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South5 t1_j3khtod wrote

It has been spoken about for many years that if the Atlantic sea currents were to alter that northern europe would be vastly colder than it is currently.

We have very mild winters in the uk because of the heat of the ocean, we could be like canada or russia in winter without this convection current.

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Redqueenhypo t1_j3lpfx9 wrote

You are at the same latitude as Ontario I believe. It is -2C there now, but 8C in London. You don’t want the Gulf Stream to halt.

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mysteriouskiwi t1_j3mfcqh wrote

Yep, we're really quite high up, but our climate wouldn't really show that. Its very mild. No need for snow tyres or anything as we just don't get that cold regularly enough. Would be a rude awakening to us Brits if our winters went back to what our geological climate would be. Its always suprising when I haven't looked at a map for a while and remind myself that we are up in northern Canada. Just feels wrong haha

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microwaffles t1_j3ncbdz wrote

North American land mass has the unfortunate problem of extending well into the Arctic Circle, so a cold air mass comes down unimpeded if the jet stream will allow it. I don't think British Isles or Europe could ever be as cold as Canada / Northern US

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grumble11 t1_j3mtgag wrote

It is more complicated because the UK is a flat island next to the ocean, with winds blowing from west to east. Oceans moderate temperature even up north. It’ll be colder overall but not as cold as Toronto, which has a continental climate with a lot of mountains and land between the city and the ocean. Maybe Vancouver minus a couple degrees in London?

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kavien t1_j3kvi0a wrote

So, a return to the Middle Ages? Wasn’t there a mini Ice Age during that time?

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Guugglehupf t1_j3kvobt wrote

The Middle Ages where a really long time. There have been cold and warm phases. No real ice age, though.

Last cold spell that lasted a while was in the middle to late 1800s.

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kavien t1_j3l2bi8 wrote

Thanks! I am too lazy to Google sometimes.

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ExtensionNoise9000 t1_j3lahg4 wrote

Last ice age was about 10k years ago if I am not mistaken.

And the last Ice Age animation came out about 7 years ago.

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UniversalMomentum t1_j3lqq3v wrote

We are currently in a ice age I believe it's less than about 2.5 million years.

The easiest definition for an ice age is just whenever there's ice at the poles year round.

We are at the warm cycle of an ice age but also in a hundred thousand year warming and cooling cycle which you can look up as the 100,000-year cycle or the interglacial cycle.

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UniversalMomentum t1_j3lqgzm wrote

More like worse than anything in recorded human history, but also with 2 to 3 times the greenhouse gas levels to spice things up.

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CornucopiaOfDystopia t1_j3lxg7y wrote

Yes, you’re probably thinking of the Little Ice Age, which inundated Europe starting during the Renaissance period:

https://en.wikipedia.org/wiki/Little_Ice_Age

It was theorized to have been caused by a similar reduction in Atlantic currents, though perhaps not nearly as complete as we may be facing ahead. So get some good blankets, Euros.

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philomathie t1_j3l4tig wrote

Probably you are thinking of the maunder minimum, where the sun output less energy. The collapse of the gulf stream would probably be much worse.

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BurnerAcc2020 t1_j3lhj4v wrote

The article says that according to their findings, the Atlantic current does not collapse even by 2300 and even under the worst-case warming (only the Southern one does by that date) but sure, go ahead.

For the record, there was a paperabout the consequences of AMOC collapse in the UK, and they found roughly 3.4 degree cooling. The collapse in rainfall was far more important. EDIT: That paper, which is the one quoted below, was published three years ago and by a completely different group of researchers. Another user thinks the excerpt below is from the study in the article for some reason.

https://www.nature.com/articles/s43016-019-0011-3

> To address these issues, we consider a well-studied tipping point; collapse of the Atlantic Meridional Overturning Circulation (AMOC). The AMOC includes surface ocean currents that transport heat from the tropics to the northeast Atlantic region, benefiting Western Europe, including the agricultural system of Great Britain. We contrast the impacts of conventional (hereafter, ‘smooth’) climate change with those of a climate tipping point involving AMOC collapse on agricultural land use and its economic value in Great Britain, with or without a technological response. > > Our climate projections span 2020–2080 and use a mid-range climate change scenario as a baseline (Fig. 1a–f; also see Methods, subsequent discussion of uncertainties such as weather variability, and sensitivity analysis in Extended Data Fig. 10; the results reported in the main text are mean effects). We take an existing simulation of the effects of AMOC collapse and treat it as a set of anomalies that can be linearly combined with the baseline (smooth) climate change scenario. We nominally assume that AMOC collapse occurs over the time period 2030–2050 (Fig. 1g–l; see Methods). This is a low-probability, fast and early collapse of the AMOC compared with current expectations, emphasising the idealized nature of our study and our focus on assessing impacts. That said, the AMOC has recently weakened by ~15% and models may be biased to favour a stable AMOC relative to observations. > > ...Our remaining scenarios impose a collapse of the AMOC over the period 2030–2050 overlaid on the smooth climate change trend. A previous study that combined a rapid AMOC collapse with future climate projections showed that temperatures will continue to rise globally, but with a delay of 15 years, while British temperatures will be dependent on the AMOC. In the present study, the AMOC collapse reverses the warming seen in the smooth climate change scenarios, generating an average fall in temperature of 3.4 °C by 2080, accompanied by a substantial reduction in rainfall (−123 mm during the growing season. > > Holding real prices constant, in the absence of a technological response (that is, irrigation), rainfall (and to a lesser extent temperature) limitation due to AMOC collapse is predicted to affect arable farming in many areas (Fig. 2f,g). The expected overall area of arable production is predicted to fall dramatically from 32 to 7% of land area (Extended Data Figs. 2 and 3). This in turn generates a major reduction in the value of agricultural output, with a decrease of £346 million per annum (Table 1), representing a reduction in total income from British farming of ~10%. The key driver of the arable loss seen across Great Britain is climate drying due to AMOC collapse, rather than cooling (Fig. 3b,c). This adds considerably to the part of eastern England that is already vulnerable to arable loss due to drying under baseline climate change (green band in Figs. 2b and 3b). Part of eastern Scotland has a potential gain in arable production suppressed by the cooling effects of an AMOC collapse (contrast Figs. 2f and 3c), but the loss of potential arable production due to cooling is small compared with the impacts of drying. However, the assumption of constant real prices is less plausible under the major global food system dislocation caused by a collapse of the AMOC. While firm estimates are not available, substantial food price increases are thought to be likely. With the physical limits imposed by AMOC collapse constraining farm production, such price increases mean that wellbeing losses may be significantly higher than those calculated here, implying that our results should be viewed as lower-bound, conservative estimates of the impacts of such a scenario. > > With a change in technology to implement sufficient irrigation from 2050, the drying effects of the AMOC collapse on arable production could be substantially offset (Fig. 2h,i). In this scenario, land area under arable production still increases from 32 to 38% by 2080, with an accompanying increase in output value of £79 million per annum (Table 1 and Extended Data Fig. 3). Nevertheless, these increases in extent and value are lower than under the second scenario where the AMOC is maintained, due to lower temperatures (contrast Fig. 2b with Fig. 2h). Furthermore, the more extreme reduction in rainfall caused by the AMOC collapse means that water required for adequate irrigation is much greater than under the scenario where the AMOC is maintained. Under the AMOC collapse scenario, 54% of British grid cells now require irrigation, with demand exceeding 150 mm in the growing season for some areas in the south and east of England (and an average demand across irrigated areas of 70 mm of extra rainfall) (Fig. 4). This would require water storage (across seasons) or spatial redistribution across the country from areas of higher rainfall in the north and western uplands of Great Britain. Irrigation costs incurred in this scenario are estimated at over £800 million per year—more than ten times the value of the arable production it would support (see Methods). So, again, irrigation costs outweigh amelioration benefits under climate change—a difference that is massively inflated by the climate tipping point of AMOC collapse. Our analysis also indicates the level of food cost increase (nearly three-quarters of a billion pounds) necessary to justify such irrigation expenditure costs.

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CornucopiaOfDystopia t1_j3ly0sn wrote

Literally not even your own quoted excerpt states that, so why are you posting this? What do you think is meant by your own quoted portion which states,

>In the present study, the AMOC collapse reverses the warming seen in the smooth climate change scenarios, generating an average fall in temperature of 3.4 °C by 2080, accompanied by a substantial reduction in rainfall (−123 mm during the growing season.

Why are you deliberately and confidently misrepresenting the science on this, in multiple parts of this thread?

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AftyOfTheUK t1_j3m5btg wrote

He isn't, at least not in this post.

Perhaps you could quote the thing you think he has said which is misleading? Might help to explain our different understandings of what he said.

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mrbucknut t1_j3me8zp wrote

BurnerAcc2020 didn't misrepresent anything, you just failed at reading comprehension. They correctly state the stated affects by 2300 from the posted article. They then reference another source with a different prediction, and what the worst case scenario is per that quoted article. 2 different articles with different prediction/conclusions, a presented that way. The quoted article is around 2 years older so that is another thing to consider when evaluating both.

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CornucopiaOfDystopia t1_j3mfjkn wrote

But they did it specifically to downplay concerns that they purposefully misrepresented to be about total collapse, when even the parent comment merely and correctly expressed concerns about the current being altered, perhaps as it was when Europe was plunged into the Little Ice Age a few hundred years ago causing terrible famines and extreme cold. To attempt to reframe those concerns as being only about 100% shutdown of the current is an egregious and fallacious strawman of the argument.

But even aside from that, as I said, their own references do not support their implication that the concerns are not appropriate for generations. Just because a study is three years old doesn’t mean that the cause for concern it might raise can be dismissed. There is a clear scientific consensus that thermohaline cycle disruption is a real threat to humanity, with potential for catastrophe well before 2300, and yet reading only the comment I critiqued, one would never know that. That is extremely problematic in a discussion like this one, and I stand by my critique.

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Wouldwoodchuck t1_j3m7of9 wrote

*will be like Canada or Russia…. Insert dog with room on fire meme…

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