I had a little bit of fun with the idea of future apocalypses to celebrate the non-apocalypse of 12/21/2012. Now that apocalypses are passe, I’d like to come back to the idea of environmentally induced apocalypses in the deep future. I’m nothing if not unfashionable.
One good place to look for such disasters is Wikipedia, specifically the article on Ice Ages, and even more specifically a little graph about halfway down, on daily insolation at the top of the atmosphere at 65 degrees north on the summer solstice. I’ve reproduced it below.
Now, I’m not a climatologist, but I’m not entirely ignorant, so I’ll attempt to explain this. Insolation is the amount of energy coming in at the top of the atmosphere. Sixty-five degrees north is pretty much the Arctic circle, and the summer solstice is the time of maximum sunlight. The general idea here is that times of low insolation coincide with ice ages, and the reason there is variation is due to orbital changes due to Milankovitch Cycles.
Now, this isn’t THE explanation of ice ages, because Milankovitch cycles have happened for the past 4.5 billion years. In most times, they don’t apparently result in Ice Ages. Occasionally they do. Other factors such as the position of the continents and the number and size of rapidly rising mountains (which take carbon out of the air through the silicon cycle) also matter. Beyond that, there are (of course) arguments about whether this is the most important value, or whether other factors are more important. Since we’ve got extremely complex models and imperfect climatological record, the arguments about the mechanisms behind ice ages are going to be argued for a very long time.
Despite that, let’s assume that the insolation graph is important, and that when the amount of energy coming in changes dramatically, the climate changes dramatically. Let’s also assume that a rapidly changing climate is generally bad for global civilizations like ours, and that inflection points are good for civilization, because the climate is stable at those points. The logic here is that a rapidly changing climate means that everything (plants, animals, and humans) has to move, because many formerly hospitable areas become less habitable, infrastructure breaks down, and so on. Conversely, stable global climates promote civilizations that create ways to take advantage of a climate that stays moderately stable for a few centuries, whether it is stably hot or stably cool.
In the above graph, between now and 400,000 CE, there are, by my count, 35 peaks and valleys. Each of these is somewhere between 500-1000 years long, which is about how long our civilization has expanded. Ditto with the Romans, come to that.
I’d suggest that we’ve got a very good candidate for our apocalypses here. The apocalypses are the slopes, where insolation changes substantially and keeps changing. At the start of each slope, a civilization that has lasted for centuries suddenly has to radically reinvent itself. In most cases, I’d suggest the result will be a dark age, likely an age of migrations. Sea level will fluctuate, deserts will become grasslands or vice versa, jungles will spread or contract, and so forth, and people will have to move. In my book, that’s an apocalypse for every culture ended by the crisis, although humanity will never be in danger of extinction.
I should point out that what we’re doing with our MegaBelch of gigatonnes of carbon will cause climate to change much faster than what we’re talking about here. If we really go for it and release 5000 GT of carbon in the next two centuries, it will take over 1000 years for sea level rise to max out (at about 100 m above current coastlines), although we’ll reach maximum temperatures in “only” a few centuries after the MegaBelch enters the atmosphere. This is really fast climate change, and while it will be slow in our lifetimes, It appears to be worse than anything on that insolation graph. Appears is the proper term, since I’m comparing the effects of carbon in the atmosphere to sunlight coming in, which is definitely comparing apples to orange groves.
Another caveat is that I’m ignoring all the black swans and most of the gray ones when it comes to future events. I haven’t factored in the megavolcanoes that are undoubtedly going to erupt during the next 400,000 years, nor am I factoring in city killing asteroids (we will get hit multiple times), and giant landslides like the East Kilauea rift, which will raise a gigantic tsunami when it inevitably slides into the Pacific. I can handwave this away by saying that such disasters are more damaging if they hit a globalized civilization, much less damaging if they hit in the middle of a dark age. As the WWII Siege of Stalingrad and the modern wars in Afghanistan have shown, once the infrastructure has been destroyed (which is relatively easy), it’s much harder to wipe out the people who are still living there. Pounding a city reduces it to rubble, but pounding a rubble pile just makes more rubble. On a humanitarian level this is horrendous (and it is not an excuse to keep from rebuilding Afghanistan or other failed states), but it is nonetheless true. A society that keeps its people comfortable is more fragile than one which has to endure disasters on a regular basis.
Regardless climate will continue gyrating into the deep future, however much carbon we blow into the air, and people will live through these changes. On the warm side, the global climate will most likely look like the late Paleocene or early Eocene. On the cooler side, it will look like the Pliocene, at least as long as there is surplus carbon in the air. After perhaps another 500,000 years, our carbon surplus will be gone and we’ll be back into the ice ages proper, with ice free poles in the interglacials and enormous glaciers during the intervening ice ages. Humans will survive, but I suspect our future on this planet is going to be a long history of lost high civilizations, fallow ages, and civilizations rising again during the times climates stabilize.
To put it simply, We Are Atlantis 1.0, and something like this is more likely to be our future than any singularity.