Gentle Decline 1/23: Streams & Snows

Hello. In this issue, I'm spending a while looking at another possible outcome of climate chaos, which is the counter-intuitive scenario where Europe gets colder, if the Gulf Stream shuts or slows down, and what we'd need to do to live in those conditions. This was a major consideration of climate crisis outputs in the late 1990s and early 2000s, and seems to have mostly disappeared from public thinking since.

Welcome! to all the new subscribers, many of whom seem to have arrived in from nothing here, which quoted from and said nice things about a recent issue of Gentle Decline. There's a backlog of issues which you can get to on the tinyletter site, and I'm told they make reasonably coherent reading if you work through them in order. In other housekeeping stuff, I was absolutely astounded by the response to my setting up a ko-fi account. Thank you very much indeed to everyone who contributed; it makes things a notch easier in a time when I'm otherwise out of work.

So first, let me be very up-front about this: nobody really knows exactly how the Gulf Stream affects climate in Europe. It's fairly evident that it does; Western Europe is warmer and more generally temperate than other places at this latitude, and the Gulf Stream carrying warm water (and possibly some warm air, too) from the Caribbean is a clear enough explanation for this. However, since it has always been there (for human values of "always"), we don't have an "off" state to which to compare it. There's plenty of analysis and theory out there. But the differences between models are pretty impressive, and I'll get to those as I go.

The main reason this is an issue is the Gulf Stream, rather than running on pure Coriolis force (movement in fluids caused by the Earth's rotation), also depends (or is thought to depend) on something called thermohaline circulation. Basically, the salty water coming up from the south is 'heavier' and sinks when it cools in the North Atlantic, forming a new deep current which flows back southward. But now icepacks in the Arctic are melting, which pushes lots of fresh water (ice does not contain salt) into the North Atlantic, which dilutes the salty southern water, and prevents it from sinking. Once it doesn't sink, there's no "pull" for the current, and so it slows down, or stops. Evidence suggests that there has already been a slowdown in the current. While there really isn't a consensus on this, current best thinking seems to be that the current won't stop because of this effect, but it will become much slower. Slower-moving water has more time to cool, which will both accentuate the slowing effect, and take away some of the warmth that would otherwise be arriving in the northern latitudes.

It's not clear (there's a lot of not clear in this) on what timescale this would have effects. One study indicates that a previous (not recent, except in geological terms) shutdown of the current didn't have an effect until some 400 years had passed. Others seem to think that there are already effects. Some 'skeptics' think there will be no effect at all. I'm completely unconvinced by the latter, since the idea of a massive ocean current changing having no effects on the land around it seems like nonsense, but I don't know enough to have a real opinion on the differences between the other models. I'm going to assume, for purposes of the rest of this issue, that there will be effects, they won't be too severe, that average temperatures will as a consequence of this drop by a small amount in Western Europe, and that the humidity we're all too familiar with in the Isles will decrease as well. In addition, the prevailing winds will shift slightly, so that we get more easterlies and fewer westerlies.

The first effect of this would be that the Isles, the Low Countries, and Western France would be distinctly colder, on average. This doesn't mean we wouldn't get summer heatwaves - it seems pretty clear that those are a guaranteed feature of the next few centuries - but we'd also get colder winters, or more cold snaps during winter. Iberia will probably escape this effect, and there seem to be a few theories out there that say that the Gulf Stream slowing down, and thereby not dragging cold south-bound water past the coast might even warm Portugal up a bit, which I feel is possibly not great news for Portugal, either.

Norway might get some colder bits of winter, but is already pretty well set-up to handle that, and the difference between a cold snap of -20C and one of -25C or -30C is actually not all that huge; unless you get to seriously colder temperatures, frozen solid is frozen solid. Sweden is sheltered by Norway, and the Baltic is very little affected by the Gulf Stream, so the Swedish east coast, Finland and the various other North European countries that have Baltic coastlines will be less affected. Denmark falls between, with the west coast affected and the east coast less so, probably.

In practice, in the areas affected, we'd be looking at colder cold snaps in winter, with a greater likelihood of snow in the Isles - particularly on the east coasts, where easterlies coming across the North Sea and the Irish sea can give lake-effect streamers of snow showers. Conditions like the now-legendary Winter of 2010-11 (and the more recent heavy snow of March 2018) would happen more often.

Neither Ireland nor the UK is set up to handle this at present. The affected parts of the continent get weather like this more often already (though not frequently) and so have some of the infrastructure in place for it. Essentially, what would be needed are properly insulated pipes, buildings with airlock-style doorways, covered or underground walkways where there's high foot traffic (car parks to railway stations, and the like), snow ploughs, and spaces into which to push (or transport) the ploughed snow. None of this is new technology; all of it is visible in use in the Nordic countries and in Canada.

While the Isles do have winter crops that will be affected by these outbreaks (and lambing season in livestock), it's mostly a matter of magnitude rather than anything else. Winter isn't a growing season per se, and overwintering crops can usually survive under frost or a blanket of snow without much harm - it's only if the ground is frozen for long stretches of time that crops have issues, as I understand it. As long as the conditions are just more frequent and/or colder cold snaps, they'll be ok.

In terms of what people would need to do to handle this, there are the short-term efforts for handling a cold snap in a place that's not set up for it (which look remarkably like pandemic handling, with the addition of making sure you have a way to keep warm in the case of a power cut), and the longer-term efforts of changing infrastructure and supplies to cope. Water pipes are the big one here, to be honest - both the UK and Ireland have aged, leaky, downright dodgy networks of water mains, which can't cope at all with freezes, let alone severe ones. In addition, household supply pipes are often not buried deeply enough to avoid freezing - we had that issue in December 2010, because as we later discovered when in the course of other work we dug up the driveway, ours was running only barely below the concrete surface.

There are also possible issues with electrical supplies, for two reasons. First, there's straight-up demand on the network, as electrical heating is run 24/7 for a while, and that can cause brownouts. Second, where there are overhead wires supplying power (and presumably phone connections, too) accumulated ice can bring them down. Brownouts are not a frequent issue in Ireland, at least; our grid seems to be reasonably resilient. Overhead wires become less common all the time, with buried cables being the norm in almost anywhere built after the 1970s, and retrofitted in many other places.

Annoyingly, oil and gas heating also rely on electricity to actually run. But almost all houses in the Isles still have at least one fireplace or solid-fuel stove, which provides a fallback heating mechanism if all else fails. Unfortunately, this isn't true for apartments, and a lot of those have been built in the last few decades (I'm coming to a conclusion that apartments as built in the Isles really aren't suitable for much beyond the sleep-and-store-stuff function). Provision of the fuel for those fireplaces is another issue, of course; firewood is more of an aesthetic supply right now, much like candles, and coal and turf are being discouraged where possible. Should this cold-climate thing come to pass, people are going to want more fires anyway, and there will be some definite money to be made in firewood supplies. The amount of firewood that can come out of an acre of coppiced ash trees, for instance, is actually staggering.

Retail supply lines will need to adjust, but that's not all that difficult once the cold weather is frequent rather than exceptional. And once people get used to the weather, there'll be less in the way of panic buying. We'll need actual winter tires for cars, which hasn't really been a thing before, but again, the Nordic countries have that already.

In the case that the models are wrong, and the climate gets colder in general in North-Western Europe, then we'll have some different issues. Agriculture will have to shift toward the summer-only Nordic models in the Isles, maybe using more greenhouses, and the Nordic countries themselves are going to have an even short viable growing season, effectively shifting climate bands a few hundred kilometres south. As the majority of agriculture (and indeed population) is the southern ends of most countries there, this should't result in a lot of displacement. Isles houses will need better insulation, and there will be different demands on power and water infrastructure.

These aren't bad scenarios for me personally; I love the cold, and I don't function well on hot or sunny days. But, to be completely honest, there are two factors mitigating against these things happening. First, the likelihood of the Gulf Stream slowing affecting climate that much seems to be fairly low. It has already slowed by a measurable amount during the 20th century, and it hasn't had much effect on our climate at all. Second, even if it were to stop completely instead of slowing, the warming processes already at work in the atmosphere would counter the effects, and the only change from our point of view would be slightly drier weather in the Isles and alterations in fishery and other oceanic conditions. That would have its own knock-on effects; water shortages and more need for irrigation, but all of that is manageable, unlike the various areas of the world where water is running out.

Broadly, though, it seems as if this particular possibility within the overall mess of climate chaos would either help, locally, or not do a lot, at least in Europe. I haven't looked at the effects on the US East Coast, or indeed the Caribbean, mostly because I honestly don't know what they might be. A guess: the Caribbean might get even warmer, since some of the heat there is not being drawn away by the current, but it's unlikely to get to Arabian/Indian levels of heat because of the presence of so much water. The East Coast would presumably have even more wintry weather than it already does, but like the Nordic countries, is already equipped to handle that. So overall, it's kind of a non-event - which, frankly, is something of a relief in view of everything else happening.

This issue brought to you by the ongoing Irish lockdown and my apparent attempt to deal with it by writing non-stop, the after-effects of digging a 30cm-deep carrot bed in one afternoon, and a lot of reading about Doom, the Coming Apocalypse and the Long Emergency, etc. The next issue is, I think, going to start looking at the issue of oil supplies in the context of ongoing climate crisis, because there are plenty of indications that the timing on that is going to suck.

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