The sine wave shown in the paper (Fig. 1 reference F: ‘Comparison of PC2 (blue) with the difference between 30°N boreal solstice insolation and 30°S austral solstice insolation (orange)’) looks like the 21-kyr combined precession cycle, which isn’t mentioned here. However it does feature in an earlier paper (2015): ‘our record shows that the western Pacific ITCZ migration was influenced by combined precession and obliquity changes.’
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The study focuses on the so-called Intertropical Convergence Zone (ITCZ), a low-pressure trough near the equator whose position and intensity changes seasonally with the position of the sun, says Bremen University @ Phys.org.
Trade winds from the northern and southern hemispheres meet here. This results in heavy cloud formation and heavy rainfall.
To analyze how the ITCZ has changed over the past 30,000 years, researchers use the stable oxygen isotope δ18O in calcareous deposits in cave systems on land and deposits of calcareous organisms on the ocean floor.
By releasing enormous amounts of water vapor and latent heat into the atmosphere, the position and strength of the ITCZ over the Indo-Pacific Warm Pool (IPWP) is of particular importance for global climate regulation.
While recent studies of the ITCZ have already fundamentally improved our understanding of the mechanism over the past millennia, Mohtadi and his colleagues used empirical orthogonal functional (EOF) analysis to examine the data in relation to precipitation in this and other regions.
The team was able to identify the main components for the size, strength and position of the ITCZ. They came to the conclusion that the inclination of the Earth’s axis and the eccentricity of the Earth’s orbit around the sun have significantly influenced the size of the ITCZ in the past.
Full article here.
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Study: Reconstruct the intertropical convergence zone over the Indo-Pacific Warm Pool with extended records and empirical orthogonal function – PNAS(2024).
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Image: Intertropical Convergence Zone [credit: University of New Mexico]
Tallbloke's Talkshop 
In F the wave repeats after about 21 kyrs as per combined precession.
So stuff other than CO2 significantly influences “climate”…
Some science papers prefer 23 kyr to 21 but one wave here is inconclusive.
In 2346bce the earth changed from an obliquity of about 14degree to about 24deg. In consequence the earth precessed through about 150degree.
How will that effect the proposed ‘arguments’?
No orbital factors needed in climate models, just add CO2! 🙄
JUNE 28, 2024
Climate change to shift tropical rains northward, suggests computer modeling
A study led by a UC Riverside atmospheric scientist predicts that unchecked carbon emissions will force tropical rains to shift northward in the coming decades, which would profoundly impact agriculture and economies near the Earth’s equator.
The northward rain shift would be caused by complex changes in the atmosphere spurred by carbon emissions that influence the formation of the intertropical convergence zones.
https://phys.org/news/2024-06-climate-shift-tropical-northward.html
More climate bollocks from academia!
Obliquity angle looks fairly predictable here…
The tilt reached a maximum of 24.2 degrees about 9500 years ago, and has been decreasing ever since. The tilt is now near the average value, but the rate of change of the obliquity is near a maximum.
http://astro.wsu.edu/worthey/astro/html/lec-precession.html
Oldbrew quote “Obliquity angle looks fairly predictable here”.
That is also an ancient model.
I haven’t read all this, but it has a lot of detail.
I examine the Dodwell hypothesis, that the earth underwent a catastrophic impact in 2345 BC that altered its axial tilt and then gradually recovered by about 1850.
Click to access analysis-dodwell-hypothesis.pdf
Oldbrew you find some interesting material. On your recommendation I do subscribe to the phys.org newsletter. I have found there is a lot of junk from Oz Conversation which has woke contributors from Oz universities. However, occasionally there are some interesting articles with some factual data. Sorry off topic but just have seen this Investigating newly discovered hydrothermal vents at depths of 3,000 meters off Svalbard (phys.org) To me this confirms that natural gas or methane is not a fossil fuel but is made at plate boundaries in high temperature reactions between water and carbonate rocks (mainly limestone). Someone might want to write an article linking where natural gas (and oil) deposits are with old and newer plate boundaries. In Oz Natural gas is mainly occurring in north west where the Australian plate meets the Asian, all through Indonesia, Malayasia, PNG, and NZ has natural gas, There is Natural gas at the African/European plate boundary. The article is however wrong about greenhouse gases which should not include methane.
oldbrew:
Seen your link a decade ago. The details in fig4 ???? Analysis not based on evidence but opinion.
See https://articles.adsabs.harvard.edu/pdf/1979A%26A….73..129W
Wittmann researched his data (which I used). An important date is 173CE where there are two Chinese measurements on same day (interesting history there). They are not evident in fig4 of your link.
That date is important because I connected it to recent research
See https://melitamegalithic.wordpress.com/2022/10/31/searching-evidence-astronomy-for-the-heretic/
In sedimentary records yr 173ce features as a disturbance, which can only be explained by the obliquity disturbance found by the Chinese. Luckily there is an earlier one at ~2345bce (2346bce precise). I had to change from the usual ‘trend’ in graphs to a ‘scatter plot’ which seems to be what is real.
Also interesting here: http://dioi.org/jw07.pdf on page 72 in B3 Quote “That last disability forced Babylonian ephemerides to track celestial bodies’ eccentric mo-
tion not by smooth curves but by crude zigzag functions. Or even, more primitive yet:
step functions!” So the Babylonians had recorded step functions in their observations of the heavens. (I have not yet found the actual data DIO refers to). They were likely doing it right.