Researchers find bottom of Pacific getting colder, possibly due to Little Ice Age

January 4, 2019 by Bob Yirka, Phys.org report
Cold waters that sank in polar regions hundreds of years ago during the Little Ice Age are still impacting deep Pacific Ocean temperature trends. While the deep Pacific temperature trends are small, they represent a large amount of energy in the Earth system. Credit: : Larry Madin, Woods Hole Oceanographic Institution

A pair of researchers, one with the Woods Hole Oceanographic Institution, the other Harvard University, has found evidence of deep ocean cooling that is likely due to the Little Ice Age. In their paper published in the journal Science, Jake Gebbie and Peter Huybers describe their study of Pacific Ocean temperatures over the past 150 years and what they found.

Prior research has suggested that it takes a very long time for water in the Pacific Ocean to circulate down to its lowest depths. This is because it is replenished only from the south, which means it takes a very long time for water on the surface to make its way to the bottom—perhaps as long as several hundred years. That is what Gebbie and Huber found back in 2012. That got them to thinking that at the bottom of the Pacific could offer a hint of what surface temperatures were like hundreds of years ago. To find out if that truly was the case, the researchers obtained data from an international consortium called the Argo Program—a group of people who together have been taking measurements down to depths of approximately two kilometers. As a comparative reference, the researchers also obtained data gathered by the crew of the HMS Challenger—they had taken Pacific Ocean temperatures down to a depth of two kilometers during the years 1872 to 1876. The researchers used the data from both projects to build a meant to mimic the circulation of in the Pacific Ocean over the past century and a half.

The model showed that the Pacific Ocean cooled over the course of the 20th century at depths of 1.8 to 2.6 kilometers. The amount is still not precise, but the researchers suggest it is most likely between 0.02 and 0.08° C. That cooling, the researchers suggest, is likely due to the Little Ice Age, which ran from approximately 1300 until approximately 1870. Prior to that, there was a time known as the Medieval Warm Period, which had caused the deep waters of the Pacific to warm just prior to the cooling it is now experiencing.

The HMS Challenger, a three-masted wooden sailing ship originally designed as a British warship, was used for the first modern scientific expedition to explore the world's ocean and seafloor. Gebbie and Huybers compared the cooling trend found in the model to ocean temperature measurements taken by scientists aboard the HMS Challenger in the 1870s and modern observations from the World Ocean Circulation Experiment of the 1990s. Credit: Painting of the HMS Challenger by William Frederick Mitchell originally published for the Royal Navy.

Explore further: Getting a longer heads-up on El Nino

More information: G. Gebbie et al. The Little Ice Age and 20th-century deep Pacific cooling, Science (2019). DOI: 10.1126/science.aar8413

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adam_russell_9615
2.1 / 5 (14) Jan 04, 2019
If the depths are getting colder where is that cold water coming from? Sure it could have originated from hundreds of years ago, but if it is getting colder then cold water has to be coming from somewhere here and now.
Surveillance_Egg_Unit
2.3 / 5 (9) Jan 05, 2019
green onions and the rest of the warmers will be along soon to answer the question.
zz5555
5 / 5 (11) Jan 05, 2019
Sure it could have originated from hundreds of years ago, but if it is getting colder then cold water has to be coming from somewhere here and now.

The waters on the bottom of the ocean take a long time to replenish - on the order of centuries. This is due to the Conveyor Belt that runs through all the oceans (https://www.natio...or-belt/ ). My understanding is that the surface water sinks in the northern Atlantic, near Greenland, and moves around the world from there. The deep water in the Pacific comes from there and it takes hundreds of years to replenish - it's a very slow process. So the water that is now replenishing the Pacific was last on the surface hundreds of years ago. You can click on the doi link in the above article to see the full paper.
zz5555
5 / 5 (9) Jan 05, 2019
There are also a couple references in the paper that might be of interest: https://journals....PO2699.1 and https://journals....11-043.1 . The latter paper uses radiocarbon dating to measure how long since ocean water in various basins has been on the surface (and mixed with the atmosphere).
Shootist
2 / 5 (4) Jan 05, 2019
Sure it could have originated from hundreds of years ago, but if it is getting colder then cold water has to be coming from somewhere here and now.

The waters on the bottom of the ocean take a long time to replenish - on the order of centuries. This is due to the Conveyor Belt that runs through all the oceans (https://www.natio...or-belt/ ). My understanding is that the surface water sinks in the northern Atlantic, near Greenland, and moves around the world from there. The deep water in the Pacific comes from there and it takes hundreds of years to replenish - it's a very slow process. So the water that is now replenishing the Pacific was last on the surface hundreds of years ago. You can click on the doi link in the above article to see the full paper.


It takes about 500 years for the conveyor current to turn over the ocean's waters and make one complete trip around the Earth. The little ice age started 800 years ago.
zz5555
5 / 5 (8) Jan 05, 2019
Apparently I should have mentioned that the National Geographic link is to a pop-sci article, included to get an idea of why the process is so slow, so some of the data in that article may not be accurate. That's why I included the links to the peer reviewed papers, one of which actually measured the age of the water. In fact, if you had looked at any of the other papers, you'd have seen that it's been 800 - 1400 years since the deep water in the Pacific has been in contact with the atmosphere. Again, this is a measured value which strongly suggests an error in the National Geographic article.
gh77
5 / 5 (6) Jan 05, 2019
Regarding : It takes about 500 years for the conveyor current to turn over the ocean's waters and make one complete trip around the Earth. The little ice age started 800 years ago"

Yes, the little ice age started 800 years ago AND lasted for 500 years. It would be interesting to get temperature readings all along the end of the conveyor to, if the premise is correct, replicate the temperatures during the period.
Benni
1.9 / 5 (9) Jan 05, 2019
If the depths are getting colder where is that cold water coming from? Sure it could have originated from hundreds of years ago, but if it is getting colder then cold water has to be coming from somewhere here and now.


This is a logical question, you should not have asked it, you are no longer a friend of the settled science crowd living here.
zz5555
5 / 5 (8) Jan 05, 2019
It would be interesting to get temperature readings all along the end of the conveyor to, if the premise is correct, replicate the temperatures during the period.

I recommend clicking on the DOI link in the article above - the paper is open access. I believe Fig. 2 is what you're looking for. The deep water in the Atlantic is only 100 - 400 years old, being closer to Greenland and all, so the waters there are showing warming.
rrwillsj
3.7 / 5 (9) Jan 05, 2019
a_r_9, you asked
"... If the depths are getting colder where is that cold water coming from? ..."

The "cold water" does not come from anywhere. The ocean depth's become colder as the heat dissipates. Check out how useful ocean thermal layers gave been for submarines sneaking around down there.

This brings up the misuse of the word "cold". Unfortunately that word is endemic from elementary education to fairytales & religion-based superstitions.

Actually there is no such thing as "cold". There is energy, there can be a lack of energy. Fahrenheit & Centigrade are crude tools to measure with.

Other factors to consider are inertia & conductivity. Inertia is why it takes so long to acheive anything. & while brine is a good conductor, that works both ways. To concentrate heat energy s& to dissipate it,

Remember those thermal layers? Visualize those as rivers above rivers. Sometimes they mix & sometimes they don't.
Anonym518498
1.4 / 5 (8) Jan 05, 2019
this is absolutely unacceptable, everybody knows it's warmer, ask scientific authorities like pelosi, clinton and algore, the people that reported this info must be sent to the gulag
Elmo_McGillicutty
1 / 5 (9) Jan 05, 2019
The water that saturates the planet is very hot and under great pressure. Not very far down, the earth starts warm and goes hot, all over. But the surface puddles are the coolest possible water. Evaporation perhaps. Something is cooling those puddles.

Jayarava
1 / 5 (7) Jan 06, 2019
When I see a figure like 0.02 °C I always think... "What is the margin of error?" Especially wrt those 19th Century measurements: if they were managing precision of better than ± 0.1 °C I'd be very surprised. We don't find out because they only present aggregated and averaged data.

As I read the article they claim that the inherent error in the modern and historical readings was about the same. Really? Measurement of temperature hasn't improved since 1870 when they lowered thermometers on hemp ropes? So error in the temp and depth!

In short, I doubt very much that this attempt at data manipulation and modelling means anything at all once you roll back all the assumptions and add up the margins of error.
greenonions1
4.1 / 5 (9) Jan 06, 2019
SEU
green onions and the rest of the warmers will be along soon to answer the question
What's a warmer? Am I also a gravityer - cuz I read a science text book that talked about gravity - and I did not freak out about a conspiracy to take all my money - and take over the world?
You really are scared of science aren't you egg.
rrwillsj
5 / 5 (3) Jan 06, 2019
Oh, go1, you are boiling an egg. & that little toad is too stupid to jump out of the pot!
As for the denierbots & woobots, benni, seu, annoyingmousie? Those are hust crudely coded puppets. By malicious programmers intent on disrupting public discourse.

E_McG, consider this POV.
The Earth's Ocean surface is a radiator, about a hundred million sq miles in area.
In daylight, some of our Sun's energy bounces off the surface of the Ocean's into the atmosphere.
Some of the energy is absorbed by the surface waters.
Some energy even escapes back out into Space.

Jay, I think I can agree with your comment? Do not accept pop-science articles as anything more than access ti the original research papers. Those links are at the bottom pf the article.

You bring up a good point about how the research is conducted & the level of tech used.

What device would you recommend to be used to measure Ocean Energy levels?
cantdrive85
1 / 5 (4) Jan 06, 2019
Was this not supposed to be where the missing heat from the recent AGW pause went? But now it's cooling from 800yrs ago? Typical non-science blather coming from the AGWites.
zz5555
5 / 5 (6) Jan 06, 2019
When I see a question like "What is the margin of error?" I always think "Why didn't they look at the paper, where the question is answered (see Fig. 3)?" Seriously, if you want to criticize the write up in this article, feel free - they're not generally written by the scientists so often contain errors (although margin of error probably isn't something you'd find in an article at this level).

As I read the article they claim that the inherent error in the modern and historical readings was about the same.


I can't find this claim in the article - can you point it out? It's obviously not in the paper since the paper goes into detail about what they had to do to remove the inherent errors in the historical readings. Again, it's probably best to read the paper.
zz5555
5 / 5 (7) Jan 06, 2019
In short, I doubt very much that this attempt at data manipulation and modelling means anything at all once you roll back all the assumptions and add up the margins of error.

Since you couldn't be bothered to read the paper, I doubt very much that your opinion on it is relevant.

Seriously, this isn't a very controversial topic. It takes two very well known facts (1:it takes hundreds of years for surface water to reach the deep ocean and 2:the surface temperature was colder during the little ice age) and puts them together to reach a logical conclusion (the deep Pacific water is just now cooling due to the little ice age). It in no way threatens your political views of global warming/climate change and doesn't involve dark matter/energy or relativity so I'm not sure why the anti-science brigade has jumped on it.
antigoracle
1.8 / 5 (5) Jan 06, 2019
Prior to that, there was a time known as the Medieval Warm Period, which had caused the deep waters of the Pacific to warm just prior to the cooling it is now experiencing.

I guess these guys did not get the memo. According to AGW Cult lore...er..excuse me...pathological LIES, the MWP never existed.
greenonions1
5 / 5 (6) Jan 06, 2019
zz
I'm not sure why the anti-science brigade has jumped on it
I think the answer to that - is that a very superficial take on this article - might lead someone to say "ha ha - see the ocean is really cooling - and the 'warmists' were wrong all along!!!" As is often the case - confusing one piece of a highly complex - multi dimensional puzzle - with the whole picture. Hey - it snowed in Oklahoma on Thursday - must be globull cooling - right?
greenonions1
5 / 5 (6) Jan 06, 2019
According to AGW Cult lore...er..excuse me...pathological LIES, the MWP never existed
Yep - we only know about the MWP cuz goracle got in a time machine and went back to take temperature readings. Oh no - that's wrong - we actually know about it cuz of science. Like hard working researchers - doing ice cores/tree ring analysis/sediment analysis etc. etc. etc. So the MWP has been written about extensively - and of course only a trained monkey would suggest that scientists assert "the MWP never existed."

www.pages-igbp.or...-it-warm
cantdrive85
1 / 5 (4) Jan 06, 2019
For a good laugh, read the following;

'Evidence Shows Global Heat May Be Hiding in Oceans'
http://www.climat...ns-16783

They also mention in the article the dearth of real data regarding deep ocean measurements.
zz5555
5 / 5 (7) Jan 06, 2019

For a good laugh, read the following;

'Evidence Shows Global Heat May Be Hiding in Oceans'
http://www.climat...ns-16783

That's a discussion on ocean warming between 500-1000m deep. The study concerned by the above article is for 1800-2600m deep. There is a vast difference in how the two regions are affected by surface temperatures. Unfortunately, different people mean different things by "deep ocean".

They also mention in the article the dearth of real data regarding deep ocean measurements.

That's based on a 6 year old study. Things are much better now (though not perfect). Regardless, there was no "dearth of real data" for the above study.

Incidentally, here's another study looking at ARGO data that comes to the same conclusion: the deep Pacific is currently cooling (https://journals....6-0396.1 ).
Sahstar
5 / 5 (2) Jan 06, 2019
If the depths are getting colder where is that cold water coming from? Sure it could have originated from hundreds of years ago, but if it is getting colder then cold water has to be coming from somewhere here and now.

The article is a bit unclear (that "replenished only from the South" sounded as a description rather than an explanation), but apparently this is colder water from the "Little Ice Age", i.e. water that was cooled / shed some heat until ~1870.
The title "getting colder" also appears to be wrong, since this is just water a bit colder than expected, and it is not *still* getting colder (at least not from the Little Ice Ace). It was rather getting colder "over the course of the 20th century", as it mentions in the end.
cantdrive85
1 / 5 (4) Jan 06, 2019
That's based on a 6 year old study. Things are much better now

Ooh, really? Did Indiana Jones locate a treasure trove of historical (really) deep temp data? Or are you suggesting such a small dataset is relevant in the discussion of climate?
antigoracle
1 / 5 (4) Jan 06, 2019
The raw ARGO data confirmed oceanic cooling even in the upper layer, but to sustain the pathological lies of their dogma, the AGW Cult cooked the data to show warming. To further conceal their deception they have refused to release the raw data to anyone but a few of their trusted cult members. That's AGW Cult PATHOLOGICAL "science".
RealityCheck
2 / 5 (4) Jan 06, 2019
It's the trend itself (during the 20th century) that matters to us NOW, regardless of whether it's by a smaller or larger amount/rate.

And while this initial/current deep-ocean-cooling period may have started due to Little Ice Age, it is NOW being prolonged by cool water shed/chilled by the melting ice in Northern AND Southern hemispheres; due to AGW induced warming/melting of the global ice/coldwater 'reservoirs' previously retaining 'refrigeration mass', BUT NOW chilling/releasing cold water which is making its way into deep oceans at all levels....not only due to cooler waters 'sinking', but ALSO due to MORE VIOLENT MIXING by more extreme storms/currents etc caused by increased energy AGW is giving to surface waters/atmosphere TURBULENCE/STREAMING/VORTICES etc all over the globe (which is becoming increasingly self-evident/costly to global populations by the day now).

So arguing over historical trifles is FUTILE while REALITY NOW is self-evident under everyone's noses.
granville583762
5 / 5 (1) Jan 07, 2019
7miles deep the heat is on

Have we not seen David Attenborough on the Marianas Trench
he has shown ocean sea life 7miles deep on the ocean floor
lit up by these deep sea submersibles
where all the sea life falls on the ocean floor where blind sharks, eels and crabs make a living
it is irrelevant what the temperature is 7miles deep
firstly 2km is 1¼miles
so
there is no contest
if a realistic temperature of the sea floor is to be established
these deep sea submersibles
are measuring the temperatures
7miles deep
granville583762
5 / 5 (1) Jan 07, 2019
Temperature is Quasi Neutral

As the ice sheets melt
as they carve out huge tonnage of ice
as they slide into the icy Atlantic waters
as they melt
the falling cold water
brings relatively fresh water
from the warmer depths
and
with this rising water
brings millions of krill
millions of sea life
hiding
in the warmer waters of the depths
because
in the arctic
the sea is rich in life
the point is
the sea at great depths
is warmer than we think
it is a huge heat sink
heated below
by volcanic activity as the earth cools
and
heated above by our fusion reactor
92million miles in space
as the earth rotates this great mass of water inducing currants
with its temperature gradient of the polar caps
and the heat of the equator

As JD used to say, Quasi Neutral
the total temperature of the sea
is
Quasi Neutral
the overall temperature
of the sea is what counts
not these swirling eddy currents
In these changing seasons of this earth
rrwillsj
5 / 5 (2) Jan 07, 2019
granny, it is my opinion (only an opinion) that you are mistaken to use the word "temperature". It is too imprecise & obfuscate.

For instance, that water you measured a minute ago? Has traveled a hundred meters laterally & twenty meters vertically. With the result that the temperature of the original water you measured has risen or fallen by ten degrees or both or nore or less or not.
& it will continuously change to your frustration.

Instead, you need to measure energy levels. Still not perfect but more accurate than temperature. In other words. there are a whole lot of random variations occurring that can only be measured as probabilities.
granville583762
3 / 5 (2) Jan 07, 2019
Imprecise science
rrwillsj> granny, it is my opinion (only an opinion) that you are mistaken to use the word "temperature". It is too imprecise & obfuscate.

For instance, that water you measured a minute ago? Has traveled a hundred meters laterally & twenty meters vertically. With the result that the temperature of the original water you measured has risen or fallen by ten degrees or both or nore or less or not.
& it will continuously change to your frustration.

Instead, you need to measure energy levels. Still not perfect but more accurate than temperature. In other words. there are a whole lot of random variations occurring that can only be measured as probabilities.

On the Atlantic sea floor the water is very still
but your right measuring sea temperature a is a fickle science
it rather negates the article a mite
You certainly can't measure to ½° with any accuracy
TheGhostofOtto1923
not rated yet Jan 10, 2019
Well at least the core isnt heating up... or is it?

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