405 thousand year climate cycle discovered related to Earth's orbit around the sun

In ancient rocks, scientists see a climate cycle working across deep time.

A repeating shift in Earth’s orbit spans hundreds of millions of years


Scientists drilling deep into ancient rocks in the Arizona desert say they have documented a gradual shift in Earth’s orbit that repeats regularly every 405,000 years, playing a role in natural climate swings. Astrophysicists have long hypothesized that the cycle exists based on calculations of celestial mechanics, but the authors of the new research have found the first verifiable physical evidence. They showed that the cycle has been stable for hundreds of millions of years, from before the rise of dinosaurs, and is still active today. The research may have implications not only for climate studies, but our understanding of the evolution of life on Earth, and the evolution of the Solar System. It appears this week in the Proceedings of the National Academy of Sciences.

Scientists have for decades posited that Earth’s orbit around the sun goes from nearly circular to about 5 percent elliptical, and back again every 405,000 years. The shift is believed to result from a complex interplay with the gravitational influences of Venus and Jupiter, along with other bodies in the Solar System as they all whirl around the Sun like a set of gyrating hula-hoops, sometimes closer to one another, sometimes further. Astrophysicists believe the mathematical calculation of the cycle is reliable back to around 50 million years, but after that, the problem gets too complex, because too many shifting motions are at play.

“There are other, shorter, orbital cycles, but when you look into the past, it’s very difficult to know which one you’re dealing with at any one time, because they change over time,” said lead author Dennis Kent, an expert in paleomagnetism at Columbia University’s Lamont-Doherty Earth Observatory and Rutgers University. “The beauty of this one is that it stands alone. It doesn’t change. All the other ones move over it.”

The new evidence lies within 1,500-foot-long cores of rock that Kent and his coauthors drilled from a butte in Arizona’s Petrified Forest National Park in 2013, plus earlier deep cores from suburban New York and New Jersey. The Arizona rocks in the study formed during the late Triassic, between 209 million and 215 million years ago, when the area was covered with meandering rivers that laid down sediments. Around this time, early dinosaurs started evolving.

Within ancient rocks in Arizona’s Petrified Forest National Park, scientists have identified signs of a regular variation in Earth’s orbit that influences climate. Here, one of the authors near the research site.
CREDIT Kevin Krajick/Lamont-Doherty Earth Observatory

The scientists nailed down the Arizona rocks’ ages by analyzing interspersed volcanic ash layers containing radioisotopes that decay at a predictable rate. Within the sediments, they also detected repeated reversals in the polarity of the planet’s magnetic field. The team then compared these findings to the New York-New Jersey cores, which penetrated old lakebeds and soils that hold exquisitely preserved signs of alternating wet and dry periods during what was believed to be the same time.

Kent and Olsen have long argued that the climate changes displayed in the New York-New Jersey rocks were controlled by the 405,000-year cycle. However, there are no volcanic ash layers there to provide precise dates. But those cores do contain polarity reversals similar to those spotted in Arizona. By combining the two sets of data, the team showed that both sites developed at the same time, and that the 405,000-year interval indeed exerts a kind of master control over climate swings. Paleontologist Paul Olsen, a coauthor of the study, said that the cycle does not directly change climate; rather it intensifies or dampens the effects of shorter-term cycles, which act more directly.

The planetary motions that spur climate swings are known as Milankovitch cycles, named for the Serbian mathematician who worked them out in the 1920s. Boiled down to simplest terms, they consist of a 100,000-year cycle in the eccentricity of Earth’s orbit, similar to the big 405,000-year swing; a 41,000-year cycle in the tilt of Earth’s axis relative to its orbit around the Sun; and a 21,000-year cycle caused by a wobble of the planet’s axis. Together, these shifts change the proportions of solar energy reaching the Northern Hemisphere, where most of the planet’s land is located, during different parts of the year. This in turn influences climate.

In the 1970s, scientists showed that that Milankovitch cycles have driven repeated warming and cooling of the planet, and thus the waxing and waning of ice ages over the last few million years. But they are still arguing over inconsistencies in data over that period, and the cycles’ relationships to rising and falling levels of carbon dioxide, the other apparent master climate control. Understanding how this all worked in the more distant past is even harder. For one, the frequencies of the shorter cycles have almost certainly changed over time, but no one can say exactly by how much. For another, the cycles are all constantly proceeding against each other. Sometimes some are out of phase with others, and they tend to cancel each other out; at others, several may line up with each other to initiate sudden, drastic changes. Making the calculation of how they all might fit together gets harder the further back you go.

Kent and Olsen say that every 405,000 years, when orbital eccentricity is at its peak, seasonal differences caused by shorter cycles will become more intense; summers are hotter and winters colder; dry times drier, wet times wetter.

The eccentricity of the Earth’s orbit changes slowly over time from nearly zero to 0.07. As the orbit gets more eccentric (oval) the difference between the distance from the Sun to the Earth at perihelion (closest approach) and aphelion (furthest away) becomes greater and greater. Note that the Sun is not at the center of the Earth’s orbital ellipse, rather it is at one of focal points. Note: The eccentricty of the orbit shown in the right image is a highly exaggerated 0.5. Even the maximum eccentricity of the Earth’s orbit—0.07—it would be impossible to show at the resolution of a web page. Even so, at the current eccentricity of .017, the Earth is 5 million kilometers closer to Sun at perihelion than at aphelion. (Images by Robert Simmon, NASA GSFC)

The opposite will be true 202,500 years later, when the orbit is at its most circular. During the late Triassic, for poorly understood reasons, the Earth was much warmer than it is now through many cycles, and there was little to no glaciation. Then, the 405,000-year cycle showed up in strongly alternating wet and dry periods. Precipitation peaked when the orbit was at its most eccentric, producing deep lakes that left layers of black shale in eastern North America. When the orbit was most circular, things dried up, leaving lighter layers of soil exposed to the air.

Jupiter and Venus exert such strong influences because of size and proximity. Venus is the nearest planet to us–at its farthest, only about 162 million miles–and roughly similar in mass. Jupiter is much farther away, but is the Solar System’s largest planet, 2.5 times bigger than all others combined.

Linda Hinnov, a professor at George Mason University who studies the deep past, said the new study lends support to previous studies by others that claim to have observed signs of the 405,000-year cycle even further back, before 250 million years ago.

Among other things, she said, it “could lead to new insights into early dinosaur evolution.” She called the findings “a significant new contribution to geology, and to astronomy.”

Kent and Olsen say that because of all the competing factors at work, there is still much to learn. “This is truly complicated stuff,” said Olsen. “We are using basically the same kinds of math to send spaceships to Mars, and sure, that works. But once you start extending interplanetary motions back in time and tie that to cause and effect in climate, we can’t claim that we understand how it all works.” The metronomic beat of the 405,000-year cycle may eventually help researchers disentangle some of this, he said.

If you were wondering, the Earth is currently in the nearly circular part of the 405,000-year period. What does that mean for us? “Probably not anything very perceptible,” says Kent. “It’s pretty far down on the list of so many other things that can affect climate on times scales that matter to us.” Kent points out that according to the Milankovitch theory, we should be at the peak of a 20,000-some year warming trend that ended the last glacial period; the Earth may eventually start cooling again over thousands of years, and possibly head for another glaciation. “Could happen. Guess we could wait around and see,” said Kent. “On the other hand, all the CO2 we’re pouring into the air right now is the obvious big enchilada. That’s having an effect we can measure right now. The planetary cycle is a little more subtle.”


The other authors of the study are Cornelia Rasmussen and Randall Irmis of the University of Utah; Chris Lepre of Lamont-Doherty; Roland Mundli of Berkeley Geochronology Center; George Gehrels and Dominique Giesler of the University of Arizona; John Geissman of the University of Texas, Dallas; and William Parker of Petrified Forest National Park.

The paper, “Empirical evidence for stability of the 405 kyr Jupiter-Venus eccentricity cycle over hundreds of millions of years,”

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May 8, 2018 12:26 pm

I know what controls our climate. Media spin.

Reply to  Max Photon
May 8, 2018 1:00 pm

And eccentric skeptics!

Reply to  Leo Smith
May 8, 2018 2:29 pm

Elliptical reasoning, in a sort of round about fashion, that.

Reply to  Leo Smith
May 8, 2018 5:13 pm

Manic cycles … alternating between fear of a coming ice age and fear of an overheated world. The historical pattern is clear:

Reply to  Max Photon
May 8, 2018 1:38 pm

+ many!

Reply to  Max Photon
May 8, 2018 2:52 pm


John Harmsworth
Reply to  Max Photon
May 8, 2018 5:31 pm

Lol! You guys are mean. I love it!

old white guy
Reply to  Max Photon
May 9, 2018 5:50 am

those guys were doing ok until their third from last sentence.

Reply to  old white guy
May 10, 2018 3:50 am

my thoughts exactly!

Reply to  Max Photon
May 10, 2018 11:06 pm

+ Offers you many gifts for that factual quip.

May 8, 2018 12:27 pm

Two points of note. First, they make the necessary obeisance in the direction of CO2, without which it’s hard to get published.
Next, they say:

What does that mean for us? “Probably not anything very perceptible,” says Kent. “It’s pretty far down on the list of so many other things that can affect climate on times scales that matter to us.”

“Not anything very perceptible”??? In a 405,000 year cycle, during a human lifespan of ~ 70 years, the variable orbit will change by 70 / 405000 * 2 = 0.02% … so I’d say “Absolutely nothing perceptible”. But hey, that’s not alarmist enough I guess.

Reply to  Willis Eschenbach
May 8, 2018 12:47 pm

Except for its major influence on the current climate in the first place!
Much like if you’re in a van travelling 100 mph, changes in speed of 1 mph over 100 miles are not very perceptible, but it’s quite laughable to claim that the mechanics governing your velocity in the first place are of little consequence. They are confusing the rate at which forces change with the magnitude of the force. The rate at which a forcing changes does not negate whether that forcing is consequential in the first place.
And perhaps they haven’t read up on Super-Interglacials and how they relate to low eccentricity.

Reply to  RWturner
May 8, 2018 1:11 pm

Yup. Climate changes under the influence of superimposed cycles on every time scale.
Not that I necessarily subscribe to the super-tide hypothesis.

Reply to  RWturner
May 8, 2018 1:13 pm

And of course tectonic events like the formation of the Panama Isthmus ~3 Ma, leading to NH ice sheets, and Southern Ocean ~34 Ma, leading to Antarctic glaciation.

Reply to  Willis Eschenbach
May 8, 2018 3:11 pm

Another – and I have a desk dent in my head. The illustration shows eccentricity = 0 – and eccentricity = .5. (If we could use font tags here, that last would be in 144 point…)
Five percent is .05. .5 is fifty percent.
Okay, just deciphered the fine print, very hard to see in dark gray on light gray… The illustrator acknowledges that it is a major exaggeration. But – at least to me – you do NOT do this in a “scientific” illustration.

Reply to  Writing Observer
May 8, 2018 9:11 pm

A more prominent disclaimer on that illustration would be appropriate. On the other hand, 5% eccentricity would be very hard to make out in a drawing.

Reply to  Willis Eschenbach
May 8, 2018 4:39 pm

Unless you hit a tipping point ;*)

Reply to  Willis Eschenbach
May 8, 2018 6:50 pm

Willis –
“= 0.02% … so I’d say “Absolutely nothing perceptible”. But hey, that’s not alarmist enough I guess.”
You want alarming? The real climate control knob, CO2, is at 0.04%, or TWICE as much… we’re toast.

Reply to  Willis Eschenbach
May 9, 2018 7:44 pm

Ah but then you need to plug in the alarmist trope of “thresholds” and “catastrophic equilibrium shifts” etc etc. A tiny little 0.02% may be the butterfly you need to chaos everything into the rubbish bin. DUN DUN DUNNNN

Al Miller
May 8, 2018 12:30 pm

What it’s not manmade CO2? But computer models and sciency stuff….

May 8, 2018 12:41 pm

Whew! I was worried it was only going to be a 400,000 year cycle! Gotta love the precision. 😉

Reply to  PaulH
May 8, 2018 3:06 pm

Ha. Yeah. I thought it would be neat and tidy to have all cycles nicely divisible. Ie 20,000. 40,000. 100,000. 400,000. Cycles. A sort of pi or phi theory.

Reply to  Macha
May 8, 2018 3:57 pm

Personally, I am divided on that.

Reply to  Macha
May 8, 2018 7:11 pm

Actually, if you use a number Base of 1.2180876123986 (compared to our Base 10), it all makes perfect sense!

Reply to  Macha
May 8, 2018 8:04 pm

You are debasing the conversation here. Now please stop it.

Reply to  Macha
May 8, 2018 8:33 pm

You 2 are good. Both made me laugh.

Reply to  Macha
May 9, 2018 7:47 pm

Well the 20k is really about 26k. Then there was the comet impact that triggered the Younger Dryas, which according to Jack Napier of U Buckingham, was a fragment broken off of Comet Encke, and the resulting 7 year meteor showers of the Taurids that are associated with Encke over the past 13,000 years that used to be so tremendous they lit up the night sky with hundreds of thousands per minute.

Reply to  Macha
May 9, 2018 7:51 pm

An impact at the YD is pure fantasy. It’s not even science fantasy, since there is no valid evidence in support of this baseless conjecture.

Reply to  PaulH
May 8, 2018 4:36 pm

It was originally a 400,000 year cycle – but it was felt that such a short cycle might cause a panic

Tom in Florida
May 8, 2018 12:47 pm

The 400,000 eccentricity cycle was already known and produces a longer interglacial during the time of least eccentricity such as we have today. This is why it is expected that the current intergalcial has several thousand years to go. Perhaps this is a additional verification.

Reply to  Tom in Florida
May 8, 2018 1:00 pm

If the eccentricity cycle rules, the Holocene could last another ~30,000 years or more. But axial tilt is the most important cycle in ice sheet formation, so we’re probably not going to be that lucky.

Tom in Florida
Reply to  Felix
May 8, 2018 1:56 pm

Keep in mind that none of the 3 different parameters act alone. They act together in creating the conditions for change. Some changes are small, some are large depending on how they set up with each other.

Reply to  Felix
May 8, 2018 2:33 pm

Yup. They’re superimposed.
Technically there are five Milankovitch cycles, but you’re right that three are the most important: orbital shape (eccentricity), axial tilt (obliquity), axial precession, apsidal precession and orbital inclination.

Reply to  Felix
May 8, 2018 7:03 pm

What about rotation? Over geologic time, is the earth’s rotation speeding up or slowing down? … and what long term effect would be expected for each scenario?

Reply to  Felix
May 8, 2018 7:39 pm

Days are getting longer, as the moon recedes.

Reply to  Felix
May 8, 2018 8:41 pm

Isn’t the Earth due for a shift in the 19,000-21,000 yr cycle of “wobble” of the axis, that which is also related to the precession of the equinoxes? I’ve always wondered if the start of the last interglacial 10,000-11000 yrs ago, the end of the last Ice Age, was due to a axial wobble that tilted the axis and the NH toward the sun, increasing the number of days in summer, shortening the number of days in winter. Or was that just a coincidence?

Reply to  Felix
May 9, 2018 4:46 am

“Days are getting longer, as the moon recedes.” – Felix
Days have actually been getting shorter, on average, since approximately 1870, in spite of lunar recession:
(United Nations Fisheries and Aquaculture Org)
That long-term trend is attributed to core processes, as per this article which has a similar graph:
As it happens, you can use that graph to predict future temperature trends….
“When detrended, the graphs of -LOD and dT are very similar in shape, and it is clear that -LOD runs several years ahead of dT, especially in its maxima. Shifting the -LOD curve by 6 years to the right (Figure 2.2b) results in almost complete coincidence of the corresponding maxima of the early 1870s, late 1930s, and middle of 1990s (Klyashtorin et al. 1998).

Reply to  Felix
May 9, 2018 7:48 pm

We are actually due for a pre-glacial glaciation in about 1500 years. We’ve been slowly cycling into the next ice age since the Minoan Warm period.

May 8, 2018 12:56 pm

“405 thousand year climate cycle discovered”! Why not 404000, or even 406000 years? The author(s) of this Paper must be accountants!

old white guy
Reply to  macawber
May 9, 2018 5:53 am

looks like it supports the article on paleoclimate cycles.

Paul Klamer
May 8, 2018 1:00 pm

“Astrophysicists believe the mathematical calculation of the cycle is reliable back to around 50 million years, but after that, the problem gets too complex,”
Shouldn’t that be, “but before that” or are we dealing with absolute values? We’re counting back 50MY not forward.

Peta of Newark
May 8, 2018 1:13 pm

Its nice they’re connecting dirt to climate though. Not temperature.
I like that.
A lovely example of the disconnect between temperature and climate happened in the UK just last month, possibly in the US also.
Basically, The Peasants were being driven to complete distraction by crap weather.
The crops couldn’t be planted, grass fields for cows/sheep weren’t growing and anyway, the soil was too wet to let them out.
Lambs and other outdoor animals were dying and Scottish farmers were shelling out 5 million beer/whisky tokens,per week, for bedding straw.
(Man, that must’ve hurt – nearly as tight as Yorkshiremen)
My local peasant/grapevine/lightning-rod and general live-wire (Dave) tells me he’s *never* known anything like it.
Yet my datalogger, from its perch in the laburnum tree in my garden, tells me the average temp for the month was 0.5 degC warmer than last year.
In agreement with my nearest Wunderground PWS and the nearest PWS with a long record (near Derby) had its 5th warmest April since it went live in 2003.
So. What gives?
PWS: Personal Weather Station

Reply to  Peta of Newark
May 8, 2018 1:16 pm

If it were like NW North America, then April came in like a lion and went out like a lamb, skewing the average. Here is was cold, wet and windy for most of April, but rapidly switched to above normal after the passage of a front.

Reply to  Felix
May 8, 2018 7:07 pm

In the U.S. east of the Rockies, the average temp for the month of April was the coolest in 20 years.

Reply to  Felix
May 8, 2018 7:40 pm

Yeah, but only before necessary adjustments are made.

M Courtney
May 8, 2018 1:16 pm

Kent and Olsen?
Where’s Lane?

Reply to  M Courtney
May 8, 2018 1:17 pm

Looking skeptical:comment image

John Harmsworth
Reply to  M Courtney
May 8, 2018 5:36 pm

Just keep an eye out for Mr. Mannxyzptlk!

Reply to  John Harmsworth
May 9, 2018 3:21 pm

I was going to correct your spelling, but I get it. Very funny.

May 8, 2018 1:20 pm

So my take home from that is…..if we hadn’t invented all this stuff we’d probably die

Reply to  Latitude
May 8, 2018 1:45 pm

We probably will anyway.

Reply to  JohnWho
May 8, 2018 7:08 pm

… with certitude as great as paying taxes?

Reply to  JohnWho
May 9, 2018 7:50 pm

Speak for yourself. I plan on living through the Singularity

May 8, 2018 1:42 pm

The idea that Jupiter and Venus is partly responsible for all this mishap is fatalism.
We should establish and convene a UN committee to find practical solutions to mitigate this never ending disaster.

Reply to  Chrisb
May 8, 2018 4:49 pm

File a complaint with the Overlords against Jupiter and Venus. Obviously, they are in cahoots about this.

May 8, 2018 1:46 pm

As usual the press releases make it look like they discovered something that was already widely known.
The 400 Kyr cycle is a consequence of Milankovitch theory, and therefore widely known. The 400 kyr cycle has a small but clear effect on climate. During the late Pleistocene it affects the spacing of interglacials that when the orbit is more elliptic take place at 41 Kyr interval, and when is more rounded at 82 or 123 Kyr interval, as currently. The effect is obvious in benthic δ¹⁸O (temperature proxy), between 3 and 5.5 million years ago, as Clive Best noticed in 2011:

Reply to  Javier
May 8, 2018 2:18 pm

Quite Correct. This is not at all a new discovery. The 405 kyr cycle has been verified repeatedly in geological sections of various ages and in various places
For example the Triassic of North China:
Or the Triassic/Jurassic of the Newark Supergroup (the classic case, known for decades):

Reply to  Javier
May 8, 2018 2:34 pm

However using the 405 kyr cycle to explain the longer ice ages since the Middle Pleistocene won’t work. The long glacial cycles have already lasted through more than two whole 405 kyr cycles.

Reply to  tty
May 8, 2018 3:12 pm

The effect is evident.comment image
At higher eccentricity (dotted line), the interval between interglacials drops to 41 Kyr, while the only 123 Kyr interval corresponds to lower eccentricity.
The transition from the 41 Kyr early Pleistocene to the [100] Kyr late Pleistocene is due to the progressive cooling of the planet that makes it more difficult to get out of the glacial default conditions. Only when obliquity, eccentricity, and precession work together in the same direction it is possible to get an interglacial in the late Pleistocene. That is why high eccentricity every 400 Kyr restores the 41 Kyr periodicity for two interglacials.
That is why ~ 65 Kyr of glacial period await the world in about 5000 years.

Reply to  tty
May 8, 2018 3:16 pm

Good news both for more Holocene warmth and a shorter than Late Pleistocene average glacial interval.

Reply to  tty
May 8, 2018 5:35 pm

I agree with Javier. A best estimate deterministic case controlled by the obliquity cycle results in a Holocene cooling descent beginning in about 4 kyrs. The next concurrent increase of these astronomical cycles is interpreted to initiate a future interglacial in approximately 62 kyrs from present day. This will terminate the current glacial cycle making it one of the shortest glacial cycles in the past 450 kyrs lasting approximately 80 kyrs. This plot incorporates a lag time of 6000 to 6500 kyrs of astronomical input and earth’s reaction time.comment image

Reply to  tty
May 8, 2018 6:53 pm

Javier – Are we looking at a 41,000yr cycle missing 0, 1 or 2 beats, as proposed by a paper cited on WUWT a while ago? (I expect that I can find the link if needed). Your comment read like it was based on this.

Reply to  tty
May 8, 2018 6:59 pm

Key climate unconformities occur at the Termination of glacial maximum events. I think your plot is picking up secondary interglacial events that occur during the eccentric elliptical cycles quite nicely.

Reply to  tty
May 9, 2018 1:02 am

“The effect is evident”
As long as you don’t go beyond 800 kyr ago – then the whole thing falls apart. Why didn’t the length of glacial intervalls follow the 405 kyr cycle before then?

May 8, 2018 1:55 pm

For one, the frequencies of the shorter cycles have almost certainly changed over time, but no one can say exactly by how much. For another, the cycles are all constantly proceeding against each other. Sometimes some are out of phase with others, and they tend to cancel each other out; at others, several may line up with each other to initiate sudden, drastic changes.

And yet some people have a very hard time grasping the way natural cycles behave, and the difficulties of analyzing them with tools developed for stationary cycles in homogeneous data.

Reply to  Javier
May 8, 2018 5:49 pm

True. Just because some climate relative cycles change their period over time doesn’t mean that they’re not still cycles and not still significant to the climate system. Science can’t always precisely predict when one cycle might trough or peak out, but it can say that the switch will occur, which can be important information.
We know that the Holocene will end and another glaciation occur, but can’t say precisely when this negative event will occur. Human intervention might even be able to stop it, given thousands more years of technological development.

Tom in Florida
Reply to  Felix
May 9, 2018 4:52 am

The thing we do know is that when obliquity is more than 23 degrees and moving towards the maximum at 24.5 degrees AND precession puts NH summer solstice near perihelion AND eccentricity is low an interglacial can occur because that is what the conditions were 14,000 years ago.

Joel O’Bryan
May 8, 2018 2:00 pm

Isn’t this just another way of invoking barycentrism, without using that banned term here at WUWT?

Tom in Florida
Reply to  Joel O’Bryan
May 8, 2018 2:41 pm

No, this is addressing the changes in the Earth’s orbital parameters not the Sun’s position.

Reply to  Tom in Florida
May 9, 2018 7:55 pm

Because Earth’s eccentricity has nothing to do with the Sun’s position, which is determined by, oh, right, Jupiter, Venus, and Saturn, mostly….

Reply to  Tom in Florida
May 9, 2018 8:02 pm

That’s right. Earth’s orbit has only to do with the gravitational attraction of Venus, Jupiter and to a much lesser extent other solar system bodies. The position of the sun in its orbit of the galactic barycenter has little to no effect on Earth.

Reply to  Tom in Florida
May 9, 2018 8:03 pm

On Earth’s orbit, I should say. The plunging of the solar system above and below the galactic plane does however indeed affect our climate, ie producing Icehouse v Hothouse climates.

May 8, 2018 2:09 pm

“On the other hand, all the CO2 we’re pouring into the air right now is the obvious big enchilada. That’s having an effect we can measure right now. The planetary cycle is a little more subtle.”
Nonsense. Whatever effect CO2 is having, it cannot be measured. It’s effect can only be theoretically computed.

Reply to  Kurt
May 8, 2018 2:20 pm

“The planetary cycle is a little more subtle.”
The ice ages are controlled by Milankovich cycles. I wouldn’t classify them as “subtle”.

Rich Davis
Reply to  tty
May 8, 2018 5:03 pm

What nonsense! It’s well-established speculation that the ice ages were caused by Silurians tragically sucking all of the CO2 out of the atmosphere causing their doom. Don’t ask me for physical proof, the models all agree that CO2 is the big enchilada, the master control knob. What other explanation could there be?
I should say “the alleged ice ages”, because any talk of ancient climate variation is pretty controversial without invoking the Silurian connection. For there to have been ice ages, there would have to have been Climate Change (TM) prior to human activity, which is not a rational theory. The natural climate was absolutely pristine, static, in equilibrium, balanced on a knife’s edge, and perfect for 4.5 billion years before capitalism set us careening toward our inevitable tipping point 150 years ago. Just as we now know that there was never any medieval warm period, surely we will Mann up and recognize that there could never really have been ice ages.

Reply to  tty
May 10, 2018 8:10 am

Rich Davis — one phrase. To Serve Mann.

Rich Davis
Reply to  beng135
May 10, 2018 8:19 am

Now I have lost my appetite!

J Mac
Reply to  Kurt
May 8, 2018 2:53 pm

The greater productivity of C3 and C4 plants from CO2 atmospheric enrichment is indeed measurable. Repeated experiments have demonstrated this.

Reply to  J Mac
May 8, 2018 3:05 pm

C3 plants benefit from CO2 up to three times current levels. CAM and C4 plants can get by on very little CO2.

Reply to  Kurt
May 9, 2018 8:05 pm

Rich Davis May 8, 2018 at 5:03 pm
Besides the short-lived Silurians, what of the longer lasting Cambrians, Ordovicians, Devonians, Carboniferians and Permians?

Rich Davis
Reply to  Felix
May 10, 2018 3:29 am

Excellent observation sir. I don’t recall those races from Dr Who, but we still have season 11. Obviously they are missing links in the CAGW or CITLCGW (catastrophic intelligent terrestrial lifeform caused global warming) theory. Wait, we could say anthropomorphigenic instead of intelligent terrestrial lifeform caused and stick with CAGW. As a conservative I like to see religions hold fast to their traditions. We can “morph” the doctrine a little, but the essential point that CO2 is the master control knob is unchangeable dogma.
I wonder why all those races decided to overdo the carbon sequestration technology as soon as they got advanced enough to use it? Seems we have yet another risk to our civilization?

May 8, 2018 2:18 pm

The 400 kyr eccentricity cycle is evident in the glacial cycle duration and interglacial character. Nearly circular orbits during Glacial Cycles IX and V which are MIS 19 and 11, respectively, are short in duration lasting less than 90 kyrs. They have brief mild glacial periods and may have a longer interglacial period such as MIS 11. Since the current Glacial Cycle I is occurring in a nearly circular orbit, scientists project this glacial cycle may be short with the next glacial maximum occurring in 55 kyrs to 100 kyrs.
Glacial cycles that occur during predominantly elliptical orbits are longer in duration (greater than 100 kyrs)such as Glacial Cycles VII and III. They also tend to have interglacial doublet periods (MIS 15a and 15c, MIS 7 a/c and 7e).comment image

May 8, 2018 2:23 pm

I saw an somewhat interesting debate online.
I am a Mechanical Engineer. I do not, nor would I ever, claim to be a scientist, even though we are trained in science and physics and chemistry form the very backbone of our work.
Apparently, from the Al Gore interweb, we can have no real opinion on climate change, unless we are named Bill Nye, who is also an ME, and not a scientist, but plays one on TV. (FWIW, I also didn’t major in English composition…so forgive the potentially butchered sentence)
So to combat that, some people are now trying to paint engineers as scientists, probably as long as they are pro-CAGW.
What say you? Are engineers considered scientists? Do our opinions hold any less weight than any other non-climate scientists? I certainly put more stock in the opinions of meteorologists, geologists, physicists, etc… on the matter over anything I’d have to say.
Just curious of your collective opinions.

Reply to  John
May 8, 2018 2:26 pm

IMO anyone with a STEM undergrad degree has enough relevant background to be able easily to call BS on CACA.

Reply to  John
May 8, 2018 2:29 pm

Or for that matter, anyone with common sense and without an agenda.

Reply to  Felix
May 9, 2018 6:51 am

Logic comes in handy, too.

Reply to  Felix
May 9, 2018 6:59 am

Excerpt: “Logical thinking! You might have heard that phrase a couple of times before, but do you really know what it implies? Logical thinking is to think on the basis of knowledge, what we know, and certainties, what we can prove.”
This is the approach climate science should take. All science for that matter, of course, but many in climate science seem not to use much logic, instead, they speculate about things they can’t prove and call it “settled science”.

J Mac
Reply to  John
May 8, 2018 3:14 pm

From the Oxford dictionary online:
ScientistA person who is studying or has expert knowledge of one or more of the natural or physical sciences.
You damn betcha engineers are scientists! Engineering degrees (BS, MS, PhD) require more mathematics, physics, organic and/or physical chemistry, statistics, thermodynamics, etc. than nearly any equivalent climatologist degree.

Reply to  J Mac
May 8, 2018 3:18 pm

IMO, to be a scientist, you have to practice the scientific method, which leaves so-called “consensus climate scientists” out.

J Mac
Reply to  J Mac
May 8, 2018 4:38 pm

John specifically asked “Are engineers considered scientists?” I provided a specific response. By definition, we are. The definition I cited is repeated nearly verbatim in several other well know dictionaries. It’s ‘peer reviewed and accepted’. Engineers are a subset of the defined ‘scientist’ set. You may add any additional qualifiers that suit your perspective.

Reply to  J Mac
May 8, 2018 5:35 pm

I don’t consider Mann, Hansen, Schmidt, Trenberth, et al to be scientists, which by your definition they arguably are, although their expertise is surely subject to doubt. They are quacks and charlatans.
I agree that engineers can and should be considered scientists, if they practice the scientific method.
But being an alleged “expert” doesn’t immediately qualify anyone as a scientist, IMO. As Feynman famously said, “Science is the belief in the ignorance of experts”. So I have a problem with the definition which you cited.

Reply to  J Mac
May 8, 2018 7:39 pm

Offhand, I would say that anyone who has read Feynman or understood the following would qualify:

Reply to  J Mac
May 8, 2018 7:43 pm

But that great post-modern “scientist”, the Great God Mosh, assures us that Feynman had it all wrong.

Reply to  J Mac
May 9, 2018 10:36 am

May 8, 2018 at 7:39 pm
This short clip from the Feynman lectures is posted here often. If you notice, Feynman is talking about a “new law.” The first word he writes on the black board is “guess.” Any John or Jane Doe can come up with a new law–the only requirement is that experiment must demonstrate it to be true.
It’s interesting how there are many people who think a law is a proven theory. Physical laws are hardly above the hypotheses level in science. The real gold standards are scientific theories.
Sometimes you’ll hear (or read) a person saying, “It’s only a theory.” Apparently those people think that a theory must be proven “true” (and become a law) to be correct. Nothing is further from the truth. If it’s only a theory is saying a lot. The real problem is that hypotheses are often raised to the theory level when there’s no justification for it. Any theory, law, or hypothesis can be proven wrong–the science is never settled.

Nick Werner
Reply to  John
May 8, 2018 4:25 pm

Engineering students at my university were awarded a “Bachelor of Applied Sciences” degree upon successful completion of four years of study. At the time (70’s) the prerequisite to enrol in engineering was completion of the first year of UBC’s four-year science program. So I’ve always thought of myself as having learned enough math and science to consider myself a scientist. The ‘Applied’ qualifier suggests that the work output tends to be more tangible and failure is more likely to be apparent.
My particular branch of engineering — electrical — involves among other things finding weak signals in noisy backgrounds. If you think about the Voyager spacecraft… it’s somewhere far beyond Pluto transmitting a few watts, and we’re still able to receive the data that Voyager sends.
Belonging to a discipline that can solve a problem like that three decades before Michael Mann teased a hockey stick graph out of tree ring measurements should entitle us to have opinions on how robust his conclusion was.
And with regard to professionalism, I’ve noticed that in climate science, perhaps unique among the sciences, awards are given to some of the ‘elite’ whose conduct if they were engineers, would likely have resulted in suspension of their right to practise engineering. Which causes me, rightly or wrongly (probably rightly) to devalue their opinions.

Reply to  Nick Werner
May 8, 2018 5:28 pm


Reply to  John
May 8, 2018 4:52 pm

It may be a case of BS, MS, PhD. (Bull spit, More spit, Piled hip deep).

John Harmsworth
Reply to  John
May 8, 2018 5:58 pm

I wouldn’t say engineers are scientists. Nor would I say they are not competent to have an opinion. If you really want to be an expert however, I suggest you go to divinity school. And fail!

Pop Piasa
Reply to  John Harmsworth
May 8, 2018 7:18 pm

“I’m not a real scientist, I just play one in the movies. But, if I were a scientist I would signal virtue by flying all over the world, endorsing the settled science consensus”

Reply to  John
May 8, 2018 10:29 pm

For my Bachelor of Science four year degree (142 semester hours), I studied chemistry, physics, and mathematics, plus various engineering courses (accounting, stoichiometry, general heat and mass transfer, including radiation into gases, non-Newtonian fluids, electric motors, and strength of materials, etc.), as well as astrophysics and determination of orbits just for fun. My GRE scores included an 800 in Science and 790 in Engineering. In my senior year, I had the third highest score on a comprehensive exam given by the chemistry department to all PChem students, including both Chemistry and ChE majors. I don’t mind being called a scientist, though my education as an engineer was broader than that.

Reply to  jorgekafkazar
May 9, 2018 5:29 am


Reply to  John
May 9, 2018 6:48 am

“What say you? Are engineers considered scientists?”

Reply to  TA
May 9, 2018 6:49 am

I meant to put a “!” instead of a “?” at the end of “absolutely. 🙂

Reply to  John
May 9, 2018 6:53 am

Your post needles me for a reply. Many a field of study can contribute to research and discovery if it happens to find or discover relevant information.
I am also a Mechanical Engineer, also with roots in old agrarian settings. My training (and disposition) led me to discover – better reverse engineer – and old ancient instrument. One anomaly I found was that when built the Earth’s obliquity was very different than what the established wisdom said.
Mechanical Engineering helps you delve into the basics of ‘Obliquity’. You will discover that it is an extrapolation backwards of several formulae which none agree with the measured obliquity at only 3k years back. ME also helps you understand how this was all derived, the choices, and the assumptions.
Now in around 1936 someone called GF Dodwell, an astronomer, also found that the present understanding is not wholly correct and that the formulae should be a polynomial with a decaying exponential overriding, as from an abrupt step change.
Funnily, what I found corroborates that. Now that would make the graph of obliquity in the post of Renee May 8, 2018 at 5:35 pm not at all reliable.
As an ME you can also delve into the relationship between tilt (Obliquity) and precession and their interdependence.

Jeff Mitchell
Reply to  melitamegalithic
May 9, 2018 10:30 pm

I would argue with the dictionary definition as described above. Being an expert is not a requirement, nor is being in a particular field. Both attributes are appeals to authority. Both of those attributes can be present in a scientist, but not required. Earlier today I was reading about a pair of high school dropouts who had a business repairing bicycles. By following the scientific method, they gave us modern aviation. They were engineer scientists without a degree. Anyone can be a scientist.

May 8, 2018 2:25 pm

There are many cycles and quasicycles on all time scales. The take away is that the climate is always changing. The whole alarmist schtick is predicated on the assumption that there is some kind of immutable climate from which we must not deviate.

Reply to  commieBob
May 8, 2018 2:28 pm

Correct. And CACA spewers can’t reject the null hypothesis that whatever has happened to climate since c. AD 1945 is any different from before the year in which the level of vital plant food started rising.

May 8, 2018 2:30 pm

One can’t help wonder who these inane press releases are meant for. Anyone with a modicum of geological knowledge will see immediately that it is essentially a big nothing burger. They have simply shown that the Triassic climate in Petrified Forest NP behaved the same way as it did in the Newark Basin at about the same time.
They may have sharpened up the cycle-length a bit, but that is hardly cutting-edge science. But of course it takes a lot less work to discover something that is already known..

Reply to  tty
May 8, 2018 3:30 pm

Usually after informing the PR office at your university of the upcoming publication you get a phone call from someone at the office so you try to explain them what you have done and why it is important. They usually ask for contact details of co-authors or relevant researchers that might add their pov. Then they write something that looks like you just discovered the best thing after the polio vaccine. Finally they release it to the media and agencies with an embargo until the day before the publication (required by the journal). If the research is relevant enough the whole thing might get started by the journal.
Science needs to be sold to the public. The bigger the impact on the media the better for the university, that needs to look as a good research university, and the better for the researcher for his standing at the university and his chances of additional funding. The better also for the journal, that needs to look like a place were the best science is reported to sell subscriptions.
Even WUWT does its bit by publishing it. Obviously nobody in the media does any checking and nearly nobody understands its relevancy. But after all it is coming from reputable institutions, so why check?

Gary Pearse
May 8, 2018 2:30 pm

I like how the climate “orthodoxy” deals with confounding data.
“…But they are still arguing over inconsistencies in data over that period, and the (Milankovic) cycles’ relationships to rising and falling levels of carbon dioxide, the other apparent master climate control.”
There is no way to understand such an obtuse, meaningless statement unless you are familiar with the big unhappy aspect for the climate worriers of the carbon dioxide “relationship” with the cycles. The data of concern is that on all scales, a rise in temperature PRECEDES the rise in CO2, not the reverse. No one is “still arguing”. This is a poison pill for a reader who comes across this information. If “they” are still arguing over it, why don’t they give us the nature of this problematic data and what arguments a4e being presented for the defenders of the orthodoxy. The obfuscutory prose is all the evidence you need to understand that the problem is huge for the proponents of “the other apparent master climate control”
This is why arguments supporting the “consensus” on CO2 warming are so mealy mouthed and laced with insults for impolite sceptics who keep muddying the waters with facts they are trying to bury.

Rich Davis
Reply to  Gary Pearse
May 8, 2018 5:16 pm

of course temperatures precede CO2 rises, CO2 is SO powerful that the temperature anticipates its rise. You have no grasp of causality.
haters gonna hate, deniers gonna deny.

Tom O
May 8, 2018 2:46 pm

I only wonder where all these 10s of millions of layers of rock came from that built up these 10s of millions of years records we so willingly accept. That one was always a difficult purchase for me.

Reply to  Tom O
May 8, 2018 2:50 pm

The process is visible everywhere today. I’ll bet you’ve seen sediment in a river, lake or ocean yourself.

May 8, 2018 2:55 pm

I doubt imperceptible factors are going to be recognizable from Triassic formations. Work it backwards that way, not just forward.

May 8, 2018 3:05 pm

> Scientists … documented a gradual shift in Earth’s orbit that repeats regularly every 405,000 years, playing a role in natural climate swings.
Facepalm. Come on scientists.
Once again. Association is not causation. Repeat until it sinks in.

The Reverend Badger
May 8, 2018 3:10 pm

Gravity !
Woo hoo !!
The mysterious force beween “stuff” which can be a very very long distance apart and yet have a discernable climate effect if the stuff is huge.
I suppose if the stuff is close it has a bigger effect.
Like the moon.
Or perhaps the relatively huge mass of the earth exerting a gravitational effect on the tiny molecules in the atmosphere. Might that have an effect on climate?
Who knows?
Perhaps someone can design a real world experiment (no models, no theoretical only work) to actually look into it?

Tom in Florida
Reply to  The Reverend Badger
May 9, 2018 1:01 pm

Warm air rises, cold air sinks: Gravity.

May 8, 2018 3:13 pm

The most important thing is that the Sun is constant!!! Thereby, not mentioned in the article….

Reply to  jlurtz
May 8, 2018 3:17 pm

Besides its cycles of varying lengths, the sun also gets hotter by one percent each 110 million years.

May 8, 2018 3:24 pm

An interesting bit of actual empirical work. Despite my groaning above about the illustration, pretty good.
One thing, though – eccentricity changes or not – they are once again looking at a single thing. “Silver bullet” as other professions call it. I would note that tectonics had a very big effect also on climate when you get into the time periods that they are talking about. For one thing – 250 million years ago, and for a rather large swatch of time on either side – the majority of the land mass was in the Southern hemisphere. Plus little things like fewer mountain ranges, and the only really major one was oriented pretty much east-west along the equator, not north-south along the west coast as in the Americas. The Tethys Ocean far more enclosed by land, and shallower. So on, so forth, etcetera, etcetera…

Ricjard Bell
May 8, 2018 3:32 pm

“On the other hand, all the CO2 we’re pouring into the air right now is the obvious big enchilada” ……. ??? SO SAD HE HAD TO DROP THIS IN AT THE END !!!!!!!

May 8, 2018 3:37 pm

But there is no real evidence that CO2 has any effect on climate and plenty of scientific rational to support ehe idea that the climate sensitivity of CO2 is zero.

Mark Negovan
May 8, 2018 3:56 pm

Well, from the description of their field work, they could easily earn a little extra money moonlighting for Exxon.
The $970,000 project is a collaboration among Lamont, Rutgers University, the universities of Arizona, Texas and Utah, and other institutions. The drilling, which took place in November and December 2013, took nearly a month, bottoming out at 1,706.5 feet in one hole, then at 830 feet in a second. The deeper hole appears to reach back at least 250 million years–the very start of the Triassic.
Now that looks like some fun work and some very cool science. Real science is cool. Drill baby drill!

May 8, 2018 4:01 pm

Plate tectonics, oceans flows and blockages, solar variations, volcanism, clouds and albedo, winds and oceanic overturning, ghg’s, milankovich cycles, etc. Sounds like a very complex multivariate lot of potential causal variables which are also intercorrelated. Beware of multicolinearity. Possibly, in reality, this is a chaotic system at any given time and it is beyond stupid to note that the other big player is co2, unless, of course, you want acceptance at the academic table and grant money.

James Allen
May 8, 2018 4:02 pm

When I went to the Arizona’s Petrified Forest National Park, the ranger/Nazi/minder on patrol gave us a hard time every time we wandered off the paved trail to take photos of the rocks. This guy gets to drill 1500ft holes in the ground? You’d think photography might be looked upon as a less invasive method of enjoying the park…end of rant

Jeff Mitchell
Reply to  James Allen
May 9, 2018 10:40 pm

I think they make the parks their personal domain. Visitors are merely tolerated.

M Montgomery
May 8, 2018 4:22 pm

As an interested non-scientist, the nutrition and climate sciences have caused me to be skeptical about all science. Unfortunate for the field. I don’t trust new discoveries, and more important, the interpretation thereof. Having said that, I enjoyed the article until the last sentence.

Reply to  M Montgomery
May 8, 2018 4:28 pm

Contrary to the press release, it’s not a new discovery. At best, this research merely confirms previous findings and maybe offers a little more precise cycle length.
Corrupted consensus climate science has given genuine science a bad name. But the evidence for the existence of Milankovitch cycles is based upon observation of the real world, not GIGO models. Earth does wobble on its axis, the tilt of which does change in a 41,000 year cycle. Its orbit around the sun does alter eccentricity on a period of 405,000 years.

May 8, 2018 5:04 pm

They have the axial wobble at 21,000 years.
I have it at 25,920 years. The polar axis moves one degree in space every 72 years. 72 X 360 = 25,920. So, pfffftttt!
And my very crude Excel bar chart shows a distinct wave form in length of cold periods, with warm periods following the same wave form, but shorter with only one exception. So in view of that, yes, it’s entirely possible that we are slowly coming to the end of this warm period. If so, precipitation rates and volumes should change and seasons likewise.
In the Wisconsin glacial maximum, the southern border of the ice fields reached to the southern part of Wisconsin. It’s likely that the weather was considerably different then, also.
I wonder if that would restore the Pastorouri Glacier.

Reply to  Sara
May 8, 2018 5:40 pm

Earth’s axis completes one full precession cycle approximately every 26,000 years. At the same time, the elliptical orbit rotates, more slowly, leading to a 21,000-year cycle between the seasons and the orbit, which is what matters for climate.

Reply to  Sara
May 8, 2018 6:03 pm

During the lead up glacial maximum, the jet stream was far more prone to splitting and looping then it is now.
This meant that the jet stream was often pushing up into the Arctic and flushing cold air down across N America and NW Eurasia. Which at the same time increased jet stream activity in the eastern Pacific would have drove up warm moist air from the Gulf of Mexico to meet up with this cold air coming south over N America. Resulting in huge snow storms over NE America.

Reply to  taxed
May 8, 2018 6:05 pm

“While” not “Which”

Reply to  taxed
May 8, 2018 6:08 pm

“Driven”, not “drove”.
Sorry. Grammar F@scist here.

Reply to  taxed
May 8, 2018 6:35 pm

To get a slight idea of what l mean, take a look at the jet stream activity in and around the Arctic over the next 7 days on Nullschool. Because we are very lucky the weather is playing ball at the moment in showing us a taste of what was likely going on during glacial maximum. In terms of the jet stream patterning of course rather then the harsh climate.

Reply to  Sara
May 8, 2018 8:15 pm

Taxed and Felix, consider this: when (NOT IF) the next glacial maximum occurs, the CAGWers/WArmians/Greenbeans will be completely in denial about it until they discover – to their horror! – that technology they are dependent on (i.e., addicted to) has failed them and they will have to figure out how to kill their own food and cook it without a microwave.
They will show up at your doors, cold and hungry, wanting to use the bathroom and charge their tablet phones, and you will be able to say ‘No. You are a ecohippies. Now go away.’ and shut the door on them.
It is a dream I occasionally have. What if the snow in Quebec doesn’t melt next spring, and the Upper Peninsula of Michigan remains mostly icebound?

J Mac
Reply to  Sara
May 8, 2018 8:58 pm

Just imagine the hordes of UP’ers descending on Niagra, Pembine, and Beecher WI !!
Oh, the Humanity! };>)

May 8, 2018 5:34 pm

I thought Michael Mann was good with tree rings. These guys put him to shame. Seriously, Am I missing something or are scientists coming up with findings based on the flimsiest indirect evidence one could possibly imagine?

Reply to  daveandrews723
May 8, 2018 5:44 pm

This isn’t like Mann’s tree rings. This is science, but it’s being oversold as something new and exciting. It’s just a possibly more precise estimate of the duration of the eccentricity cycle, which is a well established astronomical phenomenon.

John Harmsworth
Reply to  daveandrews723
May 8, 2018 6:18 pm

Mann’s tree rings were selected to help show the result he wanted. Then he invented some third rate math to apply to his data to “prove”the results were real when they were garbage. These guys are probably honest. That’s the difference.

May 8, 2018 6:42 pm

“Kent and Olsen say that every 405,000 years, when orbital eccentricity is at its peak, seasonal differences caused by shorter cycles will become more intense; summers are hotter and winters colder; dry times drier, wet times wetter.”
I blame global warming! It’s all about fossil fuels and carbon and stuff.

Reply to  Allan MacRae
May 8, 2018 8:18 pm

Has anyone besides me considered the effect of a glacier slowly oozing south and crunching Apple’s new proposed data center to smithereens? Or squishing Google’s hallowed data halls flat?

Tim Savge
May 8, 2018 8:47 pm

Very informative article. Perhaps your authors can explain if these Milankovitch cycles have been taken into account by current so called climate scientists? If not then all their models predicting climate doom maybe incorrect. Is this possible?

Reply to  Tim Savge
May 8, 2018 9:51 pm

So-called “climate scientists” can take no account whatsoever of natural climate change, because no one knows how nature works in all its ramifications. Their GIGO models are worse than worthless piles of stinking, steaming garbage, which have cost the world trillions in treasure and millions if not tens of millions of precious human lives. Not to mention the birds and bats.

May 8, 2018 11:19 pm

“But they are still arguing over inconsistencies in data over that period, and the cycles’ relationships to rising and falling levels of carbon dioxide, the other apparent master climate control.”
Yeah, they just had to mention carbon dioxide and its great influence on climate. <_<

May 8, 2018 11:27 pm

The reinvention of the wheel is just part of the necessary process of verification of science, and this 405k paper just indicates that the perpetrators have not had time to read all of the proximal, let alone distal literature, as once upon a time one could. We are frequently reminded in breathless tones how people from lower socio-economic backgrounds tend not to be as successful academically as their higher and luckier peers – always as if it was a new discovery. This paper at least has stimulated some interesting discussion on the interlaced effects of different cycles. I wonder if their calculations took into account the mysterious ninth planet with its 15,000 year inclined orbit, which has recently been accused of causing the tilt in the sun’s axis?

Ed Zuiderwijk
May 9, 2018 12:14 am

No. The CO2 is not the big enchillada. It is the big red herring.

May 9, 2018 1:18 am

Milankovich cycles have one very useful characteristic. They are strictly cyclical, making it fairly easy to isolate them from all the other factors that influence climate. Actually they seem to be a rather minor factor most of the time, though very useful for geologists. Counting Milankovich cycles is a recognized method for estimating the length of geologic intervals.
However in an “icehouse climate”, like the one we are living in, this ordinarily minor effect is enough to shift the climate between glacial and interglacial states. However it is the 41,000 year obliquity cyle that is the dominant one in this context.

May 9, 2018 1:37 am

Venus is the nearest planet to us–at its farthest, only about 162 million miles
Someone ought to check that figure.

Tom in Florida
Reply to  oldbrew
May 9, 2018 11:38 am

Rounding off, Venus is 67 million miles from the Sun, Earth is 93 million miles from the Sun. Add them together and you get 160 million miles when Venus is on one side of the Sun and Earth is on the other.

May 9, 2018 1:43 am

Well, now I’ve read the actual paper (http://www.pnas.org/content/early/2018/05/01/1800891115) and we may have been unfair in our comments here, due to an exceptionally idiotic press-release.
What they have done is essentially to take the well-known Milankovich-based chronology from the Newark Supergroup and correlate it with a drill-core from the Chinle Formation. The Chinle Formation can be precisely dated at multiple points by volcanic ash layers supported by magnetostratigraphy. Through this they have proven that the 405 kyr cycle actually was 405 kyr (their actual result is 404 kyr) long back in the late Triassic, which was not certainly known before (celestial mechanics can’t be extrapolated reliably that far back). Also that deposition in the Newark Basin was continuous without any major hiatus.
And that is all they have claimed to have done. A minor but useful contribution to stratigraphy/chronology and astronomy. The rest is PR fluff and ignorance.

Reply to  tty
May 9, 2018 2:07 am

The amount of CO2 in the atmosphere was 2000-5000 ppm during this interval, but apparently nothing very horrific happened.

Reply to  tty
May 9, 2018 11:48 am

I agree with you, but Rothman, Copse and Geocarb III show lower than that during the Triassic:comment image
And Geocarb has CO2 rising rapidly in the following Jurassic Period.

May 9, 2018 6:32 am

The orbital periods of Jupiter and Venus with respect to the Earth do not just affect the oblateness of the Earth’s orbit, they have also affected the current precession rates of the line-of-nodes and the line-of-apse of the lunar orbit. This means that the orbital periods of Venus and Jupiter may indirectly affect the Earth climate system via the influence of the lunar tides.
We know that the strongest planetary tidal forces acting on the lunar orbit come from the planets Venus and Jupiter. In addition, we know that, over the last 4.6 billion years, the Moon has slowly receded from the Earth. During the course of this lunar recession, there have been times when the orbital periods of Venus and Jupiter have been in resonance(s) with the precession rate for the line-of-nodes and the line-of-apse of the lunar orbit ( Cuk 2007). When these resonances have occurred, they would have greatly amplified the effects of the planetary tidal forces upon the lunar orbit ( Cuk 2007).
Hence, the observed synchronization between the precession rates for the line-of-nodes and line-of-apse of the lunar orbit and the orbital periods of Venus, Earth, and Jupiter, could simply be a cumulative fossil record left behind by these historical resonances.
This could explain why:
(1/(2DY) + (1/(9FMC) = 1/SEV
where DY = Draconic year = 0.948978 sidereal years
FMC = Full Moon Cycle = 1.127385 sidereal years
and SEV = The synodic period of Venus and the Earth = 1.598660 sidereal years.
[N.B. The length of the Draconic year is set by the precession rate of the lunar line-of-nodes compared to the orbital motion of the Earth about the Sun.]
[N.B. The length of the Full Moon Cycle is set by the precession rate of the lunar line-of-apse compared to the orbital motion of the Earth about the Sun.]
[N.B. The synodic period of Venus and the Earth is the time required for the Earth and Venus to realign in their orbits about the Sun.]
3/(SEV) – 2/(SEJ) = 1/9.055081 – 1/20.292924 – 1/62.006158
where SEV = The synodic period of Venus and the Earth = 1.598660 sidereal years.
________SEJ = The synodic period of Jupiter and the Earth = 1.092066 sidereal years.
9.055081 sidereal years = 8 x (14 Lunar Synodic months) ~ 9.1 year climate cycle
20.292924 sidereal years = extreme Perigean Spring-tidal cycle
62.006158 sidereal years = 31/62 year Perigean Spring-tidal cycle

Reply to  Ian Wilson
May 9, 2018 5:35 pm

I believe that the claim that I have made above is eminently reasonable. This is particularly true since Nickolay Sidorenkov and I have meticulously demonstrated the existence of these connections in our two papers:
Wilson, I.R.G. 2014, Are the Strongest Lunar Perigean Spring Tides Commensurate with the Transit Cycle of Venus?, Pattern Recogn. Phys., 2, 75-93
Wilson, I.R.G. & Sidorenkov, N.S., 2018, A Luni-Solar Connection to Weather and Climate I: Centennial Times Scale, J Earth Sci Clim Change 2018, 9:1, p. 446
DOI: 10.4172/2157-7617.1000446
Addendum to the post above:
3/(SEV) – 2/(SEJ) = 1/9.055081 – 1/20.292924 – 1/62.006158 = 1/H
where SEV = The synodic period of Venus and the Earth = 1.598660 sidereal years.
_____SEJ = The synodic period of Jupiter and the Earth = 1.092066 sidereal years.
_______H = The length of the Hale sunspot cycle = 22.2 sidereal years
9.055081 sidereal years = 8 x (14 Lunar Synodic months) ~ 9.1 year climate cycle
20.292924 sidereal years = extreme Perigean Spring-tidal cycle = 18 Full Moon Cycles
62.006158 sidereal years = 31/62 year Perigean Spring-tidal cycle = 55 Full Moon Cycles

May 9, 2018 10:46 am

Jupiter was in opposition last night. I was going to get my telescope out to do some observing, but I slept instead. Ahhh, the trials and tribulations of the amateur astronomer.

May 15, 2018 4:23 pm

All of this has as its assumption that the orbits of all of the planets are close to what they are now and always have been for hundreds of millions of years. it was not clear to me what exactly was found – from two sets of rocks in Arizona and NY/NJ. The found 405,000 cycles from what year to what year before present? – the only thing I read was magnetic pole reversals sort of agreed in the two samples.The Milankovitch cycles are said to be seen but it wasn’t clear how.Am I wrong to believe that definite climate changes of wetter and drier and warmer and colder in 100 million year old rocks might be a little fuzzy? That there have been major climate changes and extinctions and major definable periods in geology I do believe. Has anybody investigated the possibilities that major changes in the orbits of other planets could have caused these to happen? Like the increasing evidence that the asteroids meteorites have minerals that are more easily explained if they been part of a planet at one time.- the increasing evidence that comets are not iceballs>dirty iceballs>icy dirtballs that just happen to give off xrays but mostly the same as asteroids with different orbits. .
I do find it hard to believe there are so many ?scientists? in entirely different fields that feel obliged to say that CO2 is the major control knob on the climate that we see its effect today.

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