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from the buffers-work-up-to-a-point-and-then-all-hell-breaks-loose dept.
If circulation of deep waters in the Atlantic stops or slows due to climate change, it could cause cooling in northern North America and Europe – a scenario that has occurred during past cold glacial periods.
Now, a Rutgers coauthored study suggests that short-term disruptions of deep ocean circulation [also] occurred during warm interglacial periods in the last 450,000 years, and may happen again.
Ironically, melting of the polar ice sheet in the Arctic region in a warmer world, resulting in more fresh water entering the ocean and altering circulation, might have caused previous coolings.
[...] The study, published in the journal Science and led by scientists at the University of Bergen in Norway, follows a 2014 study on the same topic.
"These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions," said coauthor Yair Rosenthal, a distinguished professor in the Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences at Rutgers University–New Brunswick. "Although the disruptions in circulation and possible coolings may be relatively short-lived – lasting maybe a century or more – the consequences might be large."
The warm North Atlantic Current -- the northernmost part of the Gulf Stream -- flows into the Greenland Sea. It becomes progressively colder and saltier due to heat loss to the air, eventually sinking and forming the North Atlantic Deep Water formation -- a mass of deep, cold water that flows southward. Melting of the polar ice sheet in the Arctic region would result in more fresh water entering the ocean and disrupting that circulation pattern, potentially causing cooling in northern areas of Europe and North America.
[...] The latest study covers three other warm interglacial periods within the past 450,000 years. During all of them, regardless of the degree of global warming, the scientists found similar century-long disruptions of the North Atlantic Deep Water formation. And they found that such disruptions are more easily achieved than once believed and took place in climate conditions similar to those we may soon face with global warming.
Journal Reference:
Eirik Vinje Galaasen, Ulysses S. Ninnemann, Augustin Kessler, et al. Interglacial instability of North Atlantic Deep Water ventilation. Science, 2020 DOI: 10.1126/science.aay6381
(Score: -1, Troll) by Anonymous Coward on Friday March 27 2020, @11:59PM (12 children)
Global warming, global cooling... just pick one thing to panic about and stick with it.
(Score: 4, Informative) by Azuma Hazuki on Saturday March 28 2020, @12:07AM (7 children)
I was waiting for some idiot to say this. First post? No surprise there. Let me break this down for you: *global warming and localized cooling can co-exist.* This is not difficult. Why is this so? Because the increased heat need not be spread uniformly. The overall energy balance--and therefore temperature--of the planet will still be higher.
These deep currents have been analogized to conveyor belts carrying parcels of heat, which is one of those lies-to-children that works well enough for our purposes. Shut them down, and the "heat parcels" just stay where they are, in the tropics. Which, by the way, could mean even frickin' *worse* hurricanes on top of everything else, given that those are a function of sea surface temperatures.
I am "that girl" your mother warned you about...
(Score: 0, Funny) by Anonymous Coward on Saturday March 28 2020, @12:29AM (2 children)
Yikes! Better get Chief Gordon to flash the Grump Signal so we can get St Greta working on this ASAP.
(Score: 3, Insightful) by Azuma Hazuki on Saturday March 28 2020, @12:31AM (1 child)
You aren't fit to breathe the same air as that girl.
I am "that girl" your mother warned you about...
(Score: 1, Funny) by Anonymous Coward on Saturday March 28 2020, @12:35AM
You're right - but we allow her to breathe it anyway, just because we are nice, tolerant people.
(Score: 2, Interesting) by Anonymous Coward on Saturday March 28 2020, @03:23AM (1 child)
Your comment is generally correct, but I think the effect on hurricanes is probably a bit more complicated.
All other things equal, increasing sea surface temperatures will result in stronger hurricanes. This is not in dispute. But there are other factors like vertical wind shear that affect hurricane formation and intensity. Vertical wind shear is the change in wind speed and direction as you go up in the atmosphere. Strong vertical wind shear is favorable for supercell thunderstorms and tornadoes, but is unfavorable for hurricanes.
One way we calculate vertical wind shear is to pick two different levels in the atmosphere. We start at the origin of a graph and draw two vectors outward, one for the winds at each of the levels. Then we draw a third vector connecting the heads of the first two vectors. That third vector is the shear vector. The length of that third vector is the amount of vertical wind shear. As that vector gets longer, there's more shear in the atmosphere. Winds in the upper atmosphere are usually quite a bit stronger than near the surface, so increasing the upper-level winds usually produces more vertical wind shear.
What you're describing is that you'll have warmer water near the equator and cooler water at high latitudes. There is some coupling between sea surface temperatures and the air above the surface. That means the lower atmosphere will probably be warmer in the tropics and a bit cooler at higher latitudes. In other words, you'll have a bigger temperature difference between the equator and, say, 40 degrees north. These temperature differences in the lower atmosphere cause differences in air pressure in the upper atmosphere. So if there's a bigger temperature gradient in the lower atmosphere, there will be a stronger pressure gradient in the upper atmosphere. And increasing the pressure gradient in the upper atmosphere will also result in stronger upper-level winds. And increasing the upper-level winds also probably means more vertical wind shear.
To summarize, sea surface temperatures will get warmer, but the vertical wind shear will probably get stronger. This article discusses the North Atlantic basin. And climate models generally predict that sea surface temperatures will increase in the tropical North Atlantic, but that vertical wind shear will also get stronger. One is favorable for stronger hurricanes, but the other is unfavorable.
Sea surface temperatures tend to vary on a seasonal time scale, with the warmest water in September and the coldest water in February and March. However, vertical wind shear tends to vary more on weather time scales, increasing and decreasing on the other of days instead of months. On average, there will probably be more vertical wind shear, which has the effect of suppressing hurricane activity. But because there's significant variability on weather time scales, there will be times during the season when the shear abates. When that happens, the very warm sea surface temperatures may more strong hurricanes. But the rest of the time, when the shear is stronger, it may suppress hurricane activity. One hypothesis is that we'll see an overall suppression of hurricane activity in the North Atlantic, but hurricanes that do develop will tend to be stronger. We may see fewer hurricanes, but the ones that occur will be more extreme.
This is an active area of research and we don't know for sure how global warming will actually affect hurricane activity in the North Atlantic. And it's also quite possible that some of the other tropical cyclone basins around the world won't behave in the same manner as the North Atlantic.
(Score: 2) by maxwell demon on Saturday March 28 2020, @07:30AM
Let me shorten that for you:
But apart from the wordiness, interesting comment.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Saturday March 28 2020, @04:23AM
You seem to spend a lot of time in the company of idiots. Birds of a feather flock together, right?
(Score: -1, Troll) by Anonymous Coward on Saturday March 28 2020, @11:32AM
The physical reality is more discerning.
(Score: 5, Informative) by Anonymous Coward on Saturday March 28 2020, @12:22AM (1 child)
Global average temperatures are increasing. The observations show this very clearly.
We know that the rate of temperature changes aren't the same everywhere. Observations clearly demonstrate that polar regions, especially the Arctic, are warming much faster than the rest of the planet. The observations clearly demonstrate that there isn't a single rate of global temperature increase, but that there are significant regional variations.
It is outright disingenuous to deny global warming on the basis that a few regions may experience cooling while the planet warms significantly overall. But you knew that already, just from looking at the observations.
Science denial is science denial, and it's dangerous. Whether we're talking about lifting social distancing guidelines before COVID-19 infections have peaked, claiming that vaccines cause autism despite significant evidence to the contrary, or denying that human activities are causing global warming, people who deny science are a menace to society and will harm all of us.
(Score: 0) by Anonymous Coward on Saturday March 28 2020, @02:25PM
>Science denial is science denial, and it's dangerous
Science denial cannot happen.
Case in point, study says circulation may affect cooling. Armed with this hypothesis scientists will formulate a prediction, true if hypothesis true and false otherwise. This will validate the theory.
We have time to wait for this to happen while we keep polluting? different question. A wrong question to ask because of the term "we", the shield of evil actors, but let's pretend otherwise. Ideally we shouldn't risk, but ideally we shouldn't have tolerated the industrial revolution as it happened, nor wars, nor fiat money, nor political actions by religions...
Sure, we must start to say no from one line in the sand.
OTOH the climate change line has been drawn by the elite who is elite by excelling in all other destruction, not by the hero scientist hollywood style character. This might be a trap, it surely has been till now but, cry wolf forever and you will be right eventually.
(Score: 0) by Anonymous Coward on Saturday March 28 2020, @01:15PM
Clickbait article-not because it is incorrect, but rather this is just another retelling of what has been known for decades.
It's like an a new article published that says "Geologists confirm the theory of plate tectonics" (known since the 60's) or "Physicists confirms Newton's laws of motion" (known for centuries). But I suppose for many it's new for you.
Even in the 80's oceanography (a real science) suspected (knew?) the gulf stream and other currents were not immutable and their current intensity exists as it is today simply due to our current global climate.
Anyways, climatology has become the astrology of the sciences. Climatologist predictions are so ambiguous they make fortune cookies, alchemists, or astrologers look exact.
They cover all the cases and possibilities with ambiguous predictions of "May warm, may cool, may rise, may increase rainfall, may decrease rainfall, may decrease food production, may increase food production, may flood, may dry up" so obviously when the regional climates do change 10, 50, 100 years from now they can say "Look at how we predicted it! Look at how right we were" and the public will eat it up.
Every time it's more of the same old, wishy-washy predictions from a wishy-washy poorly-predictable science that has fooled the public into thinking they can predict what will happen.
Remember that climatologists are so alarmed by their predictions that they sacrifice themselves by the thousands to fly to dozens of climate change conferences, all inclusive, all over the world every year in GHG spewing jets. Well they did up to the covid crisis, but once that is over I'm sure it will begin again. Free flights, free 5* hotels, smorgasbord of food cooked by world renowned chefs, $100 bottles of wine...just for saying "I predict the climate might warm or it might cool or it might stay the same."
What dedication!!
More like what a racket!
(Score: 2) by chewbacon on Saturday March 28 2020, @02:36PM
They decided to panic about COVID-19.