From NOT A LOT OF PEOPLE KNOW THAT
By Paul Homewood
I came across this paper again the other day. It’s from 2016, but still highly relevant:
https://www.sciencedirect.com/science/article/abs/pii/S0277379116300427
It’s quite a powerful study because of its wide geographical coverage, unlike other studies that focus on one particular proxy in one location.
Below is the key graph. It’s measured in SDs, but illustrates how temperatures plunged around 3000 years ago, and notably since the Middle Ages:
Figure 2 also shows the area of the Greenland ice sheet, which reached post ice age minimum about 4000 years ago, and was at a maximum at the end of the Little Ice Age:
The Holocene Optimum was about 7,000 years ago. The pyramid builders were about 5,500 years ago. Cleopatra VII (the one who played around with Julius Caesar, Mark Anthony, and was played by Elizabeth Taylor) is closer to us in time than she was to the pyramid builders. That’s how remote the pyramid builders were. 4,000 years ago for a minimum does not align with 7,000 years ago, and it doesn’t align with the pyramid builders either.
Climate is not global. Milankovitch forcing, the most powerful on the millennial scale, is hemispheric, seasonal, and by latitude. Different places have different profiles.
Yet around 5,200 years ago the globe experienced a profound cooling event known as the 5.2 kiloyear event. Afterward, the energy content of the planet started decreasing despite some regions still warming, particularly in the Southern Hemisphere. It is known as the Neoglaciation, which lasted until 1840. All over the world glaciers grew.
4000 years for a minimum in the Greenland ice sheet fits perfectly.
This is figure 77 from my forthcoming book:
It shows how the global temperature responds to northern summer insolation, while Southern Hemisphere temperatures and CO2 levels respond to southern summer insolation. Models are unable to reproduce the climate of the Holocene.
It also shows the 5.2 kyr event that was also prominent in Antarctica. The 5.2 kyr event is also prominent in global glacier growth, as shown in another book figure.
There appears to be no correlation between CO2 concentration and the temperature anomaly from the chart maybe because there isn’t one.
This would be even better demonstrated if the bottom chart were extended to 440ppm on the right axis at the displayed scale
the correlation will be to TOTAL forcing, not just C02 Forcing.
Been there, done that, doesn’t work either.
Now a believer in orbital solar forcing!
There seems to be some agreement of the temperature proxy line with the Chinese Records that go back to 3,500 years BP. (My apologies for resubmitting the image but it does create a clear picture over part of the period as demonstrated by Mr Vinos).
Javier,
Agree that Holocene Northern Hemisphere/Arctic temperatures are influenced by local northern summer insolation while Antarctic temperatures and CO2 are influenced by southern summer insolation.
https://wattsupwiththat.com/2020/05/27/the-yin-and-yang-of-holocene-polar-regions/
The Holocene Climate Optimum (HCO) was a warm period that occurred in the interval roughly 9,500 to 5,500 years ago BP, with a thermal maximum around 8000 years BP.
Cleopatra VII was a Ptolemy; she was descended from Ptolemy I Soter, the Macedonian general that became ruler of Egypt after Alexanders death. Chances are she wasn’t descended from the pyramid builders at all.
Cleopatra was a Greek, as you indicate, and is not descended at all from the Egyptian pyramid builders, though it’s possible some native north African blood was part of her DNA. Of course, the Egyptians being on the Mediterranean coast were interbred with other peoples from Europe and west Asia. The so-called “Sea Peoples” of whom the later Egyptian pharaohs’ scribes described on tomb and temple writing,are supposed to come from all over southern Europe, the Med, Anatolia (now Turkey) and what is now referred to collectively as the “Holy Land” – their invasion well preceding the the Ptolemaic dynasty.
So who knows who she is actually descended from? After all, all humans are mongrels, having interbred with not only different populations of humans over the eons, but also interbred with other species including Neanderthals.
“Chances are she wasn’t descended from the pyramid builders at all.”
I’m trying to figure out where I said she was. I just mentioned her to make a point about how far back in history the pyramid builders were.
The implication seemed quite clear, otherwise why mention her and the pyramid builders. If you had mentioned, say, the pyramid builders and Hannibal Barca, ‘im wot led the army wiv elephants over the Alps into Italy and played by Alexander Siddig, then I wouldn’t have presumed there to be a linear connection. I do apologise if I read more into it than was intended.
I didn’t get that impression at all. He was just demonstrating how far back in time the events being discussed are. Cleopatra being a rather famous Egyptian and a lot of people regard her time as being “a long time ago”.
There’s less of a gap in time between us and her then there is between her and the pyramid builders.
The only connection is that they were both “Egyptians”.
Thank-you for the apology, but it wasn’t necessary. I see I’m going to have to work on my implication skills–apparently I’m implying things I never intended.
I picked Cleopatra because I thought she would be mostly known. I’m not sure if Hannibal has that same recognition factor.
Here’s an interesting picture. It’s taken from a road that runs from downtown Cortona to past the home where the author who wrote “Under the Tuscan Sun” lives. The straight line is a Roman road. Romans didn’t do curves. If they wanted to change direction–they just did. The body of water off in the distance is Lake Trasimene. It’s where one of Hannibal’s battles took place during the Second Punic War.
The Holocene, Minoan, Roman and Medieval, were all warmer than today and described as Optimums, yet the current gentle warming is described as a catastrophe.
One thing that is curious about the paper is that they divide the Arctic into north of 66º and south of 66º locations, yet by definition, the Arctic is north of 66º. Locations south of 66º are considered part of the mid-latitudes, and at best the sub-Arctic.
In terms of climate, I only consider the Arctic as north of 70º. The polar night -a night that can last from more than 24 hours to 6 months depending on latitude- starts at 72º.
“…a night that can last from more than 24 hours to 6 months depending on latitude- starts at 72º”
. why not 67º? (= 90º – 23º (Earth axis inclination towards Ecliptica)).
Between 67°24’ and 72°34’ it is polar twilight.
The civil polar night is limited to latitudes above 72° 34′, which is exactly 6° inside the polar circle. That is because of the apparent diameter of the Sun.
https://en.wikipedia.org/wiki/Polar_night
The diameter of the sun is estimated as 865,370 miles. Since it is about 93 million miles away, it subtends an angle of 865,370 / 93,000,000 = 0.009305 radians = 0.533 degrees. Where does the 6 degrees come from?
It is possible that the atmosphere can refract some sunlight to the earth’s surface when the sun’s disk is up to 6 degrees below the horizon, which would give an impression of twilight. In clear weather at lower latitudes, this can result in a bright sky in the east before sunrise, or in the west after sunset.
A few degrees north of the Arctic Circle near the winter solstice, there could be a few hours of twilight in the south shortly before and after solar noon. The brightness and duration of this twilight would decrease with increasing latitude.
I believe civil night refers to how dark it is. If the sun is just barely below the horizon, it is still quite light. Twilight at best.
Steve: It’s the twilight zone.
https://en.wikipedia.org/wiki/Twilight#/media/File:Twilight-dawn_subcategories.svg
Holocene climate change
Long term trend (~10 ka): cooling with many multicentennial and multidecadal ups and downs.
Highest point: ~8 ka BP (HCO peak)
Lowest pont: ~0.4 ka BP (LIA minimum)
Holocene subdivision:
The first ~1/2: Holocene Climate Optimum
The second ~1/2: Neoglacial
Prediction: continuation of the long term cooling trend.
Wasn’t the typical length of past interglacial warm periods something like 7-10 thousand years? Fig 15 shows that in the current one after a steady 7 or 8 millennia the cooling has set in. Are we seeing the beginning of the descent into the next glaciation here? If so, we are already 3 millennia into it. Better stock up on coal.
Typically around 10,000 years, although there have been other interglacials that lasted longer so can be up to around 30,000 years. The last 4 interglacials were each around 20,000 years long.
Having said that though, the boundary between interglacial and glacial isn’t that clearly defined (the boundary coming out of a glacial period seems more clear) so, if we are a bit over halfway, we’re likely to see a slow descent into colder and colder weather, fewer and less warm periods and growth in glaciers until we suddenly wake up and realise we’re right in it.
All the more reason to exceed RCP 8.5 and increase FF use 🙂
Since the end of the Holocene Optimum there have been 4 warm periods (not including the Modern one), each about 1000 years apart. The peak of each warm period has been a little cooler than the one before, and the cool period between the warm periods have been a little colder than the one before.
That was certainly a common view in the 1970’s, including held by some (eg Schneider) who became bigtime climate alarmists on the warming side just a few years later.
But all apocalyptic views must be scrutinized with skepticism. Human nature so clearly is vulnerable to gloom and doomism.
If only the science were settled, we’d know if the next glaciation were imminent. But climate science is only in its infancy.
And hasn’t grown much at all in the last 50 years.
The precession cycle that dominates the interglacial/glaciation cycle has a somewhat modulated period around 23kyr.
The same conditions that initiate an interglacial – rising peak NH solar intensity, also initiate glaciation. When northern oceans warm up, there is more moisture n the atmosphere and more snowfall. The snowfall eventually overtakes the snow melt and glaciation begins. But the northern land masses have a limited carrying capacity of ice and the ice shelves eventually limit the ocean peak temperature and that switches conditions to rising sea level that breaks off massive ice sheets that cooled the ocean more. Loss of ice sheets is a tipping point at the depth of glaciation.
The glaciation cycles over the past 500kyr have been multiples of precession cycle.
The only place currently gaining permanent ice extent and elevation is Greenland. The turning point for NH ocean warming was 500 years ago when the mid latitude peak solar hit bottom. It has been rising since. That means ocean surface have been warming for at least 200 years, allowing for the thermal lag, and will continue to warm for the next 8,000 years or so. But the maximum surface temperature is limited to 30C. Just a lot more surface will hit that limit.
Expect new snowfall records this year. And ever year for a long time to come.
https://electroverse.info/prof-nils-axel-morner-the-approaching-grand-solar-minimum-and-little-ice-age-conditions/
If you think a minute amount of global warming is Armageddon, wait till the next ice age bites in the not too distant future
There, you will see real suffering, cold related death spikes and life as we know it, will undergo the most severe challenges of recent history
The alarmists will have something to be truly alarmed about
Alarmism will be one of those luxuries that we’ll likely not be able to afford in an ice age society.
3C difference using 11 sites.
OMG
imagine that.
You alarmists are all up in arms over even less of a difference using fewer sites.