I've read more science fiction and fantasy in my life than most people have read, anything at all. I've also written a fair amount, and I tend to take anything that happens on a global scale and extrapolate it with your classic storyteller's habit of "let's just image what would happen if this...?"
In this instance I'm asking a single short question: How many simultaneous volcano eruptions would it take to bring all world air travel to a grinding halt?
I mean, we have plenty of these suckers all over the place; and enough of them would be able to spew enough crap into the atmosphere at the right levels, so that the plumes, driven by the air currents, drift across sufficient strategic areas to stop all travel by just about all aircraft—just just jets, but even those flying close to the ground. No more rescue helicopters; no more emergency help to anything that isn't reachable by road or ship. And even road travel could be an issue, because this volcanic ash doesn't just clog up jet engines. Oh, yes, and it kills people, too. Iceland will have so many people dying as a result of this, that it may amount to a virtual Icelandic genocide. Not in the immediate term, but this stuff is lethal. Might as well inhale some Cobalt 60 from some terrorist lunatic's dirty bomb.
Air travel relies on comparatively clean air. The occasional bird strike is bad enough, but it seems that it's so common, that engines have been built to cope with a lot of it. Shredded crispy meat, bones and feathers don't do engine blades any good either, but they're survivable. Fine volcanic ash, on the other hand, means you can probably kiss your jet engine goodbye. Meaning that the airlines are going to wait a long time before they fly in European airspace again, because if they're not, the cost to replace hardware, including such sundry items as windshields and paintwork, will be higher than that of lost revenue. Not taking into account that the abrasion on the leading surfaces of wings could result in major re-work there as well. It won't take a lot of dust to do damage here, and there are few indications, at the time of writing this, that what dust there is, will continue to spread and do its dirty work even further afield. And, of course, eventually it'll need to settle somewhere. Meaning someone's going to breathe it in. I guess the argument is that if the quantity is sufficiently small, we'll be all right. True enough, but the larger the quantity, the larger the area over which it needs to settle to be 'thin' enough. Rain would help, of course, but as you know, it never rains when you need it.
In Australia we also have volcanoes on our doorstep, in Vanuatu, some of which are just waiting to blow their heads off. We're more concerned here—those not in denial, that is; the rest doesn't even know that these things are there—about tidal waves, which could be huge from those particular volcanoes, and which would reach the Eastern shores of Australia within 2-3 hours; hardly enough time to even sound an evacuation alarm. Another excellent reason not to live on the coast; not in low-lying areas anyway. We're not quite so worried about ash fallout, since the air currents tend to be on our side and will blow the stuff away from, rather than toward us.
So, back to the question I started with. How many volcanoes would it take? And what would be the effect on...well, on just about everything. And are we going to learn anything at all from this? Or are we going to wing back into the air as if nothing had happened? Heads firmly in the sand? Are we going to ignore the potential for global logistic, economic disaster—not to speak of the unhealthy addition of this factor into the Global Warming equation—that this presents?
I think so. I think we're going to proceed as Obama did, when he presented his recent PR campaign speech to NASA in which he promised we'd go to Mars in 25 years—but which totally neglected the real reason why we need to be in space and be there ready and waiting—not for tiny particles, but for the real big ones. People will waste their time and endless resources on Global Warming issues, rather than, say, investigating methods of air transportation that are comparatively immune to such issues as volcanic eruptions.
The science fiction writer in me is already penning a story—don't have the time, but maybe someone will take this and run with it—where indeed a lot of volcanoes have blown their tops, but slowly enough, so that the aircraft industry has actually had time to rediscover the blimp—a.k.a. 'Zeppelin' or 'Airship'—as a viable alternative to the currently-in-vogue jet. In doing this they also found that blimps actually emit far less greenhouse gases, and so are beneficial in more ways than just one. They just don't fly at high speeds, so your average executive-in-a-hurry would just have to learn patience. Too bad, eh?
Would it be too much to ask for aircraft designers to spend just a few more extra thoughts on the subject?