The appeal of thinking apocalyptically

There seems to be no limitation to the ability of humans to conceive of ways that their own generation will be the last generation of humans to exist and flourish. I can conceive myself of a myriad of destructive forces that could signal the end of modern civilization. I am not certain that most of them pose us a grave risk in our lifetimes. This does not mean that investment in multi generational solutions is not worthwhile; it simply means that our imagination of time is far too limited. Studies of history would rather quickly show us that many things we take easily for granted are very recent, and that (positive or negative) social changes can happen more rapidly than we anticipate. Studies of other cultures would rather quickly show us some people still don't know of their benefits at all and live at a much more marginal subsistence level. We ourselves often as not have already developed such specialised economies surrounding these benefits that most of us could not replicate them outside of that society of specialisation as we lack any of the required training or aptitude.

Of these world ending scenarios I can think of perhaps four that are worthy of our concern.

1) Asteroids or other large deep space objects colliding with the Earth (or the Moon if they were big enough). - There's a lot of stuff out there and the Earth is a fairly large gravitational influence to pull in objects that pass very close to us. The easiest way to start on this project is to set out to assure we can detect random space particles of asteroids or comets that may pass nearby. And then from there figure out what we would need to do to repel, divert, or even destroy those that pose a greater threat of damaging our environment or potentially impacting near a population center.

2) Nuclear warfare, particularly on a large scale. - There's still enough nuclear firepower in even some of the tertiary nuclear armed countries to annihilate most of human civilisation in minutes. This is to say nothing of the American or Russian arsenals that could (still) do so several times over. The easy way here is to reduce the size of those arsenals overall. That is unlikely for political reasons beyond a certain point. One good incentive of doing so though is the materials used to detonate a large city can also be repurposed to power a large city relatively cleanly, with at least much less of a footprint environmentally than a coal power plant. More countries will occasionally consider this an acceptable possibility.

3) Biological pandemic. - I do not think we're about to have a zombie plague breakout at all, but it is very possible for a virus to wipe out large numbers of people and create a social panic far exceeding the absurd levels of panic we generated over a few religious fanatics and their rejection of modern society via terrorism. We have various methods of response already available to research and cure or treat some diseases. Probably the biggest problem is actually identifying when something is a serious risk of becoming an international pandemic capable of killing or incapacitating tens or even hundreds of millions of people. Even something that could kill a million people a year is a serious problem (and there are diseases that do so right now, but they generally don't have a transmission vector that poses a serious risk to developed societies like the US, so nobody really gives a shit). The tricky bit there is then to do so before it ever reaches that point. And then actually being able to show the counterfactual of mass chaos and biological devastation was true instead of a false alarm.

I think this is somewhat less likely than is historically the case to be a serious concern. Humans live in somewhat more removed circumstances from livestock/poultry (not everywhere), which were the pathogenic sources for killer diseases like smallpox in our past. We also live in a more connected society which means that most of us have been exposed to more varied diseases and developed a broader immune spectrum. Smallpox was still potentially lethal to Europeans but vastly more so to aboriginal peoples in North and South America precisely because these peoples had had no exposure to it and no time to develop it (and in not a few cases, because the Europeans accelerated the plague by spreading it deliberately). Something generally ignored is that the introduction of small pox to the western hemisphere is estimated to have killed off millions of people in less than a century and certainly tens of thousands were dead within a few short years. This is far, far more destructive than AIDS, or Ebola, or even the famous influenza outbreak during the WW1 era as a matter of perspective. Whole villages or towns were wiped out or ceased to function. In order to repeat this, we would most likely require a viral or bacterial agent that acts lethally, spreads easily, and for which humans have no current immunities (meaning it would be unlike other infectious agents). That can happen. Viruses and bacterium can mutate and adapt, and our overuse of antibiotics as a society is not helping by potentially forcing such mutations forward faster than we can adapt our medical knowledge.

4) Global warming. - Of the four of these, this is probably the only one that actually requires amendment of human behavior in any way. It's also probable that unless it generates very catastrophic results (possible), that mostly richer countries could adapt to climate changes and circumstances without a major impact on well-being and lifestyle for most of their citizens even as climate is shifting. The problem isn't the billion or 3 people living in the rich or near rich world. It's the other 3-4 billion who are living in societies that are closer to subsistence levels or abject poverty. Their lives can be ended, their countries destroyed or chaotic, and so on. I regard that as a very serious matter that people of Bangladesh would be impacted and it does not seem sensible that we should do nothing as a society or individually in response. But that leads to the actual and more sensible debate, "so, what do we do about it now?"

I've seen or encountered a lot of arguments and they come from both the local, individual level, and the societal, governmental level.

• Stop burning coal. Easier said than done, but I agree. Coal is the most bad option here to power a modern society used in large amounts. To do so you'd have to change the price of burning coal to be less profitable ALL over the globe, not just here, where coal use is actually going down already, or change the price of alternative fuel sources (natural gas for example) to be cheaper options. 
• Use and fund alternative energy projects. I suspect a far stronger argument could be to stop funding "dirty" energy projects or fuel use with substantial subsidies first rather than trying to redress this balance by funding yet more energy projects. 
• Apply some kind of externality (as "net zero" income tax) onto existing fossil fuel consumption and sale. For the most part if we could pass a pretty clean bill to do this, and the tax wasn't used to build new infrastructure (unless it is upgrading existing infrastructure or a distribution system for new or cleaner fuels), this would be my favored approach at the policy level. I have little confidence such a bill would be clean and that there would be all manner of carve outs. The basis for this working would be that most people could avoid the tax by reducing their individual energy footprint, which in turn should make it easier to pay for any consequences of climate shifts as they may be reduced (and thus less tax would need to be raised). 
• Localvore food consumption. For the most part I think this is a silly idea and that it may even be counterproductive environmentally. Maybe not on climate change but on water pollution from agricultural run-off of nitrates or disease vectors from using manure. Which in turn requires feeding and care of large animals, who themselves are a considerable source of pollution. I think this argument rests on several concerns; that trade from elsewhere is somehow inefficient, which is usually false, I see no problem if I have to buy my grapes from California or Chile and I am greatly improved as an individual to have a large array of possible produce and meat to sample and enjoy in my daily meals. We are all also greatly improved to buy things from other people by selling them things that we are ourselves effectively producing rather than trying to consume them all ourselves. Trade works and is almost always a good in improving our lives to let things be grown or produced in places that can do so far more effectively than we can ourselves. The major flaw of that argument is it dramatically underestimates that the environmental impact of modern agriculture is almost entirely at the production stage (especially for meat), and not at the shipment, storage, and distribution stage. Which is pretty small for most things. Even if it is not zero, it is the act of large scale farming (even local farming) that does most of the work. It is generally more efficient and much less damaging to have a large farm, even a local one, going out and fertilizing and producing food and flora and fauna for sale than to have lots of people gardening. The reason people should garden should not be that they believe they can save the planet. The reason should be that it is something they enjoy doing or enjoy the (literal) fruits of. As related concerns, many people have gone into buying things that are "organic" or "natural", with similar environmental justifications that are usually equally flawed. The reason human beings should consume these things in their diet has little to do with the environment and more to do with the fulfillment they receive from production of the food stuffs and the overall reliability of the food chain if they feel they know where something came from rather than an impersonal package of meat or vegetables. If the environmental impact is, as I think it is, actually somewhat negative, it's fairly negligible at the individual level to have a garden versus trying to buy local produce from farms that can be grown half way around the world for a quarter of the environmental cost. 
• At an individual level many people may seek to reduce their energy use, or to use alternative sources of energy themselves. Unfortunately there appears to be a large signaling effect at play rather than an effective result. People and companies sometimes install wind turbines that have to be powered to spin because there is inadequate wind to turn them most of the time, and then wastefully power them anyway. Solar panels are more frequently deployed on the side of the house or business facing the street, regardless of whether that is the side which would generate the most electrical power. Recycling rates are far more likely in the US to be reasonably high if the collection of recyclable goods and materials is public. People who own more fuel efficient cars on average drive them more often which leads to larger traffic snarls and jams, which in turn leads to more pollution and higher energy consumption rates, for not only themselves but for other drivers. Governments respond to this last by building more roads, which paradoxically can increase traffic and energy use further by providing more routes, if not also more destinations. 
• By far the most significant thing at an individual level (here at any rate) that could be done is to do away with the home mortgage interest deductions in the US (actually this is government having to do something, but it would change individual behavior significantly). This would help to encourage urban density instead of suburban life; which nobody seems to actually want so much as they may find the cities unpleasant right now. We would need some governmental actions to reduce rent controls or property constraints such that more people could live vertically, thereby reducing commuting and concentrating our energy demands, densifying populations and destinations to make public transit much more viable, and so on. 
• Tax congestion on roads by instituting variable tolls on controlled access roads (highways). 
• We may want to combine that with an effort to allow for more telecommuting work and flexible scheduling. 
• Another strong individual level constraint would be to have more energy efficient objects, put in insulation, design homes and offices to be heat/cooling efficient, unplug things more often, compost food waste, and so on. Most of this is invisible and inconspicuous consumption. That makes it difficult to signal. Which implies that maybe we need conspicuous signs that we've done it that come along with these projects and maybe more people would investigate these options. 
• Geo-engineering experiments to alter weather or sunlight absorption patterns. These are uncertain, but in my view are at this rate the most likely options to proceed forward and be carried out, somewhere, by someone. 

The individual arguments arise primarily out of frustration that the societal level few things are being done. I find that there are two basic attitudes to really any large scale societal issue.

1) Most people expect someone else to do all the work of fixing it. This may be a consequence of specialisation. Climate modeling or weather and climate analysis and geological histories are complicated subjects and can involve a great deal of the dreaded "math". It is assumed that because this is a "science" problem, that scientists will solve it for us. In repeated polls I think the average American expects that whether we are faced with a plague or widespread drought and heat waves/cold snaps from climate shifts, we would have smart people somewhere stashed working on solving the problem and they would invent something that wouldn't require us, as individuals, to really fundamentally alter how we live in a "negative" way. Innovation must be a part of our problems and their solutions, but innovation sometimes requires that we will eat some vegetables for a while before it gets into the wild as a tamed beast with applications ready to go. It is not as clean and tidy as is believed, and it often involves an iterative process of fits, starts, failures, and restarts. And then even if it is ready to get something off the ground and working, someone could try to squash it politically anyway. 

2) Everyone else then basically expects that somehow nobody will ever do anything about a major problem at a large enough scale and that preparation for imminent disaster and societal collapse is an immediate priority. Or if not taken on that scale, that we should adopt fairly radical and often ineffectual behaviors to moderate our worst and most destructive impulses, without properly and empirically seeking out a way of identifying what those are. In other words, "we should all do what I say, because I don't like X." Whether or not X is actually a problem or not or whether solution Y is itself any more desirable is not important to discuss. The important thing is to be seen as "doing something" about the problem, and often as a corollary to loudly proclaim that whatever that something is, it's probably what you are doing about it.

The advantages of both of these systems is that it allows the measure of blame to be mostly shifted away. And for complex scenarios for which the individual's merit and demerit is very small, elections, pollution, water or antibiotic overuse, etc, it is in fact the case there isn't much incentive to making significant changes in your own behavior.

The question mark is what happens when the cumulative incentives are bad such that little or no change is made, in an area something must be changed or calamities are at risk of occurring. The best bet is to look for a way to change the game and rig the incentives. But if we think we're about to destroy the world and no longer have the incentive of "future generations" toward which we are abstractly connected through children or grandchildren, nobody has any incentive to change the game. They actually have a strong incentive to hold out for a better deal to do what they want. Apocalyptic thinking is the self-important way to examine the situation, the flexibility of the status quo, and determine (or pre-ordain really) that the world probably won't spin on without me and my kind in it anyway, so why should I care what happens to it now.

This is a reality based outgrowth of my disdain for the common belief in supernatural afterlives. The world is here, now. We have some responsibility to do things with the people in it, and to interact and attempt, if often poorly, to share their concerns and affections. The thinking that the world won't be here tomorrow, or that there's some better world out there instead, destroys these moral obligations to one another in the face of potential catastrophes. It may accelerate their comings and goings rather than give us breaks and stops on that path.