Guest “Surfing the Radcliffe Wave” by David Middleton,
Approximately 34 million years ago (mya), during the Early Oligocene Epoch, the Earth entered its current “icehouse” climate mode, with ice sheets covering Antarctica. After warming up again towards the end of the Oligocene, Earth’s climate began a long cooling trend, punctuated by a brief warm period during the Late to Middle Miocene Epoch.
The Middle Miocene Climatic Optimum (MMCO) was an anomalous warm interval from ~17 to ~14 mya. The incorrect assumption that CO2 is the climate change “control knob” has led to many attempts to link the MMCO to the CO2 and other greenhouse gas emissions related to the Columbia River Basalt Group (CRBG) eruptions. The CBRG eruptions do appear to be coeval with the MMCO…
Flood basalts, the largest volcanic events in Earth history, are thought to drive global environmental change because they can emit large volumes of CO2 and SO2 over short geologic time scales. Eruption of the Columbia River Basalt Group (CRBG) has been linked to elevated atmospheric CO2 and global warming during the mid-Miocene climate optimum (MMCO) ~16 million years (Ma) ago. However, a causative relationship between volcanism and warming remains speculative, as the timing and tempo of CRBG eruptions is not well known. We use U-Pb geochronology on zircon-bearing volcanic ash beds intercalated within the basalt stratigraphy to build a high-resolution CRBG eruption record. Our data set shows that more than 95% of the CRBG erupted between 16.7 and 15.9 Ma, twice as fast as previous estimates. By suggesting a recalibration of the geomagnetic polarity time scale, these data indicate that the onset of flood volcanism is nearly contemporaneous with that of the MMCO.
Kashbohm & Schoene (2018)
These flood basalt eruptions certainly would have emitted a lot of CO2, other volcanic gasses and sulfate aerosols. However the CO2 outgassing was probably only a fraction of what would have been required to explain the MMCO.
Armstrong McKay et al., 2014 estimated that the main phase of the CRBG eruptions, along with “cryptic degassing” of country rock, etc., emitted 4,090 to 5,670 billion tons of carbon over a 900,000 period. This only works out to 5-6 million tonnes of carbon per year… That’s an order of magnitude less than a rounding error. Our current 10 billion tonnes per year is only equivalent to 3% of the total annual sources in the Earth’s carbon budget. Self et al., 2005 found that CO2 emissions from flood basalt eruptions were insignificant relative to the mass of CO2 in the atmosphere and unlikely to have played a significant role in past episodes of “global warming.” Although they did note that the sulfur gas emissions and sulfate aerosols may truly have been unprecedented. However, these would have had a cooling effect on the climate.
Furthermore, there is little evidence of significantly elevated atmospheric CO2 associated with the CRBG.
Neither the MMCO nor the subsequent cooling, leading the growth of the East Antarctic Ice Sheet (EAIS), appear to be driven by changes in atmospheric CO2.
There is no evidence for either high pCO2 during the late early Miocene climatic optimum or a sharp pCO2 decrease associated with EAIS growth.
Pagani et al., 1999
While the cause of the MMCO remains somewhat of a mystery (probably tectonically-driven changes in oceanic circulation), the cause of the subsequent cooling (AKA Middle Miocene Climate Transition or MMCT) may have now been identified.
Our Solar System Crossed ‘Radcliffe Wave’ during Miocene Epoch, Astronomers Say
Feb 25, 2025 by Natali Anderson
As our Solar System orbits the Milky Way, it encounters various environments, including dense regions of the interstellar medium. These encounters can expose parts of the Solar System to the interstellar medium, while also increasing the flow of interstellar dust into the Solar System and Earth’s atmosphere. The discovery of new Galactic structures, such as the 9,000-light-year-long Radcliffe wave, raises the question of whether the Sun has encountered any of them. According to new research, the Solar System’s trajectory intersected the Radcliffe wave in the Orion star-forming region between 15 and 12 million years ago (Miocene epoch). Notably, this period coincides with the Middle Miocene climate transition on Earth, providing an interdisciplinary link with paleoclimatology.
[…]
The Radcliffe wave is a narrow sinusoidal gas structure, which comprises many known star-forming cloud complexes, such as CMa, Orion, Taurus, Perseus, Cepheus, North America Nebula, and Cygnus.
This gas structure, with an estimated mass of 3 million solar masses, appears to coherently oscillate like a traveling wave and it is thought to be part of the Milky Way’s spiral structure.
“Imagine it like a ship sailing through varying conditions at sea,” said Dr. Efrem Maconi, a doctoral student at the University of Vienna.
“Our Sun encountered a region of higher gas density as it passed through the Radcliffe wave in the Orion constellation.”
[…]
The paper, Maconi et al., 2025, was recently published in the open access journal Astronomy & Astrophysics. The authors were very careful to not draw sweeping conclusions, however the correlation between our solar system’s Radcliffe Wave transit and the MMCT is very interesting.
Here are the Miocene temperature and CO2 reconstructions plotted together:
The Radcliffe Wave transit certainly appears to be more likely to have influenced the MMCT than a decline in atmospheric CO2. The notion of celestial climate drivers is not new. The concept is similar to that proposed by Nir Shaviv and Jan Veizer in their 2003 GSA Today paper.
Atmospheric levels of CO2 are commonly assumed to be the main driver of global climate. Independently, empirical evidence suggests that the galactic cosmic ray flux (CRF) is linked to climate variability. Both drivers are presently discussed in the context of daily to millennial variations. To the extent that they actually exist, they should also operate over geological time scales. Here we analyse the reconstructed low-latitude sea surface temperature over the Phanerozoic (past 545 Myr), and compare it with the variable CRF reaching the Earth and with the reconstructed partial pressure of atmospheric CO2 (pCO2). We find that at least 66% of the variance in the reconstructed temperature trend can be attributed to CRF variations arising from solar system passages through the spiral arms of the galaxy, an observation that enables us to estimate the CRF/temperature relationship. Assuming that the entire residual variance in temperature is due solely to the CO2 greenhouse effect, or that one of the reconstructed Phanerozoic pCO2 trends is validated, we can place an upper limit to the long-term “equilibrium” warming effect of CO2, one which is potentially lower than that based on general circulation models (GCMs).
After incorporating their “celestial driver” model, Shaviv & Veizer estimated that the maximum equilibrium climate sensitivity (ECS) was 1.9 ºC per doubling of atmospheric CO2, with a most likely value of 0.5 ºC per doubling. Unknown celestial climate drivers may be the reason that ECS estimates derived from paleoclimatology data are nearly twice that of those derived from contemporaneous instrumental data.
The Radcliffe Wave was only recently discovered (2019), even though it is relatively close (~400 light years) to the current position of our solar system. It was an “unknown unknown” potential climate change driver before the publication of Maconi et al., 2025.
How many other “unknown unknowns” are out there?
References
Armstrong McKay, David, Toby Tyrrell, Paul A. Wilson, & Gavin Foster. (2014). “Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study”. Earth and Planetary Science Letters. 403. 254–262. 10.1016/j.epsl.2014.06.040. Special thanks to David Armstrong McKay for kindly sending me a copy of his paper.
Kasbohm, Jennifer, and Blair Schoene. “Rapid Eruption of the Columbia River Flood Basalt and Correlation with the Mid-Miocene Climate Optimum.” Science Advances, American Association for the Advancement of Science, 1 Sept. 2018, advances.sciencemag.org/content/4/9/eaat8223.
Maconi, E., J. Alves, C. Swiggum, S. Ratzenböck, J. Großschedl, P. Köhler, N. Miret-Roig, S. Meingast, R. Konietzka, C. Zucker, A. Goodman, M. Lombardi, G. Knorr, G. Lohmann, J. C. Forbes, A. Burkert and M. Opher. “The Solar System’s passage through the Radcliffe wave during the middle Miocene”. A&A, 694 (2025) A167 DOI: https://doi.org/10.1051/0004-6361/202452061
Pagani, Mark, Michael Arthur & Katherine Freeman. (1999). “Miocene evolution of atmospheric carbon dioxide”. Paleoceanography. 14. 273-292. 10.1029/1999PA900006.
Royer, D.L., et al. 2006. “Tertiary Paleobotanical Atmospheric CO2 Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology” Data Contribution Series # 2006-021. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
Self, Stephen & Thordarson, Thorvaldur & Widdowson, Mike. (2005). “Gas Fluxes from Flood Basalt Eruptions”. Elements. 1. 10.2113/gselements.1.5.283.
Shaviv, N.J. and Veizer, J. (2003) “Celestial Driver of Phanerozoic Climate?”. GSA Today, 4-10.
https://doi.org/10.1130/1052-5173(2003)013<0004:CDOPC>2.0.CO;2
Tripati, A.K., C.D. Roberts, and R.A. Eagle. 2009. “Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years”. Science, Vol. 326, pp. 1394 1397, 4 December 2009. DOI: 10.1126/science.1178296
Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, K. “Trends, rhythms, and aberrations in global climate 65 Ma to present”. Science 292, 686–-693 (2001).
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buh buh buh, the science is settled! We all know all that is possible to ever know about global warming, which is that the only thing that controls Earth’s climate is how many gas powered SUVs are on the road, and whether we use coal or natural gas to power our electric plants. That’s it, nothing else in the universe could ever possibly matter!
You completely understand.
or could it be he “standsunder”?
Plus: it’s that “Orange Himmler” Trump!! It’s his fault!!
Why are climate scientists slower than the speed of dark on the uptake?
Could it be hypercapnia?
So that’s what Al Gore, Kerry and Greta suffer from.
Maybe hypercapnia is why Greta can “see” CO2.
A shame it can’t tell her what she “sees” means.
How about slippery slidercapnia?
Hypercraptalkia
Except the planetary energy systems, air, water, land, never achieve equilibrium.
Just the rotation of the planet prevents that.
Having mass prevents that. Especially when the inputs are constantly changing.
The picture above suggests that our galaxy stands fixed as the sun is speedin around it passing its spiral arms. Is that a reasonable conjecture?
Douglas Adams informed us thusly:
Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun.
“The [Vogon Constructor] ships hung in the sky in …”
Their eternal seach for “42”.
PS The atomic weight of CO2 is 44.
“Missed it by that much.”
Somebody asked the wrong question.
As far as I am aware the whole galaxy is rotating. According to Wikipedia,
the sun’s rotational period is around 212 million years. https://www.scientificamerican.com/article/a-new-map-of-the-milky-way/
The spiral arm rotation period is between 220 and 360 million years https://arxiv.org/pdf/1003.2489v1
the bar pattern rotation period is between 160 and 180 million years. https://arxiv.org/pdf/2012.10130
Plus, the spiral arms appear to be a wave phenomenon. If they were a physical structure of say, stars, they would wind-up tighter and tighter. The arms are regions with extensive star formation–that’s why they appear brighter. The idea is that some type of pressure wave is moving through the galaxy causing star formation.
Sol takes ~230 million years to go round galactic central. There are two major and two minor arms to wander through…
OK–stupid question time. I was under the impression that the entire Galaxy rotated around the galactic center. So does our solar system– being a part of the galaxy. The information in this post suggests that the solar system is rotating around the galactic center at a different (higher?) rate of speed than the galactic mass itself. If the solar system is part of the galactic mass, how is this possible??, or on the other hand if the solar system behaves differently than the galactic mass–why???
According to Nasa
Yes, the Sun – in fact, our whole solar system – orbits around the center of the Milky Way Galaxy. We are moving at an average velocity of 828,000 km/hr.
Did you feel it?
Just the bugs in my teeth.
https://science.nasa.gov/sun/facts/#:~:text=The%20Sun%20orbits%20the%20center,(720%2C000%20kilometers%20per%20hour).
https://phys.org/news/2015-02-milky-rotate.html#:~:text=It's%20spinning%20at%20270%20kilometers,More%20details%20below.
The Sun orbits the center of the galaxy at a speed of 720,000 km/h.
The galaxy’s rotational velocity is 270 km/s (972,000 km/h).
https://en.wikipedia.org/wiki/Galactic_year#/media/File:Milky_Way_Arms_ssc2008-10.svg
https://commons.wikimedia.org/wiki/File:Milky_Way_Arms_ssc2008-10.svg
I guess that is my question, David. Why does our solar system orbit the galactic center at a different speed than the rest of the galaxy.–slower according to the two links you just posted, but much faster according to the chart in the original post.. Just now thinking about it, I suppose the distance from the galactic center has something to do with the speed of rotation, sort of like the speed of rotation at the outer edge of a windmill blade in order to keep up with the rotational speed of the hub.
Probably shouldn’t let my mind wonder in such technical realms.
You have to forget the simple model of a planet and a satellite when trying to figure out how things orbit around the galactic core.
The problem is that the mass is not only distributed about the entire galaxy, its not distributed evenly.
First, there is more mass close to the center, but there is still mass near the rim.
Secondly, as you survey the galaxy, the amount of mass along each radial is different. (Think of a big clock superimposed on an image of the galaxy. When the hour hand is pointing to 1, there is a certain amount of mass covered by the hour hand. When the hour hand is pointing to 2, there is also a certain amount of mass covered by the hour hand. These two masses will not always be the same.)
As a result of these two facts, the speed at which an object rotates depends on its location compared to all the rest of the mass in the galaxy.
To put it another way, if for any given location, there is more mass between you and the center of the galaxy, your velocity will speed up a bit. If there is more mass between you and the edge of the galaxy, you will slow down a little bit. If there is more mass ahead of you (direction of rotation), then you will speed up a bit, if there is more mass behind, you will slow down.
“The Sun rotates on its axis as it revolves around the galaxy. Its spin has a tilt of 7.25 degrees with respect to the plane of the planets’ orbits.”
A fact that needs explaining, as the Sun’s tilt to the Ecliptic should be zero.
There are the stars, and then there are pressure waves in the interstellar medium, which move at different rates.
Tectonic changes and their induced changes to oceanic currents explain quite well the descent into the Late Cenozoic Ice Age. There is no need to invoke cosmic coincidences by unknown mechanisms. That is more fantasy than science.
They clearly explain the sharp cooling at the onset of the Oligocene. That occurred when the Tasmania-Antarctica and Drake passages opened. The cooling from the Pliocene to the Pleistocene can also be linked to the closure of the Panama Seaway.
This article deals with the Middle Miocene cooling from the MMCO. This has not been clearly linked to s specific tectonic event.
The Middle Miocene cooling is linked to the raising of the Himalayan range.
I think that mostly preceded the Middle Miocene and was more relevant to the Early Miocene cooling
https://opengeology.in/rise-of-himalaya-phases/
The Middle Miocene deformation was largely due to lateral movement and extensional processes.
https://www.sciencedirect.com/science/article/abs/pii/S0040195122002025
While the Himalayas are still slowly rising, the vast majority of the uplift of the Tibetan Plateau occurred in the Late Oligocene and Early Miocene.
https://www.researchgate.net/publication/319867588_Tibet_the_Himalaya_Asian_Monsoons_and_Biodiversity_-_In_what_ways_are_they_related/figures
While there’s always a lot of uncertainty regarding geologic reconstructions, I think one thing is clear: There’s no actual evidence that changes in atmospheric CO2 drove either the MMCO or subsequent MMCT.
What I think this demonstrates is that the climate on the blue dot could be dependent to a greater or lesser degree on a large number of variables, some of which are at cosmological scales.
As they say, correlation does not prove causation, but it is often a good place to start looking.
True… And a lack of correlation tends to rule our causation
Elon posted a meme which read “Every person who doesn’t know that correlation does not prove causation will die.”
So will the rest of humanity…😎
This kind of hard science, and the commentary on it, are the reasons I read this site. Mad props to all of you.
CO2 is obviously a bit player in the world’s temperature. I’ve looked into the space debris idea and it’s obviously going to be minor.
I’ve come to the conclusion that the climate is generally powered by oceans moving heat around the planet. The location of continents and how the oceans move heat around is by far the biggest factor. Siberia isn’t cold because of low CO2 but how far it is from the Oceans.
Today, geologically, much of the energy is used to boil water in the tropics and rain expressing at the tropics and transfer dry air to the poles that come down with the Hadley Cell and Ferrel Cells collide making the deserts of today.
The oceans are very very cold, the coldest they have ever been for the last two million years in the last 480 million years as Antartica sense rivers of cold cold waters through saline density. There is little dense warm waters to counter this so the oceans are very cold. The tropical oceans use more energy to boil water than transferring heat about the planet. If you want to look at times when it was different. One can look at the early holocene when the Arctic was 7 degrees warmer around Svalbard Island than today and there weren’t deserts in the Sahara, the oceans were pushing more waters to the Arctic.
Always love your work. A fan.
Molluscs: https://journals.sagepub.com/doi/abs/10.1177/0959683617715701
Sahara: https://www.pnas.org/doi/10.1073/pnas.2024898118
Neoglaciation: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018gl079773
Started to happen about 5k years ago, with a change in the ocean currents. As shown closer to the poles.
Iceland Reglaciation 4.2K years ago: https://cp.copernicus.org/articles/15/25/2019/
Shows an abrupt decrease in wam waters moving to the arctic.
Panama closure and water flows: https://cp.copernicus.org/articles/5/269/2009/cp-5-269-2009.pdf
Cheers.
Very nice. This is what I zeroed in on.
“After incorporating their “celestial driver” model, Shaviv & Veizer estimated that the maximum equilibrium climate sensitivity (ECS) was 1.9 ºC per doubling of atmospheric CO2, with a most likely value of 0.5 ºC per doubling. Unknown celestial climate drivers may be the reason that ECS estimates derived from paleoclimatology data are nearly twice that of those derived from contemporaneous instrumental data.”
How accurate and reliable do we think these numbers are? 1.9C maximum ESC for a doubling of CO2 but a likely .5C. If these numbers are correct I can’t see how this shouldn’t put the added CO2 causes CAGW notion out of its misery once and for all.
So as we crossed the Radcilffe Wave, what were the proposed mechanisms of action here on earth that were induced that resulted in the cooling phase?
As I read it, the article does not have a firm idea, though something similar to cosmic-wave flux was mentioned – it is also described as an “unknown/unknown” 🙂
Uncertain. Deposition of dust and/or increased cosmic ray flux could have seeded cloud formation. Correlation is the easy bit; causation is the tricky bit… but you have to start with correlation or anticoagulation.
Going through an interstellar dust cloud would reduce the insolation to Earth via scattering of sunlight from the dust particles. I remember reading a sci-fi novel back in my youth (in the 1960s) about humanity surviving a snowball Earth event caused by that very effect by going underground for a century. The story concerned what they found when they came out. If +2.8 W/m^2 could cause catastrophic warming, then -2.8 W/m^2 could freeze us. And a column of dust 115,000,000,000 meters long doesn’t need a whole lot of optical density to attenuate 1,362 W/m^2 by 2.8 W/m^2. If the “dust” is more like gas, it would scatter the higher frequencies (higher energy) more strongly. It is perfectly reasonable to think it could happen. Whether it did is another matter.
“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy” seems particularly apt…