From about 80,000 to 20,000 years ago, Greenland temperatures abruptly warmed by about 10°C in just a few decades on at least 20 occasions. And then, about 870 to 1,500 years later, CO2 rose.
Li and Born (2019) document 8-16°C climate warmings (Dansgaard-Oeschger events) in Greenland that extended to both hemispheres between about 80 and 20 thousand years ago. (Though global in scope, temperature changes were less pronounced outside Greenland.)
These abrupt warmings occurred within decades (or less). It has been suggested the warm-ups may have required no external forcing, as they’re considered an “unforced oscillation”.
Image Source: Li and Born (2019)
A new study (Shin et al., 2020) suggests the about 1,000 years after these warming events occurred, CO2 concentrations rose.
Despite the millennial-scale duration of this lag relative to the decadal-scale temperature changes, there are many who believe CO2 changes are a driver of warming.
“However, the CO2 decrease did not always start at exactly the same time as the onset of the DO warming, and the lag itself varied. For example, during Marine Isotope Stage (MIS) 3, atmospheric CO2 maxima lagged behind abrupt temperature change in Greenland by 870±90 yrs. During MIS 5, the lag of atmospheric CO2 maxima with respect to abrupt temperature warming in the NH was only about 250±190 yrs (Bereiter et al., 2012). … During MIS 6d which corresponds to CDM 6d.1 and 6d.2, CO2 concentrations show a much slower increase over a duration of ~3.3 kyr. Here, CO2 lags behind the onset of the NH abrupt warming by 1,500±280 yrs and 1,300±450 yrs, respectively (1,400± 375 yrs on average).”
The hypothesis that some mysterious unknown forcing thing….
Which these guys call ‘internal variability’ causes abrupt cyclic abrupt warming and gradually cooling is, incorrect.
The alternative hypothesis is there a real physical explanation, a missing large ‘forcing thing’ that cyclically changes things on the earth.
If you look at the temperature data there is gradual cooling and then suddenly abrupt cooling.
What cause the abrupt cooling?
There needs to be a physical explanation for the super cooling events, such as the Younger Dryas abrupt cooling event that occurred 12,900 years ago.
The large forcing events have the power to force the terminate of interglacial warm periods. The interglacial warm periods, in the paleo record, are all less than 10,000 years in length, at which time there is abrupt cooling.
The Younger Dryas abrupt cooling event occurred when the summer insolation at 65N was maximum. Internal variability did not cause the earth, 12,900 years ago to go from interglacial warm to glacial cold with 70% of the cooling, occurring in less than a decade.
The earth stayed cold after the YD abrupt cooling event and then abruptly warmed to interglacial warm.
The temperature guys know zero and care zero about the geomagnetic data.
The last 800 years of the geomagnetic field record has been analyzed in detail, by the analysis of fired bricks, that were installed in Chalets in France and Italy.
The rich in the past had Chalets in Italy and France which they installed fancy ceramic tiles in. The fired brick retains the geomagnetic field intensity at the time of firing and the field orientation. The bricks have the date they were fired and a stamp of the manufacturer on them.
There is a Nova program that talks about the current, unexplained abrupt changes to the geomagnetic field orientation and strength.
That same Nova program, had a film segment showing the scientists analyzing the fired bricks and discussing the abrupt, large, unexplained changes they found in the geomagnetic field data from the last 800 years.
What was found by other scientists who analyzed the fired brick data geomagnetic field data and the timing of abrupt field changes, is the geomagnetic field is changing abruptly in strength and orientation, correlating with temperature changes during the 800-year period. This was completely unexpected and there is no explanation as to what is forcing the geomagnetic field.
The pattern is abrupt cooling (or no cooling if the forcing event occurs when the mechanism that causes cooling is saturated. Svensmark’s mechanism saturates such that there is no change in cloud cover, so another abrupt change in the geomagnetic field strength does not cause further cooling)…
followed by a steady cold period (just like the YD which was abrupt cooling, 1200 years of cold, and then abrupt warming) and then abrupt warming when there is the recovery of what was forced.
The temperature guys are only looking at temperature. The temperature changes are highly periodic and they correlate with geomagnetic field changes.
T
William
You are going to have to educate yourself about chaotic-nonlinear dynamics and face the fact that complex systems have internal dynamics that generate spontaneous fluctuations. Fight against it all you like, but that is the world that we live in. The ocean is not a passive puddle, responding only to external forcing. It is big and chaotic enough to force itself. And a lot else with it. No need for CO2. No need for the sun or magnetism or volcanoes or cow 🐄 farts. Climate changes itself. Some external forcing does occur of course notably Milankovitch forcing. But internal dynamics generate fluctuations on scales up to century and millennial, internally and spontaneously, without having to phone a friend.
This is hard to hear I know, but understanding this will give a significant step forward in appreciating how the world works.
In reply to:
The Ocean/Atmosphere/Ice/Snow Self-forcing Hypothesis
“The ocean is not a passive puddle, responding only to external forcing. It is big and chaotic enough to force itself. And a lot else with it. No need for CO2. No need for the sun or magnetism or volcanoes or cow farts. Climate changes itself.”
The observations do not support the butterfly hypothesis, the chaos does stuff hypothesis, my model is so complicated it can do anything ‘hypothesis’.
Observations support the assertion that the planet highly resists internal forcing events such as large volcanic eruptions. (Negative feedback).
An observational example that supports that assertion is, the Tambora eruption in 1816 caused a year without summer, not decades of widely oscillating temperatures.
If the planet highly resists forcing changes then there must be large and super large forcing mechanism.
The fact that the climate changes in the paleo record, are tightly periodic, rules out internal forcing along with there being no evidence that internal forcing is physical possible.
For example, that last 23 large and super large climate/change events (warming and cooling) have been shown to have a periodicity of 1500 years, maintaining that periodicity for 23 cycles….
The fact that climate change events are highly periodicity and that same periodicity is observed in both the interglacial period as in the glacial period…
… is strong observational evidence to support the assertion that the forcing event is not internal as internal forcing response and mechanisms would be different between the two periods because of the continental ice sheets.
The high periodicity of the events and the same periodicity for glacial/interglacial period, points to a forcing origin outside of the earth system.
The Sun theory … is that the sun changes in some way to cause multiple changes on the earth which are correlated, including temperature.
Supporting the sun theory…
… Is the fact that there are cosmogenic isotope changes when the temperature changes.
We know that at the time of the YD abrupt climate change event there is the largest change in C14 in the last 10,000 years.
http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml
Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
Many paleoclimatic data reveal a approx. 1,500 year cyclicity of unknown origin.
A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland..
… reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent;
with 95% confidence the period is maintained to better than 12% over at least 23 cycles.
This highly precise clock points to an origin outside the Earth system; oscillatory modes within the Earth system can be expected to be far
It is of course possible that you are both partially right. I suspect that the Earth’s magnetic field will influence the climate, and the movement of iron in the Earth’s core is probably as chaotic as the climate.
As for the climate, if you look at the individual temperature records then there is definite evidence of scaling behaviour in them. See –
https://climatescienceinvestigations.blogspot.com/2020/07/17-noise-fractals-and-scaling-revisited.html
Scaling is indicative of chaos and fractal geometry. It also allows us to extrapolate to longer timescales and estimate the size of fluctuations over those longer timescales.
My analysis suggests individual temperature records may exhibit fractal behaviour with self-similarity and a fractal dimension of 0.25. I have only found one station so far that doesn’t behave this way – Amundsen-Scott at the South pole which is just white noise. Most of the longer records do though.
If true, this fractal nature has massive implications for the interpretation of temperature data. It means that most long-term temperature trends (i.e. more than 100 years) are just noise or spontaneous fluctuations, but with much longer characteristic timescales. It also implies that long-term temperature fluctuations of 1 °C or more are not only possible, but likely.
Nice information.
If I have gotten the right take-away from this post, Hans Oeschger should be wildly oscillating in his grave. My bold below.
From: https://en.wikipedia.org/wiki/Hans_Oeschger
Oeschger was a pioneer and leader in ice core research. In collaboration with his colleagues he was the first to measure the glacial-interglacial change of atmospheric CO2.
Hans Oeschger was deeply troubled by the potential of an increased greenhouse effect caused by the steady increase of atmospheric CO2.
He was a Lead Author of the First Assessment Report of the IPPC.
He died in 1998. Willi Dansgaard died in 2011.
A chronological summary of their views on AGW might be interesting.
https://reader.elsevier.com/reader/sd/pii/S0277379118305705?token=AFBB3B306C45FA0A2138E4FC6B12AC2C47991A7F918E8E80F85B6104D9C3BE5B8E01B09962F5E94E523A0F2652015383
on p.2, in section “A Primer…”
So much for David Appell’s “warmer = drier” nonsense.
This shows how powerful CO2 is. It can cause warming long before it exists.
I’m sorry but i cannot accept that measuring co² locked in bubble of ice can give an accurate data point of co² at at all. I just recall my MSc degree work when we examined tunnelling by molecules under pressure.
Yes co² is a large molecule, and yes that makes tunnelling more difficult if not slower but , really ? 20000, 30000, 40000 years under pressure ?
Professor Salby showed some time ago that CO2 changes with and lags temperature On All Time Scales.
https://youtu.be/HeCqcKYj9Oc?t=5m30s
An important post, thanks.
Oceanic internal dynamics are probably the single most important climatic factor driving natural changes on multi-year timescales.
The Dansgaard-Oeschger oscillations are a perfect illustration and subject of study for how the oceans drive climatic changes, which in the case of the DO events are incredibly rapid, almost “violent”, temperature swings of 10 or more degrees C in a century or two.
That fact could almost be a starting point of climate study. Those that claim the current warming of one single degree C over 1-2 centuries is “unprecedented” are either plain lying or are pig 🐖 ignorant about climate history. The DO events were natural climate change 10x greater and faster than today.
If internal chaotic-nonlinear ocean dynamics (specifically the Gulf Stream salinity-Norwegian Sea downwelling feedback loop), can produce temperature excursions as violent as the DO events, then such dynamics have to be the “null hypothesis” for any climatic fluctuations such as recent warnings during 1910-1940 and 1970-2000, and cooling between 1940-1970.
And the sharply defined DO excursions are also very well suited to demonstrating that CO2 lags behind temperature in the time direction. Do it is not causative but is the result, of temperature change.
2 great papers, thanks!
William
The “butterfly wing” effect is a poor description of the role of chaotic processes in climate. And sheer complexity is not the issue either. It is in fact your arguments about intricate astrophysical forcing a that have the endless complexity that shields them from evidence based falsification.
“Chaos” is only a general title for a class of phenomena. Pure chaos is exhibited in fluid turbulence and is not in itself very important to climate. CO2 alarmists dismiss chaotic processes as mere noise and thus make the same error. But what is of interest in climate is where either internal feedbacks or external periodic forcing (such as solar) entrain a chaotic system to actually decrease its chaoticness (lower the dimensionality of the phase space) resulting in emergence of pattern. That’s where it starts to get interesting. The AMOC and ENSO are oceanic oscillations linked in this way to specific feedbacks, the North Atlantic salinity-downwelling feedback and the Bjerknes equatorial Pacific feedbacks respectively.
That’s how pattern can emerge from a chaotic system, with or without external forcing. And as Pierre’s featured paper (Li and Born 2019) shows, the scientific community are coming round to recognise phenomena like DO events as arising from intrinsic chaotic dynamics of the sort I described. And if such internal dynamics can cause the enormous DO climate excursions, they can cause any climate change.