15 April 2021

Escape to Space?

I wrote a version of this to a friend with whom I'd had a debate about whether humanity will have to save itself from coming catastrophes by literally escaping into space. This is an idea which I find preposterous on several levels, but I take it seriously and address it, in an admittedly somewhat disorganized fashion.


Let me try to lay out my reasons for why I'm so insistent that "escaping" from a "dying Earth" is a hopeless, but in any case implausible, scenario. Obviously, you're entitled to a different view, but I honestly think the case is so overwhelming that only insistence in the face of reasonable inference from facts can lead to any other conclusion. I don't have a "stake" in convincing you of anything, but I'm interested in these issues and think they are of vital importance to humanity's future, so I'm going to try to at least explain why I think the way I do. This is all rather off the cuff, but I've thought about it a fair amount and read quite a lot about the underlying facts, so I'm happy to go into whatever depth you think we can or should.


First, why I believe that even if the Earth were so compromised that human survival could be achieved only by transporting a large number of people to some other place, such an enterprise, at any time in the foreseeable future, is almost certainly doomed to failure. As an aside, you seem to be thinking some other planet, but I'm pretty sure if it came to this the attempt would have to be made to build a space habitat in near-to-earth solar orbit. Where materials from the moon and the rapidly deteriorating Earth could at least be used to jumpstart the project. The only plausible scenarios in which I see this playing out involve the collision of an enormous bolide that would literally wipe out life on Earth. Even a Permian level extinction event would probably be better addressed primarily on the surface of the planet, whereas a major solar system wide event, such as a sudden change in the sun's output or the approach of another star or black hole (or dark matter disruptor), would probably be curtains for us at any stage of technological development we're likely to achieve in the next several millennia at least, and technology could not save us. More about what kinds of catastrophes might occur and how we might deal with them later.


I'm sure you're familiar with the "Gaia" hypothesis, wherein life on Earth is interwoven in extremely complex reciprocal self-regulating systems that keep the atmosphere breathable, the ocean salinity within a livable range, the carbon cycle regulated so as to keep global temperatures and life-chemistry (nutrients) at livable levels, etc. There's nothing mystical about this, it's just that evolution works on many different levels, and the highest tier is planetary ecosystem. Natural selection tends to optimize aspects of even this system, because the optimizations succeed where the poorer adjusted systems fail. I mention all this because it has proven to be essentially impossible, with anything like present technology, to replicate these kinds of reciprocally self-regulating systems artificially on small scales. In other words, without a lot of energy and supplies from home, it is... so far... impossible to create a self-sustaining colony in space. Attempts to do this in controlled experiments failed miserably in a fairly short period of time. (Biosphere I and II).


OK, sure, eventually, it's undoubtedly possible, but even with all the resources of a thriving civilization, the creation of sustainable artificial habitats has proven to be beyond our capability. Incidentally, the example of something like the USS Enterprise (not that such exists), or an O'Neill space habitat, which seems like a feasible enterprise, are not counterexamples. Such habitats would be dependent on supplies, personnel, technology, assistance, and synergistics from and with the planetary civilization that created them. Sure, again, eventually, we will build things big enough and understand well enough how to ensure their independence and long term stability. But it appears quite clear to me that we are nowhere near this level of technological ability or understanding at present, and that if faced with the immediate necessity to construct a sustainable habitat with no input from Earth anytime in the foreseeable future, such efforts would almost certainly fail. Happy to talk about this in greater depth, but my conclusion is this: if our species has to abandon Earth at any time in the next few thousand years due to catastrophic failure of the habitability of our planet, we are simply doomed, full stop. We cannot possibly manage to replicate a planetary ecosystem in miniature without resources and supplies from a planetary civilization. In the bolide scenario I mentioned, we would surely try, but I think our chances of success are extremely bleak.


As far as reaching already existing planetary biospheres on exoplanets goes, there are myriad problems that make this completely nonviable in the foreseeable future. Not least of which is that, except possibly for tiny automated probes, we are nowhere near the capability of constructing interstellar vehicles that could transport large numbers of people. In any case, there is no reason to believe from what we know of exoplanets that there are any anywhere near the Sun that would be easier to adapt to and live on than artificial habitats, or planets or moons, in the Solar System. We have no evidence that any of them has an oxygen atmosphere, or conditions anywhere near similar to Earth, even if some of them could sustain, potentially, some form of life. Again, eventually, I feel sure humans will venture to the stars, but as a short term survival option, this prospect is completely off the table. Of that I am quite sure.


But this is really getting ahead of the main issue, as I see it. Which is this: apart from the bolide or solar system wide catastrophes mentioned, we are more likely to be able to survive an ecological catastrophe on our planet by adapting to it here, on the planet, rather than trying to escape from it. We may use space resources to deal with the crisis, whatever it may be, but the core of humanity that survives, if it does, will remain on Earth.


Let's consider some of the possible near term catastrophes that might happen, excluding a killer asteroid of the sun going nova. A less-killer asteroid, including even the Mesozoic/Paleogene extinction level event 66 million years ago, would actually probably be survivable. We would have very little warning of it, and not be able to transport any significant fraction of the population off the planet anyway. Surely it would be truly terrible; perhaps 90% of humanity would perish within a short time. But from what I understand of what happened then, we could harden our habitations in places not actually vaporized or destroyed, and probably manage to survive. Not in space, but on Earth.


A worse scenario would be something like the Permian Extinction, which is believed to have been cause by the wholesale poisoning of the atmosphere by massive traps of continental basalt, in what is now Siberia. (There may have been other factors as well). 99% of sea and land based species became extinct. But this kind of thing does not happen overnight; we would see it coming and could start preparing for it, figuring out how to mitigate the effects. Some effort to build space habitats would no doubt be involved, but the great mass of humanity would remain on Earth while our species tried to figure out how to live through such a crisis. Life, including advanced animal life, survived the original event, without the benefit of intelligence or technology, so my bet would be we would figure out how to survive too.


The most frequently considered catastrophe humanity is faced with, which we are already in the midst of, is of course the Climate Crisis. Human beings are, in fact, very busily engaged in innovation and technological transformation to deal with this crisis, and I am actually pretty optimistic that we will achieve zero carbon energy technology and transition to sustainable advanced energy infrastructures in the relatively near term (let's say 200 years). There may be some really nasty episodes in the interim, but from what I understand, the chances that this will just run away from us and we will actually face extinction are quite low. As an interesting precedent, consider the PETM (Paleocene/Eocene Thermal Maximum). This event occurred a little under 56 million years ago and lasted about 200,000 years. Probably caused by massive volcanism that raised the CO2 levels in the atmosphere far beyond anything seen since, including the present global increase. Global temperatures rose by 8°C or so (from a higher baseline that the recent Antrhopocene baseline of ca. 1750 AD). Palms throve at the poles. The equatorial regions were in some cases beyond habitability (although not as hot as during the drying out of the Mediterranean, when local temperatures reached as high as 175°F, but that's another story). But here's the point. There was a lot of extinction, but the global ecosystem did not fail. Evolution actually got a kick in the ass, but if humans were somehow transported to that time, we would have been able to rather easily adapt.


My point is that, even without the mitigation and control efforts we are already beginning to undertake, Climate Change is not a true mass extinction level event. If it did somehow result in the extinction of humanity, it would self-correct in about 1000 years, but that's very unlikely; what's more likely is that we will respond to it, and deal with it. Escape into space will play essentially no role, although of course space technology will continue to develop.


Let me go off on yet another tangent. I regard the evolution of advanced intelligence on earth as just getting started. And it is a fundamental evolutionary development, comparable to the evolution of photosynthesis, oxygen respiration, eukaryotism, sex, multicellularity, or possibly one or two other huge changes in the course of life. Our species is only a vehicle for this change. Just as the first plants no longer exist or have given rise to a whole spectrum of widely diverse descendants, we will give rise to advanced intelligence that is not strictly speaking Homo sapiens, and there is no reason to expect that an adaptation as clearly advantageous as this one will not continue to exist almost literally forever it will give life the ability and opportunity to survive in places other than Earth in the distant future. I am not talking about that here. I do believe that intelligent beings, probably originating on Earth (and perhaps other places) will eventually inhabit the cosmos in general, and in ways we can scarcely imagine. So things like the eventual loss of the oceans from Earth as the sun continues to heat up, which is expected to occur as early as 800 million years from now, are not relevant to this discussion. Why? Because that is so long a time from now that I believe intelligent civilization will have emerged and be thriving in a vast region of space by then, and what happens to one star, and one planet, however historically significant, will be of minor importance.


Anyway, the PETM was the warmest period on Earth, since it happened. Overall, the level of CO2 in the atmosphere was falling pretty continuously since then, and the last 3 million years have been marked by the onset of global ice ages. Partly caused by orbital irregularities, continental positioning, and other factors, but, as various atmospheric and planetary scientists have argued, probably also caused by the gradual failure of the carbon cycle as the Earth ages. Our atmosphere was, until we came along and started burning fossil fuels, actually moving towards a crisis of low carbon. CO2 is essential for plant life, and it is was actually likely, in a few million years, that macroscopic plant life would start failing as a result of ultralow carbon in the atmosphere. But this is a long term trend that would not have affected us that much were it not for our technology. But the point is that, while the Climate Crisis is very real, and if we want to maintain a sustainable world without major disruptions in our societies and civilization, we must deal with it, on a longer term scale, it is an anomaly in a bigger picture that has the Earth's biosphere stressed by cold not heat, low carbon not carbon excess. And in any case, it is not likely to be an extinction level event for our species. (A lot of bad things can happen short of extinction, though, so the technological innovation needed to redress and mitigate the problem is vital). 


And the solutions to the Climate Crisis are going to be implemented on Earth, for the most part, not be escaping into space. I think of this as noncontroversial, but if you have a different view, I'd be happy to talk about it further.