Ice age deferred stymies David Middleton at WUWT

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:

Sea levels and global ice volumes over the past 35,000 years

Comments on this topic are closed. There is a new article on sea level where comments are welcome.

Sou 24 October 2014

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Anthony Watts has seen fit to post a rather silly comment from Eric Worrall about a new PNAS paper on sea level and ice. Anthony also adds his tuppence-worth. (Archived here.)

The paper is from a team led by Professor Kurt Lambeck of The Australian National University (ANU).

A fascinating journey up and down the seas

What the Kurt Lambeck and his co-authors have done is paint a wonderfully vivid 35,000 year history of changes in sea level and major ice sheets.

It's taken me a while to read the paper. In part because the subject matter is provided in rich detail, and in part because I found it so fascinating. It's extraordinarily well written. The authors have managed to cram a huge amount of information into the few words allowed by PNAS, while writing in a manner that a lay person like myself could understand.

A shift in ice ages long ago

Today I came across an interesting article about ocean currents and ice ages, which was published in the early edition of Science on Thursday.

The paper is by Leopoldo Pena and Steven Goldstein and it's about what happened a very long time ago. Around 900,000 years ago, glaciations shifted from happening about once every 41,000 years to only once every 100,000 years. What the scientists describe was a major disruption to the thermohaline circulation between 950,000 years ago and 860,000 years ago. They say that the slowing, or perhaps cessation of deep ocean currents drew down a lot of CO2 from the atmosphere and stabilised the glacials at every 100,000 years.

From ScienceDaily.com:

In a new study in the journal Science, researchers found that the deep ocean currents that move heat around the globe stalled or even stopped, possibly due to expanding ice cover in the north. The slowing currents increased carbon dioxide storage in the ocean, leaving less in the atmosphere, which kept temperatures cold and kicked the climate system into a new phase of colder but less frequent ice ages, they hypothesize.

"The oceans started storing more carbon dioxide for a longer period of time," said Leopoldo Pena, the study's lead author, a paleoceanographer at Columbia University's Lamont-Doherty Earth Observatory. "Our evidence shows that the oceans played a major role in slowing the pace of ice ages and making them more severe."

The researchers reconstructed the past strength of earth's system of deep-ocean currents by sampling deep-sea sediments off the coast of South Africa, where powerful currents originating in the North Atlantic Ocean pass on their way to Antarctica. How vigorously those currents moved in the past can be inferred by how much North Atlantic water made it that far, as measured by isotope ratios of the element neodymium bearing the signature of North Atlantic seawater. Like a tape recorder, the shells of ancient plankton incorporate this seawater signal through time, allowing scientists to approximate when the currents grew stronger and weaker off South Africa.

They confirmed that over the last 1.2 million years, the conveyor-like currents strengthened during warm periods and weakened during ice ages, as previously thought. But they also discovered that at about 950,000 years ago, ocean circulation weakened significantly and stayed weak for 100,000 years; during that period the planet skipped an interglacial -- the warm interval between ice-ages--and when the system recovered it entered a new phase of longer, 100,000-year ice age cycles. After this turning point, the deep ocean currents remain weak during ice ages, and the ice ages themselves become colder, they find.

"Our discovery of such a major breakdown in the ocean circulation system was a big surprise," said study coauthor Steven Goldstein, a geochemist at Lamont-Doherty. "It allowed the ice sheets to grow when they should have melted, triggering the first 100,000-year cycle."

You can read the rest at ScienceDaily.com or, if you have a subscription, read the paper at Science.

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Leopoldo D. Pena and Steven L. Goldstein. Thermohaline circulation crisis and impacts during the mid-Pleistocene transition. Science, 26 June 2014 DOI: 10.1126/science.1249770

Denier weirdness: Wondering Willis Eschenbach builds a strawman out of volcanic dust

Update: New material added below.

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Wondering Willis Eschenbach writes another post about volcanoes, which he's done before on Anthony Watts' fake sceptics' blog, wattsupwiththat.  When he's not speculating that occasional landings at remote airports are causing global warming, Willis is a proponent of a type of Gaia hypothesis.  I believe he calls it his "thunderstorm hypothesis" or "thermostatic hypothesis".  He thinks that the earth is self-regulating when it comes to climate and that it's regulated by tropical thunderstorms or some such thing. I won't go into the detail of his mathturbations in his article (archived here - updated WUWT archive here), but I will make a few observations.

Wondering Willis builds a strawman

First up Wondering Willis builds a strawman.  He talks about an urban legend.  He doesn't state which urban area has this legend but anyone who has read climate science would know that it's not a city in which climate research is carried out. He writes:

The amazing thing to me is that this urban legend about volcanoes having some big effect on the global average temperature is so hard to kill. I’ve analyzed it from a host of directions, and I can’t find any substance there at all … but it is widely believed.

The only volcanoes that have "some big effect on the global average temperature" or indeed any effect that's discernible enough to be measured are quite big volcanic eruptions, especially those that occur closer to the equator (but see update below).  But from what I've read - in the main it takes a lot of detailed analysis to separate the signal of a single volcano from the noise in the temperature record.  Dr Hansen and his colleagues on Pinatubo:

With a single volcano it may be hard to identify a climate "signal" among the large amount of weather and climate "noise", that is, the unforced chaotic fluctuations of the atmosphere and ocean. So the Pinatubo team first looked at the average climate response after the five largest volcanos this century. They found (Figure 1) that there was a small cooling, about 1/4°C (1/2°F), which peaked 1-2 years after the eruption. This tends to confirm that volcanos do cause a small global cooling.

Even so, the effect of a single volcano is temporary because aerosols eventually dissipate.

Willis' inexplicable weirdly low "climate sensitivity"

Another weird thing Wondering Willis writes is this - that climate sensitivity is 0.2 degrees Celsius.  He says:

 ...At the end of the day, what we have is a calculated climate sensitivity (change in temperature with forcing) which is only about two-tenths of a degree per doubling of CO2.

Now that is truly weird.  It's even odder because Willis himself in the very same article put up a chart of global temperature anomalies.  He showed monthly anomalies of HadCRUT4.  I'll show annual anomalies:

Data source: UK Met Hadley Centre

Over that period, global temperatures rose by around 0.8 degrees Celsius while carbon dioxide rose by around 40%.  It has a way to go before it doubles.  Willis inexplicably leaves a rise of around 0.7 degrees Celsius unexplained!

My question to Willis is - what has caused global surface temperature to rise by 0.8 degrees Celsius well before CO2 has doubled, if the climate sensitivity is only 0.2 degrees?  (Willis has stated he is using climate sensitivity to mean the rise in global surface temperature from a doubling of CO2.)

The weirdest thing of the lot (not really, given it's WUWT) is that no-one at WUWT asks him this question.  Not a soul.

How does Willis Eschenbach explain ice ages?

Short answer? He doesn't!

In the comments someone asks a good question.  How does Willis Eschenbach reconcile glaciations and deglaciations with his "thermostatic" hypothesis:

Thomas says:

September 22, 2013 at 10:30 am
Jim S, the emissions from individual eruptions is pretty much negligible. Overall volcanoes emit around 1% of the amount from fossil fuels.

Maybe Eschenbach has written about it before, but I’m a bit confused on how he can reconcile “I hold that changes in forcing only marginally and briefly affect the temperature. Instead, I say that a host of emergent thermostatic phenomena act quickly to cool the planet when it is too warm, and to warm it when it is too cool” with the existence of ice age cycles. Whatever thermostat the Earth has doesn’t seem all that good.

In WUWT-land ice ages are caused by a "snap" and "flip" called "hits the rails"?

Greg Goodman comes to Willis' aid with a sciency explanation (WUWT-style): "we don't know" - but says it could be caused by a magic "snap" and "flip" called "hits the rails":

September 22, 2013 at 10:43 am
Thomas: ” Whatever thermostat the Earth has doesn’t seem all that good.”

what happens at glaciation and deglaciation is clearly different from what happens in between.

There is apparently two stable states ( attractors ) for the climate system. A positive feedback seems to make it snap form one state to the other. We don’t really know what triggers the change-over.

Assuming Willis is basically correct there are limits to the tropical storms range as a feedback mechanism. It cannot go beyond totally clear skies or fully cloud covered tropics. May be when it hits the rails the climate state flips?

I don’t see glaciation as being a major argument against what Willis is proposing.

Greg says that the pseudo-scientists at WUWT "don't really know" what causes ice ages!

In other words, Greg is saying that Wondering Willis' "thermostatic" or Gaia hypothesis is bunkum.  Either that or he thinks that there is some huge sudden impact that has happened at the start of a glaciation and deglaciation.  He doesn't know what this is.

Later in the thread, Willis directly responds to Thomas' question by avoiding it - and in the process shows he can't read his own chart.  Willis says, after quoting Thomas' comment above:

The planet’s temperature varied by ± 0.3°C over the last century. This is a regulation to within about ± 0.1% … on a free-running system which is regulated by nothing more substantial than wind and water.  If you know anything about heat engines, you’ll agree that that is a fantastic governor …September 22, 2013 at 1:10 pm

Willis has shrunk the observed temperature range in his own chart, which is a rise of 0.8 degrees Celsius to a mere ± 0.3°C.  Wondering Willis has a very severe case of confirmation bias!

Climate scientists do know what precipitates an ice age

Although WUWT-ers don't know what precipitates ice ages, climate scientists do.  Climate scientists have found that variations in eccentricity, axial tilt and precession of the Earth's orbit, when combined in a certain way, affect earth's energy balance with resulting feedbacks.  A drop in surface temperature will cause atmospheric CO2 to fall which causes a further drop in surface temperature leading to an ice age; while a rise in surface temperature will cause CO2 to rise, which in turn affects global surface temperature causing the ice to melt. (Milankovitch cycles).

We might get another ice age no sooner than 50,000 years from now, depending on how much longer we use our air as a rubbish dump for waste CO2.

Willis' thunderstorms "when the globe cools"

Here is an insight into Willis' thunderstorm hypothesis - if you can call in an insight.  This is what Willis reckons happens "when the globe cools"!

When the globe cools, the tropical clouds form a few minutes later, the thunderstorms form a few minutes later … and that brings the global temperature back up. September 22, 2013 at 2:19 pm

WUWT-ers might think that Willis invented the notion that the hydrological cycle plays an important part in moderating the weather on earth, but of course he didn't.  It's basic thermodynamics.  When water evaporates it cools the surface. When it condenses into clouds the heat is moved to the atmosphere.  But that's no more than an exchange of energy within the system.  It doesn't explain the extra energy being stored on earth as evidenced by the recent very rapid warming.  The only thing that explains that is the huge increase in atmospheric greenhouse gases.

Still, I expect the WUWT-ers will be relieved by Willis telling them that the earth won't have any more ice ages and that David "funny sunny" Archibald has it all wrong!

Update - Willis is "not even wrong" about Super-Volcanoes

Willis Eschenbach shows he doesn't keep up with the latest science when he says "temperature has always recovered" from supervolcanos and that his "hypothesis" explains this but "models" don't.

September 22, 2013 at 6:15 pm
Jim G says: September 22, 2013 at 5:10 pm A true super eruption of a super volcano might be at odds with your “self regulating” surface temperature hypothesis.

We’ve had supervolcanoes in the past, and the temperature has always recovered. Under the models’ view, that wouldn’t happen … with my hypothesis, it would.
w.

Willis is not even wrong!

From the Max-Planck-Institut für Meteorologie (see especially the last point compared to Willis' "a few minutes later" - my bold italics):

The “Super Volcano Project” is a  crosscutting science projects of MPI-M in cooperation with the Univ. of Cambridge. At present the project involves ca 25 scientists from the MPI-M and 7 external scientists.

The major goal of this MPI-M Earth System Modelling (ESM) project is the investigation of the effects  that volcanic super eruptions have on the climate system, employing the coupled MPI-M Earth System model. ...

• Climate effect of larger volcanic eruptions are weaker and smaller than previously thought. 

• The global temperature signal is determined by the strength of the SO2 emission and not by the latitude of the eruption. 

• Post-eruption oceanic and atmospheric anomalies describe a decadal fluctuation in the coupled ocean–atmosphere system. 

• Improved description of processes acting on multidecadal timescales is pivotal to constrain the climate response to the 1809 and Tambora tropical eruptions. 

• Radiative heating from volcanic ash cause rotation of volcanic cloud, which influences the transport in the first days on local scale. 

• Eruption season has a significant influence on aerosol optical depth and clear-sky shortwave (SW) radiative flux anomalies and for large volcanic eruption also on the all sky SW flux anomalies. 

• Annular mode response after volcanic eruption increases logarithmically with increasing eruption magnitude. 

• Deposition of sulphate to the Antarctic polar ice sheet is strongly dependent on eruption magnitude 

• Mt. Pinatubo eruption causes the observed delay of the QBO cycle in 1991/1992. 

• Post-eruption sea ice anomalies show strong hemispheric differences dependent on the magnitude of the eruption. 

• Bare soil coverage is strongly increasing after a very large volcanic eruption with  fewer trees and more grass. 

• Post-eruption atmospheric CO2 anomalies are explained mainly by changes in land carbon storage in the initial phase. In the longer term, the ocean compensates for the atmospheric carbon loss.

You can also read more on the impact of super-volcanoes here at New Scientist.


Here again is the link to the archived WUWT article that Anthony Watts posted - updated here.