Cold era, lasting from early 15th to mid-19th centuries, triggered by unusually warm conditionsPeer-Reviewed Publication
UNIVERSITY OF MASSACHUSETTS AMHERST
AMHERST, Mass. – New research from the University of Massachusetts Amherst provides a novel answer to one of the persistent questions in historical climatology, environmental history and the earth sciences: what caused the Little Ice Age? The answer, we now know, is a paradox: warming.
The Little Ice Age was one of the coldest periods of the past 10,000 years, a period of cooling that was particularly pronounced in the North Atlantic region. This cold spell, whose precise timeline scholars debate, but which seems to have set in around 600 years ago, was responsible for crop failures, famines and pandemics throughout Europe, resulting in misery and death for millions. To date, the mechanisms that led to this harsh climate state have remained inconclusive. However, a new paper published recently in Science Advances gives an up-to-date picture of the events that brought about the Little Ice Age. Surprisingly, the cooling appears to have been triggered by an unusually warm episode.
When lead author Francois Lapointe, postdoctoral researcher and lecturer in geosciences at UMass Amherst and Raymond Bradley, distinguished professor in geosciences at UMass Amherst began carefully examining their 3,000-year reconstruction of North Atlantic sea surface temperatures, results of which were published in the Proceedings of the National Academy of Sciences in 2020, they noticed something surprising: a sudden change from very warm conditions in the late 1300s to unprecedented cold conditions in the early 1400s, only 20 years later.
Using many detailed marine records, Lapointe and Bradley discovered that there was an abnormally strong northward transfer of warm water in the late 1300s which peaked around 1380. As a result, the waters south of Greenland and the Nordic Seas became much warmer than usual. “No one has recognized this before,” notes Lapointe.
Normally, there is always a transfer of warm water from the tropics to the arctic. It’s a well-known process called the Atlantic Meridional Overturning Circulation (AMOC), which is like a planetary conveyor belt. Typically, warm water from the tropics flows north along the coast of Northern Europe, and when it reaches higher latitudes and meets colder arctic waters, it loses heat and becomes denser, causing the water to sink at the bottom of the ocean. This deep-water formation then flows south along the coast of North America and continues on to circulate around the world.
But in the late 1300s, AMOC strengthened significantly, which meant that far more warm water than usual was moving north, which in turn cause rapid arctic ice loss. Over the course of a few decades in the late 1300s and 1400s, vast amounts of ice were flushed out into the North Atlantic, which not only cooled the North Atlantic waters, but also diluted their saltiness, ultimately causing AMOC to collapse. It is this collapse that then triggered a substantial cooling.
Fast-forward to our own time: between the 1960s and 1980s, we have also seen a rapid strengthening of AMOC, which has been linked with persistently high pressure in the atmosphere over Greenland. Lapointe and Bradley think the same atmospheric situation occurred just prior to the Little Ice Age—but what could have set off that persistent high-pressure event in the 1380s?
The answer, Lapointe discovered, is to be found in trees. Once the researchers compared their findings to a new record of solar activity revealed by radiocarbon isotopes preserved in tree rings, they discovered that unusually high solar activity was recorded in the late 1300s. Such solar activity tends to lead to high atmospheric pressure over Greenland.
At the same time, fewer volcanic eruptions were happening on earth, which means that there was less ash in the air. A “cleaner” atmosphere meant that the planet was more responsive to changes in solar output. “Hence the effect of high solar activity on the atmospheric circulation in the North-Atlantic was particularly strong,” said Lapointe.
Lapointe and Bradley have been wondering whether such an abrupt cooling event could happen again in our age of global climate change. They note that there is now much less arctic sea ice due to global warming, so an event like that in the early 1400s, involving sea ice transport, is unlikely. “However, we do have to keep an eye on the build-up of freshwater in the Beaufort Sea (north of Alaska) which has increased by 40% in the past two decades. Its export to the subpolar North Atlantic could have a strong impact on oceanic circulation”, said Lapointe. “Also, persistent periods of high pressure over Greenland in summer have been much more frequent over the past decade and are linked with record-breaking ice melt. Climate models do not capture these events reliably and so we may be underestimating future ice loss from the ice sheet, with more freshwater entering the North Atlantic, potentially leading to a weakening or collapse of the AMOC.” The authors conclude that there is an urgent need to address these uncertainties.
This research was supported by funding from the National Science Foundation.
JOURNAL
Science Advances
DOI
ARTICLE TITLE
Little Ice Age abruptly triggered by intrusion of Atlantic waters into the Nordic Seas
ARTICLE PUBLICATION DATE
15-Dec-2021
The climate cycles. Cold periods are almost always preceded by warmer periods. This is because a warmer period after a warm period is almost never called a cold period. A cold period could be called predictive of a following warm period due to regression to the mean. Climate has cycled long before the appearance of humanity. Climate gets warm, then cold, then warm again, then cool again. Always cycling.
Long term cycles may be measured in thousands of years. A human lifetime is but two data points in a graph of thousands of data points. A “sudden” change (notwithstanding the Sun emitting a super-sized flare) would take one or two thousand years to happen. Most change is gradual.
What a gyp!
I read this article, preparing for the BINGO! moment when manmade CO2 was found guilty, and to my profound disappointment, they blamed it all THE SUN!
(This will be a career-limiting moment for these “climate scientists”)
As is pointed out below, there are clear cycles that happen globally across the while 1Ma of the ice age, across the planet. Not a local thing.The evidence says that is so, in ice cores and also seen in equatorial coral records and glacier advance and retreat. I suggest observed reality trumps the guesses of these paper pushing “scientists”.
” But in the late 1300s, AMOC strengthened significantly, which meant that far more warm water than usual was moving north, which in turn cause rapid arctic ice loss.
Over the course of a few decades in the late 1300s and 1400s, vast amounts of ice were flushed out into the North Atlantic, which not only cooled the North Atlantic waters, but also diluted their saltiness, ultimately causing AMOC to collapse.
It is this collapse that then triggered a substantial cooling. ”
Yessah!
This is exactly what I read in 1999 from US oceanographers who warned us of a new edition of what not only happened at the beginning of the LIA but also at the beginning of the period called ‘Younger Dryas’, some thousands of years ago.
https://ocp.ldeo.columbia.edu/res/div/ocp/arch/examples.shtml
No kidding, they also want us to believe it was colder in the 1930 along with Mann’s hockey stick…disinformation indeed
Oh, for crying out loud, cooling is caused by warming. On credibility at all .
That should have read: no credibility at all.
I guess they expect cooling in the near term and are trying to justify that cooling with a BS excuse.
BINGO!
Someone explained to these “Scientists” (followers of Scientism, not followers of the Scientific Method) that their refrigerators cooled the food inside by extracting the heat and pushing it out the back, heating the kitchen. Being interested in a steady paycheck, these same “Scientists” extrapolated that explanation to the whole world.
Since warming is now established as the prime factor for global cooling, all attempts to cool the globe by restricting warming are doomed to failure.
You have to follow the science after all.
No no… Just send them more money and they will figure out something else that we need to restrict in order to save the world.
There’s not all that much ice in the arctic. If more of it is being “flushed” out, then there would be even less ice. How exactly did this extra flushing manage to continue for hundreds of years?
Beyond that, sea ice is formed from sea water, so when sea ice melts, you haven’t changed the total saltiness of sea water.
Actually, sea ice normally contains very little salt in it. The water freezes and the salt concentrates in a water layer underneath until it mixes with other water. You can melt the sea ice and drink the resulting water.
If you meant that the total amount of salt remains in the water before and after sea ice forms then you are correct, but the melting ice would form a less salty volume until mixing has occurred.
As people salting roads and driveways every year prove, salt only lowers the temperature where water freezes.
Some of the salt is excluded by crystallization of water, but below a certain temperature easily reached in the Arctic and salt water freezes.
Drink melted sea ice at your own risk.
Climate models do not capture these events reliably and so we may be underestimating future ice loss from the ice sheet.
Or could they be overestimating?
This is cutting edge science….for Amherst.
When I read anything that claims the LIA and MWP were Europe only I look here.
Climate reconstructions of the ‘Medieval Warm Period’ 1000-1200 AD.
https://www.google.com/maps/d/u/0/viewer?mid=1akI_yGSUlO_qEvrmrIYv9kHknq4&ll=-3.81666561775622e-14%2C118.89756200000005&z=1
O…K…so… If it warms and all ice melts raising sea levels by 200 feet, it’s the fault of CO2 – BUT if it suddenly turns cold and we all die of famine it’s the fault of CO2. Sounds like a really sound scientific prediction to me! (*cough*)
Or…Nature is chaotic and we cannot predict what the climate will be like in 30 years…That works too, is simpler, and doesn’t require anyone to reduce CO2. I like this one better.
Don’t we have recently published studies showing that this is not true?
So if you want to stop warming and stop cooling, you must do as you are told and submit to your new leftist masters. I can see thru the obvious ploy.
The LUNATICS are in charge.
What l think was the cause of the LIA is the effects that low solar activity has on the jet stream.
lts looks like when there is low solar activity. The smooth zonal flow of the jet stream begins to brake down and the flow of the jet stream becomes more scatted and messy right across the globe. lts this scattering of the jet stream that helps to stall the weather patterning across the globe and so increase the chances of blocking highs happening. The northern Atlantic and Greenland look phone to blocking during these times of low solar activity.
Look at the current flow of the jetstream. Looks like winter is about to descend into China fresh out of Siberia. … https://earth.nullschool.net/#current/wind/isobaric/500hPa/orthographic=-225.75,44.48,671/loc=-9.009,50.772
“New research from the University of Massachusetts Amherst”
Wow, my alma mater- where, I’ve been told, I spent the late ’60s- though, it’s true, if you remember the ’60s, you weren’t there.
When zI was taking Geology and oceanography years ago I had a professor who postulated this very scenario. So glad to know that others now postulate the same causation .
Sorry to be a skunk
But didn’t Mann recently “prove” these ocean cycles don’t exist, it’s all volcanos?
And that there was no warm period followed by the LIA?
Sarc/
Seek and Thou Shall Find.
Never so true as in climate “research”, especially if what you are looking for is something to counter hard cold (pun intended) facts that seem to disprove your narrative.
“past 10 years”?
I’ve always heard that it is impossible to capture recent varve without disturbing the layers preventing any accuracy about recent events.
A claim that seriously cripples their other claims.
Claims that they believe weather systems are in lockstep with water temperatures…
What marine records?!
Especially, marine records that recorded 1300-1500 water temperatures?
Were Vikings sticking their fingers in buckets of water? And how many times did they perform these actions?
If they can’t prove or verify the first part of their claim, the rest of the paragraph is ridiculous.
“This has had irreversible impacts“?
The conclusions reached in this research cause irreversible impacts to normal brains.
Another piece of “Confirmation Bias” where all facts discovered are immediately assumed to prove the researcher’s case. A case that assumes proof of frontal systems, high pressure systems and low pressure systems.
Global warming happens when you are living in a glaciation period and it warms quickly.
We aren’t in glaciation period, yet.
Our global climate is called an icehouse global climate.
Our age is called, Late Cenozoic Ice Age. It began about 34 million years ago, and in the last 2 million years, it got colder.
Climate science are the idiots of science.
They don’t know why in the coldest period of glaciation period; it can suddenly get a lot warmer. They know it’s not from CO2 levels.
In our present interglacial period, called the Holocene period, when it suddenly got warmer,
it’s called the Holocene Climate Optimum. Wiki:
“The Holocene Climate Optimum (HCO) was a warm period that occurred in roughly the interval roughly 9,000 to 5,000 years BP, with a thermal maximum around 8000 years BP. “
And got so warm, the Sahara Desert greened. Becoming mostly grassland and had forests and rivers and lakes which have disappeared. We have cooling for 5000 years.
All interglacial period have a thermal maximum {idiot climate scientists don’t know why} and we have past our peak, and predictable {because we are in an Ice Age} we enter a glaciation
period. Or if waiting for global warming, first everything gets frozen, then we get a thermal maximum, or should happen in tens of thousands of years.
“ unprecedented cold conditions in the early 1400s, only 20 years later.”
Unprecedented cold conditions? Isn’t it called the “Little” Ice Age because it was milder and much shorter than the ice age that ended 14,000 years ago?
After reading the article, I can only conclude that global warming is self-correcting. I guess the oceans aren’t going to boil after all.
The interest now is watching how the Climate Mafia will show that this medieval global warming was caused by the use of fossil fuels. They can’t allow natural variability to cause such events.
And when is this supposed to happen? The day after tomorrow I suppose.
I see what you did there…