DNA evolved. It could easily be a "local maximum" that seems optimal because evolution had a bit of a blind spot and never explored some particular direction. This can definitely happen with higher animals, e.g. Australian marsupials never evolved into mammals Could that have happened with microbes also, that Earth life has never evolved some more optimal form of life that we could either make in a laboratory or find on another planet?
As an example of how non DNA based life could be better than DNA life - it could require smaller cells (DNA life though it works is Rube Goldberg in its complexity and life that can work with less complexity could be much smaller) meaning it needs less resources and can reproduce more quickly. It could have a more efficient faster metabolism. It could have a biochemistry that is in some way more robust to environmental hazards. It could be better at photosynthesis - just a few percent improvement, if DNA life can't match it, could mean that it takes over through an exponential process, from green algae in the sea, basis of much of the marine food chain.
It could produce chemicals poisonous to us as a byproduct - like BMAA which is possibly implicated in Alzheimers misincorporated in place of l-serine which it resembles quite closely. There's no advantage to green algae to cause Alzheimers in humans and in the same way there need be no advantage to the XNA life to create chemicals poisonous to humans or other Earth life, it might just be that that's how it works. It could well be invisible to Earth life, not perceived as a threat because it doesn't produce any of the carbohydrates and peptides that our and cells defences respond to. So they don't respond to anything except the actual physical trauma. It might just live for instance in our stomachs, linings of our lungs, mouths, on our skin, and our body does nothing to stop it, and then harm us either by eating us directly, or by chemicals it produces. It doesn't need to harm humans to be a hazard. If it harms any of the lifeforms we depend on, it could be just as problematical, and either lead to our extinction or severely diminish the habitability of the Earth for humans.
Exponential growth would start slowly, but then continue more and more rapidly - and it is surely low probability in the first place, Bevertheless, it could potentially in theory happen in a decade. E.g. that some form of life is created that can survive on and in humans as well as other animals that our immune system doesn't recognize and produces chemicals harmful to us. One of the applications of artificial life is the possibility of using it to make implants that our bodies won't reject, so that's a line of research that if the researchers were careless could lead directly to a lifeform that could be harmful to humans and hard to protect against. Again not saying we shouldn't follow this research, just saying it needs care and if it was done very carelessly it could have the effect described.
For that reason also, as well as others, I think we need to take great care returning samples from another planet that may have life in them. It's not likely that we can return a sample from Mars before 2025, because it would take at least a decade just to pass all the laws needed to permit such a sample return, and that process is not started yet.
So - though a low probability, I think that's one of the few things that could make us extinct. Also genetic engineering. Both could be really good positive things, so I'm not saying we must never do these things. But they need a great deal of care. Humans have never been able to do such things, and past experience of doing other things may not be a reliable guide.
Tiny probability. But when existential risks are concerned, we have to consider tiny probabilities.
The good news is that these are things we can do something about by making sure we take care.
OTHER RISKS
There are other possible risks. You could start with Nick Bostrom's list. Existential Risks
But it is a bit out of date. For instance he mentions runaway global warming, which is now known not to be possible through just burning fossil fuels etc. Perhaps he wrote this at a time when a scientist had just published research that for a year or two seemed to show that it was possible.
've already argued that asteroid impacts can't make us extinct.
It gives an idea of some of the things that some people have thought needs to be looked into. The ones I mention here are the ones that seem closest to possible. His list is not just of human extinction events but things that could permanently reduce life prospects.
Also, it is based on ideas of post humanism, such as that in future mind uploading would be possible, on the idea of super intelligent programs etc. If you don't think any of those are possible, as I don't, then many of the things in the list are things you don't think could happen. If you think those are possible, well his list will suggest other future possibilities.
Some of the transhumanists think we could achieve some kind of a runaway technological event they call the "singularity" which would happen in the near future - that depends on this idea of super intelligent computer programs. If you are a believer in this, then you'd think we could become extinct as a result of a badly programmed superintelligence taking over the world.
For me that's just science fiction, as explained in Why Strong Artificial Intelligences Need Protection From Us - Not Us From Them and a couple of other articles linked to from that one.
WACKY WAY OUT IDEAS FOR HUMAN EXTINCTION
You might be amazed how many of these way out ideas there are for extinction that some get worried about.
Here are some of the ones that got a fair number of people worried last year.
- Pole shift - from time to time the magnetic poles swap over so that North becomes South and vice versa. But this is a change in our Earth's magnetic field, not its spin axis, and only makes a difference to the direction our compasses point and might confuse migrating birds.
The magnetic poles move independently of each other and are currently both close to the respective geographical poles. Before a pole shift, they would migrate down to the equator. Like this:
This shows the motion of the Earth's North magnetic pole - as you can see it is moving quite rapidly at present. But it is close to the North pole.
And this is the motion of the South magnetic pole
They move independently of each other, because the Earth is not a bar magnet but a more complicated type of magnet, with the field created by movements of electrical currents deep underground. The blue lines there show the motion of the geomagnetic poles - the poles of an idealized bar magnet approximating the Earth's magnetic field as closely as possible - useful for theoretical analysis but not real, your compass won't point that way.
If we did have a magnetic pole shift, the main effect would be less protection from solar storms. So more solar storms, which I've already covered. Then the Ozone layer would be reduced, so you'd need protection from UV light. People do this anyway if they spend a lot of time out of doors in very sunny conditions, indeed doctors recommend that anyone who does sunbathing or spends a lot of time out of doors protects against UV-B in this way.
Protect your skin and eyes in the sun
We would also lose more air from the upper atmosphere than usual - but this is not a significant effect - bear in mind that we have had many magnetic reversals. They are over quickly on geological timescales, and do not have any noticeable effect on the Earth's atmosphere.
Earth has had many pole reversals. The most recent one, which lasted 440 years was only 41,000 years ago. Laschamp event Reversals can happen quickly within a human lifetime. But they are not enormously hazardous. Don't even cause extinctions. See also my What will happen when the magnetic poles shift?
The magnetic field would get weak during a pole shift. The magnetic field strength is dropping, but recently researchers have found out that it was anomalously high, so it is dropping back towards its average value So, it doesn't seem that a pole shift is imminent.
Our planet also does a slow predictable wobble of its axis - rather like a precessing top - that takes thousands of years.
This changes the direction of the North pole over a 25,700 year cycle. See Polar Shift and Equinoxes drift.
The reason the Earth's axial tilt doesn't change is due to the stabilizing influence of our Moon. Mars' axis changes its tilt from almost vertical to so tilted that it has equatorial ice sheets. See Changes of tilt of the Mars axis
And then you get true polar wander, where the planet's axis itself moves - but this happens due to processes such as large volcanic eruptions and continental drift over time periods of millions of years. And it only shifts slightly.
Pole shifts are not an issue at present.
- Hit by a previously undiscovered planet such as Nibiru - I mention this because many astronomers say it is the number one question they get asked - are we all going to be killed by the planet Nibiru? Please see my Simple Ways To See Nibiru Is Totally Nuts - And Limits On Planets Hiding In Our Solar System
- Big rip. This is a genuine theory in cosmology - though just one of many ideas about how our universe could end. It predicts that the universe could tear apart - but - this is 22 billion years in the future. Our sun has only been here for 4.7 billion years, and has had complex multicellular life for only 0.5 billion years. Most cosmologists think the universe will last for trillions of years, so compared with that, this is a near future scenario. Still, not something that most people will be concerned with except cosmologists.
- Result of a prophecy. People have been prophecying that the world will end suddenly, for many centuries. Recently you get prophecies like this every few months. These "prophets" may give lists of their previous "successful prophecies". This may seem impressive if you look only at their successes in the list.
But people who fancy themselves as prophets will make dozens of prophecies, and if only a few of them come true they then think they have some magical view into the future.
Also bear in mind that there are many people trying to prophecy the future every year, and only the ones that happen to make a successful prophecy ever hit the news.
And the ones who happen to "get it right" once, understandably get impressed by what happenend, and tend to think they are onto some truth and then go on to prophecy other things. The dutchman who "successfully" prophecied a major earthquake last year within two days of the Nepal quakes for instance hit the news when he went on to prophecy a big earthquake in California which of course didn't happen.
Last year we had many people prophecying that there would be an apocalypse at the time of the "blood moon" which is a recently coined word for the fourth in a series of lunar eclipses. The Moon goes red as a result of the combined sunrises and sunsets throughout the world. There is nothing there of any harm to humans. But it got people very worked up because of people who claimed to prophecy apocalyptic events at that time. See my September 24th, 2015 - Just Another Day In Space - Asteroid Flybys, "Blood Moons" And Armageddon Demystified
If only it was that easy to do astronomy - to just look into your "crystal ball" and predict, say, that a particular star has an exoplanet, or predict the next comet or supernova, or predict what Curiosity will find next on Mars, or predict the Chelyabinsk meteorite, etc etc.
So far prophecy has not turned out to be helpful at predicting things in astronomy or geology or other natural events.
- Proofs by correlations - if someone says that e.g. Eclipses cause earthquakes, and shows a table that seems to link together, then that's an attempt at "proof by correlation". Anyone with a good scientific background knows that there are many pitfalls in arguments like that, which you need to use careful methods and reasoning to guard against. 15 Insane Things That Correlate With Each Other .True Fact: The Lack of Pirates Is Causing Global Warming
Here is an article I wrote about: How To Keep Earth Safe - Samples From Mars Sterilized Or Returned To Above Geostationary Orbit - Op Ed
And about asteroid impacts Giant Asteroid Headed Your Way? - How We Can Detect And Deflect Them
You might also be interested in my answer to Is it true that a neutron star will hit the Earth in 75 years from now? The answer is No, vastly improbable, but is fun to look at.
ANY OTHER RISKS?
Is there anything else that you have heard might make us extinct? Do mention it in the comments section, and I'll see what I can find out about it. Thanks!
As usual also, do say if you spot any mistakes here, however small, whether typos or something more substantial.
