4 ms·

Is the Atlantic Overturning Circulation Approaching a Tipping Point?

72 points by Anon84 3y ago

FrustratedMonky 3y ago
Perhaps, could it happen "The Day After Tomorrow". EDIT> No need to worry, we have until 2100. "The Coriolis force pushes moving water, in this case, in the Gulf Stream, to the right, away from the American coast. When the Gulf Stream weakens, less water is moved northward, causing water levels to rise inshore of the Gulf Stream, with models projecting a 15–20 cm rise by 2100 from this effect alone" It will be pretty uncomfortable to live in Europe. Super Hot summers. EDIT 2: There is reference to Europe being hotter in the summer "The current cold blob is already affecting our weather, though not in the way that might be expected: a cold subpolar North Atlantic correlates with summer heat in Europe (Duchez et al., 2016). The cooling of the sea surface is enough to influence the air pressure distribution in a way that encourages an influx of warm air from the south into Europe. "
- 77pt77 3y ago
  Another guy here just wrote it would be covered by a glacier.
  - FrustratedMonky 3y ago
    It might be transitory. Like next few decades, hot because of low pressure allowing hot southern air to move north, but long term, cold as the ocean temp drops further?
  - relaxing 3y ago
    Europe’s pretty small, but it can still be both hot and cold in places.
  - ivanhoe 3y ago
    It's true for the most of the North and West Europe as all Atlantic and Baltic areas will get significantly colder. Southern and Eastern Europe will get significantly warmer, on the other hand. This will also drive the weather systems a lot more unstable within the whole Europe, so it's a bad news for everyone there.
hedora 3y ago
This is a long article, and they take a long time to summarize their conclusions: > In other words: we are talking about risk analysis and disaster prevention. This is not about being 100% or even just 50% sure that the AMOC will pass its tipping point this century; the issue is that we’d like to be 100% sure that it won’t. That the IPCC only has “medium confidence” that it will not happen this century is anything but reassuring, and the studies discussed here, which came after the 2021 IPCC report, point to a much larger risk than previously thought. There are some maps towards the bottom of the article. To summarize: If the Atlantic currents do collapse, Europe will likely be covered by a glacier. Fossil records and computer models agree this could happen in our lifetimes. I first heard the alarm being sounded over this in the 1990’s (based on fossil records). The last time this happened the process took 50-100 years to flip Europe from normal to ice age.
- deleted 3y ago
  [deleted]
- bradrn 3y ago
  > If the Atlantic currents do collapse, Europe will likely be covered by a glacier. I think you misread the article here. Looking at Figure 15 (temperature change caused by a total AMOC collapse), it appears that Britain, Iceland, Scandinavia etc. would cool by around 2°C, whereas the rest of Europe warms by roughly the same amount. The consequences of such a strong temperature gradient are worryingly hard to predict, but don’t involve Europe being ‘covered by a glacier’. (Scandinavia, maybe? But not most of Europe.)
  - zarzavat 3y ago
    Is that 2 degrees of cooling gross or net the predicted warming? i.e. is that 2 degrees below pre-industrial levels, or is it x-2 where x is warming due to global warming ≈ about pre-industrial levels.
    - hedora 3y ago
      The last time this happened, the glacier reached France and Germany.
alephnerd 3y ago
So Lisbon will finally become a replica of San Francisco... /s [0] Basically, European cities will have similar weather to cities West of the Rockies. So London will share temperatures with Vancouver overtime, and Oslo with Anchorage. It would be a massive regional climate catastrophe, but worst case, at least European countries are rich enough to support the infra changes needed. Silver lining, it would create a West African monsoon that would restart Saharan greening and push back desertification in the Sahel, but would suck for Egypt as most of their wheat comes from Russia+Ukraine, which would have shorter sowing seasons, but then again their climate would change to that of Southern Alberta+Saskatchewan. But then again, might have positive effects for the Amazon [1] Edit: that said, it appears that ICPC's AMOC model seems to have some issues with backtesting [2] All the more reason to err on the side of caution and ensure the status quo remains and the AMOC continues. [0] - https://www.nature.com/articles/s41467-023-39810-w https://www.nature.com/articles/s41467-023-39810-w [1] - https://www.nature.com/articles/s43247-023-01123-7 https://www.nature.com/articles/s43247-023-01123-7 [2] - https://royalsocietypublishing.org/doi/10.1098/rsta.2022.0193 https://royalsocietypublishing.org/doi/10.1098/rsta.2022.019...
bradley13 3y ago
If the Atlantic currents do collapse, Europe will likely be covered by a glacier There is no equivalent current in the Pacific. Yet, the Pacific Northwest is not covered by a glacier. It's not the currents, but simply being next to (East of) an ocean that matters.
- shagymoe 3y ago
  I'm going with the scientists on this one, not some random dude on HN.
- el_nahual 3y ago
  London is further north than Winnipeg.
deleted 3y ago
[deleted]
mitjam 3y ago
I think the most actionable summary is this: For the AMOC and other climate tipping points, the only action we can take to minimize the risk is to phase out fossil fuel use and stop deforestation as fast as possible. If we can reach zero emissions, further global warming will stop within years, and the sooner this happens the smaller the risk of passing devastating tipping points. It would also minimize many other losses, damages, and human suffering from “regular” global warming impacts (e.g., heatwaves, floods, droughts, harvest failures, wildfires, sea level rise), which are already happening all around us even without the passing of major climate tipping points. I think they are right and still feel the urge to pretend it’s not happening or not affecting us so much so I can go on with life. This is probably the main problem. When we will finally feel enough pressure that it hurts so bad that we cannot ignore it anymore, it might be too late. Those tipping point frighten me even more than the gradual warming.
- ndsipa_pomu 3y ago
  It's quite scary that a lot of people don't take the risks of climate change seriously and instead wring their hands about the disruption that the phasing out of oil will cause. That's nothing compared to the disruption, famine, deaths and wars that will result from climate changes - just imagine a world where North America is in severe drought and most of Europe becomes unable to grow food or to live in without air conditioning.
  - jfengel 3y ago
    They're convinced it's a hoax. They don't have to worry about trade offs. Burning more fossil fuels is all upside and no downside. We can publish all the articles we want on the magnitude of the problem. As far as they're concerned it's all evidence of the conspiracy.
jnxx 3y ago
I am aware that reports on the topic have been submitted before. This is a fantastic, well-written article by world-class climate scientist Stefan Rahmstorf.

72 points by Anon84 3y ago

Perhaps, could it happen "The Day After Tomorrow". EDIT> No need to worry, we have until 2100. "The Coriolis force pushes moving water, in this case, in the Gulf Stream, to the right, away from the American coast. When the Gulf Stream weakens, less water is moved northward, causing water levels to rise inshore of the Gulf Stream, with models projecting a 15–20 cm rise by 2100 from this effect alone" It will be pretty uncomfortable to live in Europe. Super Hot summers. EDIT 2: There is reference to Europe being hotter in the summer "The current cold blob is already affecting our weather, though not in the way that might be expected: a cold subpolar North Atlantic correlates with summer heat in Europe (Duchez et al., 2016). The cooling of the sea surface is enough to influence the air pressure distribution in a way that encourages an influx of warm air from the south into Europe. "

77pt77 3y ago
Another guy here just wrote it would be covered by a glacier.
- FrustratedMonky 3y ago
  It might be transitory. Like next few decades, hot because of low pressure allowing hot southern air to move north, but long term, cold as the ocean temp drops further?
- relaxing 3y ago
  Europe’s pretty small, but it can still be both hot and cold in places.
- ivanhoe 3y ago
  It's true for the most of the North and West Europe as all Atlantic and Baltic areas will get significantly colder. Southern and Eastern Europe will get significantly warmer, on the other hand. This will also drive the weather systems a lot more unstable within the whole Europe, so it's a bad news for everyone there.

hedora 3y ago

This is a long article, and they take a long time to summarize their conclusions: > In other words: we are talking about risk analysis and disaster prevention. This is not about being 100% or even just 50% sure that the AMOC will pass its tipping point this century; the issue is that we’d like to be 100% sure that it won’t. That the IPCC only has “medium confidence” that it will not happen this century is anything but reassuring, and the studies discussed here, which came after the 2021 IPCC report, point to a much larger risk than previously thought. There are some maps towards the bottom of the article. To summarize: If the Atlantic currents do collapse, Europe will likely be covered by a glacier. Fossil records and computer models agree this could happen in our lifetimes. I first heard the alarm being sounded over this in the 1990’s (based on fossil records). The last time this happened the process took 50-100 years to flip Europe from normal to ice age.

deleted 3y ago
[deleted]
bradrn 3y ago
> If the Atlantic currents do collapse, Europe will likely be covered by a glacier. I think you misread the article here. Looking at Figure 15 (temperature change caused by a total AMOC collapse), it appears that Britain, Iceland, Scandinavia etc. would cool by around 2°C, whereas the rest of Europe warms by roughly the same amount. The consequences of such a strong temperature gradient are worryingly hard to predict, but don’t involve Europe being ‘covered by a glacier’. (Scandinavia, maybe? But not most of Europe.)
- zarzavat 3y ago
  Is that 2 degrees of cooling gross or net the predicted warming? i.e. is that 2 degrees below pre-industrial levels, or is it x-2 where x is warming due to global warming ≈ about pre-industrial levels.
  - hedora 3y ago
    The last time this happened, the glacier reached France and Germany.

alephnerd 3y ago

So Lisbon will finally become a replica of San Francisco... /s [0] Basically, European cities will have similar weather to cities West of the Rockies. So London will share temperatures with Vancouver overtime, and Oslo with Anchorage. It would be a massive regional climate catastrophe, but worst case, at least European countries are rich enough to support the infra changes needed. Silver lining, it would create a West African monsoon that would restart Saharan greening and push back desertification in the Sahel, but would suck for Egypt as most of their wheat comes from Russia+Ukraine, which would have shorter sowing seasons, but then again their climate would change to that of Southern Alberta+Saskatchewan. But then again, might have positive effects for the Amazon [1] Edit: that said, it appears that ICPC's AMOC model seems to have some issues with backtesting [2] All the more reason to err on the side of caution and ensure the status quo remains and the AMOC continues. [0] - https://www.nature.com/articles/s41467-023-39810-w https://www.nature.com/articles/s41467-023-39810-w [1] - https://www.nature.com/articles/s43247-023-01123-7 https://www.nature.com/articles/s43247-023-01123-7 [2] - https://royalsocietypublishing.org/doi/10.1098/rsta.2022.0193 https://royalsocietypublishing.org/doi/10.1098/rsta.2022.019...

bradley13 3y ago

If the Atlantic currents do collapse, Europe will likely be covered by a glacier There is no equivalent current in the Pacific. Yet, the Pacific Northwest is not covered by a glacier. It's not the currents, but simply being next to (East of) an ocean that matters.

shagymoe 3y ago
I'm going with the scientists on this one, not some random dude on HN.
el_nahual 3y ago
London is further north than Winnipeg.

deleted 3y ago

[deleted]

mitjam 3y ago

I think the most actionable summary is this: For the AMOC and other climate tipping points, the only action we can take to minimize the risk is to phase out fossil fuel use and stop deforestation as fast as possible. If we can reach zero emissions, further global warming will stop within years, and the sooner this happens the smaller the risk of passing devastating tipping points. It would also minimize many other losses, damages, and human suffering from “regular” global warming impacts (e.g., heatwaves, floods, droughts, harvest failures, wildfires, sea level rise), which are already happening all around us even without the passing of major climate tipping points. I think they are right and still feel the urge to pretend it’s not happening or not affecting us so much so I can go on with life. This is probably the main problem. When we will finally feel enough pressure that it hurts so bad that we cannot ignore it anymore, it might be too late. Those tipping point frighten me even more than the gradual warming.

ndsipa_pomu 3y ago
It's quite scary that a lot of people don't take the risks of climate change seriously and instead wring their hands about the disruption that the phasing out of oil will cause. That's nothing compared to the disruption, famine, deaths and wars that will result from climate changes - just imagine a world where North America is in severe drought and most of Europe becomes unable to grow food or to live in without air conditioning.
- jfengel 3y ago
  They're convinced it's a hoax. They don't have to worry about trade offs. Burning more fossil fuels is all upside and no downside. We can publish all the articles we want on the magnitude of the problem. As far as they're concerned it's all evidence of the conspiracy.

jnxx 3y ago

I am aware that reports on the topic have been submitted before. This is a fantastic, well-written article by world-class climate scientist Stefan Rahmstorf.