Friday, January 15, 2016

Ice age deferred stymies David Middleton at WUWT

Sou | 12:50 AM Go to the first of 8 comments. Add a comment
Anthony Watts has posted another ice age article at WUWT (archived here, cached here). This time, instread of it being an "ice age cometh" article, it's an "ice age isn't coming" article. The WUWT article is by David Middleton, who is one of Anthony's pet deniers. He was writing about a new paper in Nature about how we've deferred one and may possibly defer two major glaciations. We're certainly going to perceptibly affect the climate for more than 100,000 years ahead.

It's been known for some time that we've deferred major glaciations

The fact we've deferred at least one glaciation won't be news to anyone who's familiar with previous work on the subject. The fact we may have deferred two might well be news, although mathematician and astronomer Sir Robert Ball predicted it would take 200,000 years way back in 1906:

Speak no more of the glacial epoch as 80,000 years agone. The glacial epoch is ahead. Sir Robert Ball says that the next ice age is due in 200,000 years. In the course of long periods the earth's orbit round the sun changes from being nearly a circle, as it is now, to a long ellipse or oval, and in the last case the summer may be only 166 days long, while the winter lasts 199 days. There is a short hot summer, followed by a long, excessively cold winter, so that more ice is formed in the cold than can be melted in the warm season.

On purely astronomical grounds, even if geologists had not discovered the ice ages from the records of the globe's surface, astronomers would have demonstrated that ice ages must have happened. When the next chilly epoch arrives posterity may see all Northern Europe under an ice-cap that will o'ertop the highest mountains and last for many thousands of years. 

This new paper follows others that have discussed how we've deferred ice ages. In 2002, Berger and Loutre posited in a paper in Science that we've deferred one major glaciation by emitting so much CO2. In 2003 William Ruddiman suggested in a paper in Climatic Change that we started that deferral thousands of years ago, when we first began to change the landscape. These were followed by a 2005 paper by David Archer and Andrey Ganopolski (the lead author of the new paper), who also wrote how we've deferred the next ice age, and maybe more than one, depending on how much extra greenhouse gas we throw into the air. They wrote:
An anthropogenic release of 300 Gton C (as we have already done) has a relatively small impact on future climate evolution, postponing the next glacial termination 140 kyr from now by one precession cycle. Release of 1000 Gton C (blue lines, Figure 3c) is enough to decisively prevent glaciation in the next few thousand years, and given the long atmospheric lifetime of CO2, to prevent glaciation until 130 kyr from now. If the anthropogenic carbon release is 5000 Gton or more (red lines), the critical trigger insolation value exceeds 2 σ of the long-term mean for the next 100 kyr. This is a time of low insolation variability because of the Earth's nearly circular orbit. The anthrogenic CO2 forcing begins to decay toward natural conditions just as eccentricity (and hence insolation variability) reaches its next minimum 400 kyr from now. The model predicts the end of the glacial cycles, with stability of the interglacial for at least the next half million years (Figure 3c). 
By the way, if you want a more in-depth analysis of Milankovitch cycles, there was a perspective article in Science by Didier Paillard back in 2006, which is worth reading if you can get a copy. (I think it's paywalled, but I'm not sure.)

The point is, a small change in insolation can have a big impact. That's because of the feedbacks. When the forcing is because of slight changes in tilt or wobble it affects the ice cap, which warms or cools the world, which causes more or less CO2 from the ocean to the air and vice versa, which raises or drops the temperature more. The main feedback that causes the warming or cooling is the change in carbon dioxide. A change in atmospheric CO2 has its own feedbacks like water vapour. All these changes then act together to warm or cool the planet.

We may defer not one but two ice ages, even 100,000 years ahead

In this latest paper in Nature, the authors, A. Ganopolski, R. Winkelmann & H. J. Schellnhuber, are suggesting that if we keep going the way we are at present, even if we stop after emitting 1500 Gt of carbon (twice as much again as we've already added to the air), we'll still have a significant impact on climate one hundred thousand years into the future. We'll probably avoid completely the next ice age that would have been due, and significantly diminish if not avoid the one after that.

Below is a chart from their paper, showing what their modeling experiments indicate, that even if we restrict CO2 emissions to a total of 1000 Gt, there will be a lot less ice even after 100,000 years than if we hadn't added any. If we keep going and emit another 1000 Gt on top of the 500 Gt or so we've already added, then the next two ice ages that would otherwise be due will be barely felt, compared to what they would have been without us changing the climate. Click the chart to enlarge it:

The next glacial inception. The top panel shows the temporal evolution of the maximum summer insolation at 65° N. The middle panel shows the simulated CO2 concentration during the next 100,000 years for different cumulative CO2 emission scenarios: 0 Gt C anthropogenic emissions (blue), 500 Gt C (orange), 1,000 Gt C (red) and 1,500 Gt C (dark red line). The bottom panel shows simulated ice volume corresponding to the different CO2 emission scenarios. Individual simulations are shown for the 1,500 Gt C scenario; for the other scenarios, the range is given as shading.  Source: Ganopolski16
From the paper (my emphasis):
Owing to the extremely long lifetime of anthropogenic CO2 in the atmosphere, past and future anthropogenic CO2 emissions will have a strong impact on the timing of the next glacial inception....

Under three scenarios with cumulative emissions of 500 gigatonnes of carbon (Gt C), 1,000 Gt C and 1,500 Gt C, we simulate the ice volume on the Northern Hemisphere for the next 100,000 years. Even for a total of 500 Gt C cumulative emissions, which is only slightly above the present-day value, the evolution of the Northern Hemisphere ice sheets is affected over tens of thousands of years (Fig. 4). In the 1,000 Gt C scenario, the probability of glacial inception during the next 100,000 years is notably reduced, and under cumulative emissions of 1,500 Gt C, glacial inception is very unlikely within the entire 100,000 years.

David Middleton says words have failed him

Back to David Middleton at the climate conspiracy blog WUWT. He posted a slab of text from an article about the paper, written by Alex Morales at Bloomberg, then he wrote:
Words fail me.  I won’t even bother to point out that we are living in an Ice Age which began back in the Oligocene…
Unlike most people, including those at WUWT, David doesn't like the colloquial use of ice age, and insists on using the term in the geological sense. That won't please all the WUWT-ers who normally use the term in the popular sense when they voice their alarm that we are about to head into a new ice age ... any day now.

His nitpick notwithstanding, it's not yet clear why words failed him to the extent that he couldn't write any of his own and had to copy large slabs from other people.

Now there are a few things odd about David Middleton's article. One is that he references charts copied or derived from scientific papers, and clearly accepts the charts, but doesn't accept what is written in the papers. For example, David's first chart is shown below. Despite the label, his chart isn't directly from the paper identified, Zachos01, though it does look to be based on the same data as that in the paper's version. Here's WUWT version:

The box in the lower right of the chart indicates it is from Zachos et al (2001). It isn't, but it's based on the same data. Here is the version shown in the paper itself for comparison. You can click on the image to enlarge it. The part on the left is what is shown in the WUWT chart, except it's shown vertically, the δ18O(%) is used as an indicator of temperature over the past 70 million years.

Humans only occupy the period to the first mark on the left hand side. Not the 10 but the very first mark indicating 2 million years ago. We are used to a cooler world than that experienced by species that emerged ahead of us. The reason David put it up was apparently because he wanted to point out that we are still in the ice age that's been here for the past 36 million years or so.

David then went and posted another chart, this time labelled "after Royer and Beerling (2011), which looks to be modified from Beerling and Royer (2011). The chart from the paper (not from WUWT) is shown below:

Earth’s Cenozoic atmospheric CO2 history by proxy. Deep-sea temperatures3  (upper panel) generally track the estimates of atmospheric CO2 (lower panel) reconstructed from terrestrial and marine proxies following recent revisions (see Supplementary Information). Errors represent reported uncertainties. Symbols with arrows indicate either upper or lower limits. The vertical grey bar on the right axis indicates glacial–interglacial CO2 range from ice cores. The top blue bar indicates approximate timing of ice-sheet development on Antarctica. Horizontal dashed line indicates the present-day atmospheric CO2 concentration (390 ppm).  Source: Beerling and Royer (2011)
The reason David posted the chart was to point out that in aggregate past CO2 levels derived from different sources and particularly those going back twenty million years or so are noisy. This time he contradicted himself, writing:
Nor will I bother to point out that the current atmospheric concentration of carbon dioxide doesn’t even break out of the Cenozoic noise level…
Now you know and I know that there are good estimates of CO2 going back 800,000 years from ice cores. They show that we already exceed those levels by a wide margin.

Data source: EPICA Dome C Ice Core 800KYr Carbon Dioxide Data, Luthi, D., et al.. 2008

Now David Middleton and other deniers might not be concerned that we have entered unknown territory. It's virtually certain that never since humans evolved has the earth had greenhouse gases at these levels. It's likely that never in at least multiple millions of years has the pace of heating been this fast. There's really no period in history that mimics what's happening today. Sure it was hotter in the past than it will get in the next few decades, but there was a lot that was different back then. Not least of which was there were no people, no agriculture, no global trade - and even the continents were in different places.

Does David Middleton pick cherries?

Sorry for the diversion. I said that there were some oddities in David's article. One thing is that David seems to be arguing something or other about the science being suspect. I can only guess that, because he doesn't say what he is arguing anywhere that I can see. Thing is, that both the above charts that he draws on are by scientists who understand what drives climate.

For example, from Zachos01, the authors whose work his first chart is based upon introduce their paper with a description of what causes climate change in the long term, including the concentrations of greenhouse gases:
Much of the higher frequency change in climate (10to 105 years) is generated by periodic and quasi-periodic oscillations in Earth's orbital parameters of eccentricity, obliquity, and precession that affect the distribution and amount of incident solar energy (Fig. 1) (1). Whereas eccentricity affects climate by modulating the amplitude of precession and thus influencing the total annual/seasonal solar energy budget, obliquity changes the latitudinal distribution of insolation. Because the orbital parameters vary with distinct tempos that remain stable for tens of millions of years (2), they provide a steady and, hence, predictable pacing of climate.

The orbitally related rhythms, in turn, oscillate about a climatic mean that is constantly drifting in response to gradual changes in Earth's major boundary conditions. These include continental geography and topography, oceanic gateway locations and bathymetry, and the concentrations of atmospheric greenhouse gases (3).
The question is, does David Middleton accept the above or does he only pick the bits out of the paper that he likes and rejects the rest?

Below is the first sentence from the paper written by the authors of the other chart David used, Beerling and Royer:
Atmospheric carbon dioxide is clearly a primary driver of global temperature change1 , but efforts to slow anthropogenic emissions from fossil fuel burning and land use change are failing 
Again I ask, does David Middleton accept the above or does he only pick the bits out of the paper that he likes and rejects the rest?

In any event, David Middleton doesn't clearly say whether or not he goes along with this new paper or not. He's being very coy. Perhaps a clue is in his last paragraph, where he mysteriously wrote:
So, it’s actually “worse than we thought”… Earth is naturally delicately balanced between a Late Pleistocene glacial stage and the Paleocene-Eocene Thermal Maximum.  So, no matter what we do, George Carlin was right…
What he wrote bore no relation to the segment he pasted immediately before it, which was:
They basically developed a model relating insolation to atmospheric CO2.  If I am reading it correctly, they are asserting that insolation drives changes in atmospheric CO2 which then drives the glacial-interglacial stages.

Then they go on to say “that under natural conditions alone the Earth system would be expected to remain in the present delicately balanced interglacial climate state, steering clear of both large-scale glaciation of the Northern Hemisphere and its complete deglaciation, for an unusually long time.”  
Can anyone see what David Middleton is trying to argue? I can't. He is reading the science correctly. What he thinks "they are asserting" is old science. It's not new. It's the Milankovitch theory, which you are probably familiar with, and which was even hinted at by Sir Robert Ball back in 1906 (before Milankovitch), and is described in the passage above from Zachos01.

From the WUWT comments

As you can imagine, the dullards at WUWT have various conspiracy theories about all this, and are full of the usual denialist contradictions.

Francisco gets a bit excited and writes:
January 13, 2016 at 1:53 pm
An underhanded way to support the establishment’s scam. This is ludicrous!!
We prevented the ice age (during an ice age) with a puny amount of carbon dioxide!! We are super heroes!! SuperCO2!! 

Jay Hope doesn't know about the greenhouse effect and wonders:
January 13, 2016 at 3:07 pm
They never say the ice age will delay the warming. Wonder why? 

skeohane has finally noticed what scientists have been telling him for decades:
January 13, 2016 at 2:00 pm
Ever notice how CO2 is at its peak just prior to re-glaciating, during each inter-glacial period?

ferdberple hasn't heard of Milankovitch cycle, and CO2 might lag temperature when it's a feedback instead of a forcing, but not by as much as he thinks:
January 13, 2016 at 3:49 pm
So how come in your graph, if high CO2 levels lead to high temperatures, please explain why temperatures drop from 130 to 110 KYA, when CO2 levels are at their highest?
Talk about a Pause!! Forget 20 years, we a talking about 20 thousand years of dropping temperatures with high CO2 levels!!

willhaas is playing "stupid", a favourite pastime at WUWT.
January 13, 2016 at 2:02 pm
Forget the science. The Paris Climate Agreement abolishes all forms of climate change, extreme weather events, and sea level rise for now and for all time and we here in the USA do not have to pay for it because we are a poor nation with a large national debt, trade deficit, and unfunded liabilities. Apparently the powers that be have found some way to intimidate the sun and the oceans into providing the ideal climate for everyone, everywhere, all the time.

richardscourtney could be playing the same game of "stupid", or he might have donned his disinforamation hat. Does he really think that CO2 levels are back to 280 ppm? OCO-2 shows CO2 levels around 400 ppm. Richard is dreaming or deluded.
January 14, 2016 at 1:32 am
Brandon Gates: With typical arrogance you assert with no supporting evidence
In typical terrestrial temperatures, water precipitates out of the atmosphere after a short residence time. CO2 does not.

Nonsense! The OCO-2 data indicates a CO2 residence time of less than a year.

And that is supported by the sequestration rate of the pulse of additional CO2 inserted from phytoplankton into the atmosphere in 1989 which was sequestered in three years: a ‘half-life’ of 6 months removes 98% in three years.

There were a couple of people who had faulty memories or misleading text books way back in the good ol' days when they were just nippers. Bloke down the pub said:
January 13, 2016 at 2:04 pm
I remember reading a book about ice ages while I was still at school back in the 70’s. In it there was a theory that the Earth had to get warmer first in order to increase humidity, before extra snow cover triggered the ice age.

While Steve Reddish remembers it this way:
January 13, 2016 at 6:42 pm
Bloke, the theory, as I remember it, was that warming would continue until the Arctic Ocean lost its ice cover, and then the exposed sea surface would provide water vapor to supply sufficient snowfall on the surrounding land to last through the cloudy summers. The Earth would then cool due to the increasing albedo caused by the ever increasing and spreading southward ice sheets.
The residual heat in the oceans would provide several thousand years of of heavy snowfall before loosing enough heat to allow the arctic to ice over again. This would stop the southward advance of the ice sheets and the Earth would slowly recover from this ice age until the Arctic ice thawed again…

u.k(us) is like me, and can't figure out what David Middleton is trying to say. (No-one else at WUWT seems to care. As usual, they just view WUWT as a notice board for conspiracy theorists, on which to post their random thoughts. The article is almost irrelevant for their purpose.)
January 13, 2016 at 7:01 pm
Just a few clips from your post David Middleton:
“Words fail me.”
“I won’t even bother to point out…..”
“Nor will I bother to point out…….”
“By “ice age,” the author probably means …”
I know you got something to say, but you are not saying it.
What is the worst that can happen ?
You get picked apart by all the lurkers, and then your post lives forever on the internet.
So what, at least you spoke up. 

Michael C sums up WUWT "science" but doesn't know it. He and his fellow deniers do have all the tools, 'yet the same ignorance and lack of common sense prevails' at WUWT:
January 13, 2016 at 11:42 pm
“Humans now effectively control the climate of the planet”
I did not bother reading past that sentence
These guys were trained in science?
In 50 years time how will lecturers describe this era? For weeks I have been trying to describe it in a nutshell. I am gobsmacked. When passion and warped agenda drives pragmatic thought and conclusion anything can result
The medieval inquisitions were no more shameful. We have all the tools to know so much better yet the same ignorance and lack of common sense prevails 

James at 48 is scared he's going to be sent to a fascist camp to be deprogrammed.
January 13, 2016 at 8:58 pm
Some of the more extreme warmistas contemplate fascist states that would put skeptics in camps, “de-program” them or even execute them as punishment for AGW. Well, that knife can cut both ways. Imagine the pitchfork carrying mobs if after proclaiming impossibility of the end of the interglacial, the end was reached either on a “natural” time frame or perhaps one hastened by “AGW mitigation?” Yes, that knife can cut both ways. 

ralfellis has his own unique version of the "facts", including - it's anything but CO2:
January 14, 2016 at 1:38 am (excerpt)
Complete nonsense. Here are the facts.
...c. If man is beginning to effect the climate, it is more to do with industrial soot on the ice sheets (and possibly farming dust, when the fields are bare all winter). It is dust-ice albedo that controls the feedback of ice ages and interglacials, not CO2. So this proposal is wrong at all levels. 

Keith Willshaw read the headline in the Bloomberg article up the top of David Middleton's article, which read: The Good News on Global Warming: We've Delayed the Next Ice Age, and, being contrarian, translated it as follows:
January 14, 2016 at 2:24 am (excerpt)
What amuses me is the assumption that deferring a new ice age is a BAD thing.

References and further reading

A. Ganopolski, R. Winkelmann & H. J. Schellnhuber. "Critical insolation–CO2 relation for diagnosing past and future glacial inception." Nature 529, 200–203 (14 January 2016) doi:10.1038/nature16494

A. Berger and M. F. Loutre. "An Exceptionally Long Interglacial Ahead?" Science  23 Aug 2002: Vol. 297, Issue 5585, pp. 1287-1288 DOI: 10.1126/science.1076120 (pdf here)

Paillard, Didier. "What drives the Ice Age cycle?." Science 313, no. 5786 (2006): 455-456. DOI: 10.1126/science.1131297

Beerling, David J., and Dana L. Royer. "Convergent cenozoic CO2 history." Nature Geoscience 4, no. 7 (2011): 418-420. doi:10.1038/ngeo1186 (pdf here)

Zachos, James, Mark Pagani, Lisa Sloan, Ellen Thomas, and Katharina Billups. "Trends, rhythms, and aberrations in global climate 65 Ma to present." Science 292, no. 5517 (2001): 686-693. DOI: 10.1126/science.1059412 (pdf here)

Ruddiman, William F. "The anthropogenic greenhouse era began thousands of years ago." Climatic Change 61, no. 3 (2003): 261-293. doi:10.1023/B:CLIM.0000004577.17928.fa (pdf here)

The Good News on Global Warming: We've Delayed the Next Ice Age - article by Alex Morales at Bloomberg

Scientists say human greenhouse gas emissions have canceled the next ice age - article by Chris Mooney in the Washington Post

Human emissions will delay next ice age by 50,000 years, study says - article by Robert McSweeney at the Carbon Brief

From the HotWhopper archives


  1. I have no idea what he is trying to argue. Anyway, as far as normal people are concerned, deferring ice ages is probably a very good thing. We don't really want them. Fossil fuel reserves are potentially valuable for long term climate stabilisation, if used sensibly.

    We just happen to be at a point where we've done enough deferring of ice ages for the moment, thank you very much, and should now be worried about deferring another PETM (which wouldn't be "P", but you know what I mean).

    I wonder if we're going to go down in the palaeontological record as the Anthropocene Thermal Maximum (oh vey, it were a tad warm back then).

    1. Way I'm reading it, the whole thing was a setup for this meme: "So, it’s actually 'worse than we thought'" I didn't watch the Carlin video, but I think it's the one where he goes off on a rant about how generally f%#$ed humanity is, and IIRC, for a slew of pretty good reasons that didn't have anything to do with AGW. (Contrast his bit about plastics and the planet, which I think was both hilarous and on point, but I digress.)

      Anywho, I pointed out that actually the paper is saying that because of where we are in the orbital forcing cycle, the Holocene is actually better than it has been any other time in the past 800 kyrs and likely would be pretty good for the next 100 kyrs absent our influence. He only locked onto the things I agreed with him on though, which were ticky-tack puzzlings over how some stuff in the abstract was worded.

      Ultimately, the piece ended up being fodder for the usual repetitive talking points, logic be damned if they have anything directly relevant to the actual substance of the paper itself. On the plus side, Richard S. Courtney claimed my third irony meter of the year calling me arrogant.

      David's got another one out today about the PDO, which includes this gem: "Firstly, the Pacific Decadal Oscillation doesn’t drive anything; so it could not be 'playing a role in record-breaking warmth.'"

      Where to begin ....

    2. Oh ok, so you're saying we haven't actually done much deferring anyway? So we can just go back to worrying about having our arses roasted.

    3. Contrail Chook,

      Oh ok, so you're saying we haven't actually done much deferring anyway?

      I hadn't thought of it that way, but let's investigate. First, I do have a small problem with this statement in the abstract:

      The past rapid growth of Northern Hemisphere continental ice sheets, which terminated warm and stable climate periods, is generally attributed to reduced summer insolation in boreal latitudes1, 2, 3. Yet such summer insolation is near to its minimum at present4, and there are no signs of a new ice age5.

      Emphasis mine, and is the problematic piece. Reference 4 is: Berger, A. & Loutre, M. F. An exceptionally long interglacial ahead? Science 297, 1287–1288 (2002): http://www.climate.unibe.ch/~born/share/papers/eemian_and_lgi/berger_loutre02.sci.pdf

      The lone figure of that paper does indeed show 65 N June insolation at a local minimum, however a longer view ...


      ... shows us presently nowhere close, and actually on the cusp of a gradual upturn. That plot is too tiny to see much, but I have the calculated insolation from Berger (1991 I think) and Antarctic temperature reconstructions from Petit (1999). When I go back to what happened after the Eemian interglacial and find the same level of insolation, this is what I find:

      Year Temp Insol
      -116400 -0.6843 482.2423
      -116300 -0.4618 480.8424


      1900 0.0002 481.7857

      I scaled the Vostok temperatures 50% to account for polar amplification. So my very rough back-of-envelope, not-robust estimate based only on these data is that our CO2 contributions have put us about 0.5 K above where we'd expect to be based on Milankovitch forcing alone.

      I don't disagree with these authors that we may have deferred the next "scheduled" glaciation, in my mind that was already pretty well established by prior works. I do have a niggling question that our emissions averted a "full-blown" ice age this cycle. Like I said previously, I think it's kind of a ticky-tack objection, but FWIW there it is.

  2. It seems like he knew he had to write something about it because it involved typical arrogant climate scientists making sweeping predictions of catastrophe. The angle we are meant to take the Carlin piece I think is that of 'we are powerless to do any of this' but the idea of avoiding an ice age is quite attractive (even though is wasn't due for millennia) and involves accepting the power of CO2. The result means trying to pull an odd balance of not saying anything clearly. He is a victim of trying to satisfy everyone who is against action on CO2.

  3. Here's a tip. Don't invest your retirement savings in mammals

  4. "Here's a tip. Don't invest your retirement savings in mammals."

    Not large ones at least. Absent immediate and profound cultural change, humans are almost certain to instigate the demise of much (if not all) of the remaining high-end megafauna on Earth.


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