We are approaching the tipping point': Marker for the collapse of key Atlantic current discovered

I am still waiting for a global climate model to be able to backcast the ice age history as found in geological evidences.

Articles like this one seem to say that the "tipping point" is heading towards massive cooling of the northern hemisphere. Which sounds a lot like the beginning of an ice age, not the global climate "melt-down" of insufferably high temperatures everywhere that are the angst of "global warming" activists.

Another disparity in this particular article is "sediment records over the past 100,000 years suggest that, at times, the AMOC has shut down abruptly, leading to major climate shifts over mere decades." But the last 100,000 years was the last "ice age", at least up to about 20,000 years ago. So, if this happens during ice ages, is it really a "global warming" issue? And, if it has happened before, why is it something that we can "prevent" by changing our emissions?

For some time, there has been a "snow blitz" theory for the beginning of ice ages that has enhanced snowfalls in the northern latitudes change the albedo sufficiently to initiate a new ice age by reflecting much of the summer insolation back into space, keeping the northern summers very cold. The theory originally was counting on the Arctic Ocean to become ice-free, so that it could provide moisture for the massive snow production. Since the Arctic ice does seem to be melting away, combining that with the cooling due to the Atlantic Meridional Overturning Circulation stopping would seem to be a good reason to suspect the onset of a new ice age. Is that what has been happening repeatedly over the last few million years? Will more CO2 in the atmosphere change this cycle - and if so, in what ways?

Humans will suffer no matter how the climate and sea level and rainfall patterns change, because we have so much expensive infrastructure built around the existing conditions, and such a high global population that there is no room to just move to a better place when one place becomes less hospitable while others become more hospitable.

But, my expectation is that we will see some pretty massive changes, no matter what we do. Even without contributions from human activities, sea levels have reached higher values in the previous interglacial periods - 25 feet higher than today about 120,000 years ago, and even higher in prior interglacial periods. We need to expect sea level to rise, and rise a lot. The only question is how fast, and how high. And, I have read that the Gulf Stream stopping would raise sea level by about 5 feet where I live, which would make my own home flood on every high tide. This article seems to say that could happen fast enough that a lot of people on the east coast of the U.S. could be flooded out in the next decade.
 

Atlan0001

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I am still waiting for a global climate model to be able to backcast the ice age history as found in geological evidences.

Articles like this one seem to say that the "tipping point" is heading towards massive cooling of the northern hemisphere. Which sounds a lot like the beginning of an ice age, not the global climate "melt-down" of insufferably high temperatures everywhere that are the angst of "global warming" activists.

Another disparity in this particular article is "sediment records over the past 100,000 years suggest that, at times, the AMOC has shut down abruptly, leading to major climate shifts over mere decades." But the last 100,000 years was the last "ice age", at least up to about 20,000 years ago. So, if this happens during ice ages, is it really a "global warming" issue? And, if it has happened before, why is it something that we can "prevent" by changing our emissions?

For some time, there has been a "snow blitz" theory for the beginning of ice ages that has enhanced snowfalls in the northern latitudes change the albedo sufficiently to initiate a new ice age by reflecting much of the summer insolation back into space, keeping the northern summers very cold. The theory originally was counting on the Arctic Ocean to become ice-free, so that it could provide moisture for the massive snow production. Since the Arctic ice does seem to be melting away, combining that with the cooling due to the Atlantic Meridional Overturning Circulation stopping would seem to be a good reason to suspect the onset of a new ice age. Is that what has been happening repeatedly over the last few million years? Will more CO2 in the atmosphere change this cycle - and if so, in what ways?

Humans will suffer no matter how the climate and sea level and rainfall patterns change, because we have so much expensive infrastructure built around the existing conditions, and such a high global population that there is no room to just move to a better place when one place becomes less hospitable while others become more hospitable.

But, my expectation is that we will see some pretty massive changes, no matter what we do. Even without contributions from human activities, sea levels have reached higher values in the previous interglacial periods - 25 feet higher than today about 120,000 years ago, and even higher in prior interglacial periods. We need to expect sea level to rise, and rise a lot. The only question is how fast, and how high. And, I have read that the Gulf Stream stopping would raise sea level by about 5 feet where I live, which would make my own home flood on every high tide. This article seems to say that could happen fast enough that a lot of people on the east coast of the U.S. could be flooded out in the next decade.
It isn't going to rise in salt sea water but in freshening salt freeing fresh waters which will turn to ice masses quickly unlike the salt seas. It is the more salt free -- though not salt free as such -- freshening waters that will block up the warm Atlantic current and roll pretty fast into the next fresh water 'Ice Age'. The almost cosmic 'colding' of the Earth over millions of years has become the norm of Earth with only lucky interludes of global warming due to our salt seas and, to some degree, tectonic plate movements. The salty oceans only turning slowly back to salty oceans melting the blockage of the Atlantic current flow enough to re-begin global warming. And there are other things, other possibilities including cosmic possibilities from outside Earth, for life on Earth to worry about during the 80,000 to 120,000 years of a real 'Ice Age' (not a 500 year long 'Little (half an...) Ice Age').
 
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The "Global Warming" term was initiated before we knew as much earth science as we know now (and there is still so much to learn as this article suggests. So let's avoid fifty years of pedantry and just say "Climate Chaos".
Not knowing when an AMOC event in the massively complex, interlocking system we call Earth is going to occur does not equate to it's not going to happen. It is evident 25 times in the Greenland ice cores that span around 800 thousand years.
So it will happen at some point, whether it's before or after we've managed or failed to reduce carbon and related atmospheric emissions.
 
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My thought is like the 'little ice age' Europe may get a slight reprieve for the earlier stages of global warming. Over the long run (if we don't enact major counter measures) is Europe will cook, broil, steam along with the rest of the planet.

I don't know if human caused GW is sufficient to cause a bio-terminal (ala Venus) feedback loop,
But is scarier than mere human extinction.
 
If Europe gets anything like the beginning of an ice age, it will really complicate the politics of conversion from fossil fuels to renewable energy sources.

Unless the climate forecasters are able to predict the onset and subsequent progression of the temperature declines, there will be no confidence left in the climate projections for any later warming.

As I stated in a previous post, the article's statement that the current has stopped multiple times during the last ice age tends to make it seem that it is not going to change the long-term trend. But, climate is probably mathematically "chaotic" in the same way that short term weather is chaotic, so it may take a coincident combination of various climate-affecting parameters to "flip" from overall warming to overall cooling and vice versa. Just looking at the Milankovitch cycles would suggest that ice ages should come and go on a frequency of twenty-something thousand years, not 100,000 years or 50,000 years, as the geological evidence indicates that they have after and before about 900,000 years ago.

I hope the climate modelers can get a reasonably accurate handle on what really causes ice ages to come and go, so that they will be able to retain some credibility when some of that chaotic behavior manifests itself in the present.
 

Atlan0001

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The "Little Ice Age" struck fast . . . within less than a century! Geologists have found that some of the largest, longest, Ice Ages encompassed large sections of the Earth within just two short centuries of their beginning . . . and lasted better than a hundred thousand, to a hundred and twenty thousand, and more years apiece before interludes of a few tens of thousands of years of global warming. We are [slightly] overdue for the start of the next one . . . Earth normal condition now (Ice Age), short the short interlude periods of global warming.
 
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