Monday, December 04, 2017


I have come to the realization that someday, somehow, if humanity continues to exist, we will run out of something - something important.

I have, for a long time, thought that this thing would be energy as the universe slowly cools. However, I came to the realization recently that an eventual shortage of water seems far more likely.

For my Environmental Philosophy course, I have been studying, among other things, the mining of asteroids.

One of the value propositions concerning the mining of asteroids is the mining of water. It currently costs about $22,000 per liter to deliver water into space from earth. It may be possible to harvest water from an asteroid and deliver it to near-earth space at a much lower price.

Water makes one of the most valuable rocket propellants. You pass an electric current through water (using solar power to generate electricity) and split the water into oxygen and hydrogen. You separate them and cool them, and you have the liquid oxygen and liquid hydrogen that you can use to fuel rockets.

The rockets in question include not only probes - and perhaps colonization transport to Mars - but satellites. Communication satellites in geosynchronous orbit must burn fuel to hold their position. Small changes in the gravitational influences on a satellite serve to eventually pull it out of alignment, and a boost of an engine is needed to return it to position. There is also the fuel needed to get to the asteroid, mine the water, and return the water to earth orbit.

Water, when it is used as rocket fuel, (or anything used as rocket fuel, though other forms of navigation through space do exist) is a non-renewable resource. Whatever is lost out of the nozzle of a rocket is widely dissipated through the solar system, and may leave the solar system entirely.

I am not talking about some immediate short-term crisis whereby we must stop using rocket fuel immediately or we will run out by the end of the century. There are whole moons made substantially out of ice, as well as comets and asteroids. At the moment, this is not a practical concern. However, it is not at all difficult to imagine that we could burn through those resources in a lot less time than it will take for the sun to go dark.

Which invites the question, "How much time do we have?" and "What can we do to extend our life expectancy?"

We will eventually have to stop mining iron, nickel, and copper. Even asteroid mining merely postpones the inevitable. The thought that humanity (or whatever form of life we evolve into) may last far into the indefinite future may not be as likely as some of the more optimistic of us have wanted to believe.

And, ironically, it seems that the one thing that we can count on to last for billions of years, even though huge amounts of it is wasted every second, is energy. Energy is not a long-term problem, so long as the sun shines. Everything else, however, seems to be much more limited.


FredT said...

Carbon dioxide is rising and that will get us before we run out of anything. The Co2 rise is causing temperature rise, which is causing methane hydrate to melt, freeing methane, which drives more warming. We are at the point of no return without a massive dust cloud. Man has done this to ourselves, and we cannot stop.

Alonzo Fyfe said...

I haven't read any science that says that this could result in human extinction.

Most of the carbon that used to be in the atmosphere is trapped in limestone rock and ocean sediment. It gets locked into the shells of clams, oysters, and the like. Much of it has become sedimentary rock. Consequently, even if we use up all of the fossil fuels, we cannot put more carbon dioxide into the atmosphere than there was about 500 million years ago, when there was about 6000 ppmv (compared to the current 400+ ppmv).

The concept of "bad" is not limited to "human extinction", so the fact that we will likely avoid human extinction does not imply that things will not be bad.

FredT said...

The reason the atmosphere Co2 is rising is the rate of production is greater than the oceans can form carbonates. Some of that is acidification of the oceans is occurring, which reduces the rate of carbon fixation into various carbonates. We know that from the equilibrium of chemical reactions, first year chemistry, 47 years ago.

Extinction is not likely, more likely reduction in population, but seniors with breathing difficulties will be typical. The young will adapt to higher Co2 levels, and by the time they are old, the Co2 will be higher still, and they will have breathing difficulties. Oh well, in the end we all die anyway. Mass extinction, disease of some form, nuclear war... list goes on, who known what, may get humans or not; just evolution may be the end. We have changed the planet so much.

Also note that when the earth had 6000ppm, the only mammals were small. A lot of evolution has occurred since.

Doug S. said...

The worst case scenario for global warming is a replay of the Permian mass extinction. The hypothesized mechanism is that warming might disrupt ocean currents that mix oxygen-rich water from the surface and oxygen-poor water in the depths, leading to regions in the depths with less oxygen than normal. This leads to an overgrowth of anerobic bacteria that produce hydrogen sulphide, a poisonous gas that kills pretty much everything, including plants. Dying marine life will make the oxygen-free ocean regions bigger and bigger, until finally the hydrogen sulfide starts to reach the surface, gigantic amounts of poison gas bubble up out of the ocean, and the atmosphere becomes poisonous enough to kill off most multicellular life on Earth, including humans.

This is not a particularly likely scenario, but something like it is believed to have been a major cause of the Earth’s largest mass extinction, with massive volcanic activity having been the trigger. Human extinction is not completely out of the realm of possibility when it comes to consequences of extreme climate change.

Anonymous said...

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