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« Antarctic fox | Main | Repeal the Climate Change Act »

Antarctic fox

I think I've mentioned that there was a certain amount of fraternisation across party lines at the reception after the Cambridge Conference. Josh and I had a nice chat to Dr Emily Shuckburgh, who works at the British Antarctic Survey as well as being a scientific adviser to the Department of Energy and Climate Change.

Since that time we've exchanged a few emails and, with my recent blog posts touching on the issue of ocean heat mixing, Dr Shuckburgh thought her own research might be of interest:

Here's Dr Shuckburgh's introduction:

"Sometimes you have to go to the ends of the earth in the pursuit of scientific progress. The oceans cover 70% of our planet and yet there is still much we don’t know about the flow of water around and through them.

To predict future climate we need to find out how global ocean flows may be changing over time. Some ocean waters are very salty and some are very cold. The big unknown is how much these different waters mix together because this has a massive effect on ocean flows.
For a while now scientists have suspected that there are a few key mixing hot-spots in the world’s oceans and that one of them may be in Drake Passage. But how can we check? Well, satellites can give us information about the sea surface, but to look below the surface we are largely dependent on scientists going to sea and taking measurements themselves.
So recently I helped lead a team of UK and US colleagues to the remote and inhospitable Southern Ocean on a mission to investigate…

The more technical version is on the project website, where there is also a link to a semi-technical description.

And here's Dr Shuckburgh herself.



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Reader Comments (59)

Oh the salinity !

May 22, 2011 at 8:35 AM | Unregistered CommenterJack Hughes

The scientists are getting hotter at an unprecedented rate!

May 22, 2011 at 8:58 AM | Unregistered CommenterFarleyR

There is a saying to the effect that the truth lies somewhere between the opposite ends of the argument. What Dr Emily Shuckburgh reminds me, is first that women scientists can be damned attractive (I married one) ... and that in a multivariable system which is effectively an N dimensional problem, the solution is highly unlikely to lie between two points which is a straight line (1 dimensional) but as this is only one of many dimensions or facets to the problem, the solution is likely to lie somewhere orthogonal to the expected solution.

In plain language, in a debate between whether CO2 or the sun was "what dunnit", the answer is probably the ocean currents.

May 22, 2011 at 9:30 AM | Unregistered CommenterScottish Sceptic

You old devil!

May 22, 2011 at 9:58 AM | Unregistered CommenterFoxgoose

Bearing in mind the self-evident fact (of which we have been reminded countless times) that the "science is settled" and that non-believers are "flat earthers", I wonder why we're bothering to go and take measurements in the Southern Ocean when we have a host of computer models which could surely give us all the information we need to much greater accuracy.


After all, we are sufficiently sure that all our beloved politicians are busily going hell-for-leather to "de-carbonise" the economy, at a cost of Trillions.

Instead of enduring this cruise around Antarctica, couldn't Dr Emily Shuckburgh perhaps get a job helping to build windmills? After all, there is a danger that her measurements might even call into question some minor aspects of the Officially Sanctioned Scientific Dogma.

And that would never do.

May 22, 2011 at 10:10 AM | Unregistered CommenterMartin Brumby

Bearing in mind the self-evident fact (of which we have been reminded countless times) that the "science is settled" and that non-believers are "flat earthers", I wonder why we're bothering to go and take measurements in the Southern Ocean when we have a host of computer models which could surely give us all the information we need to much greater accuracy.

If you were having all that research money thrown at you wouldn't you be tempted to go on the odd cruise, otherwise all that surplus money at the end of the financial year could be reclaimed.

May 22, 2011 at 10:38 AM | Unregistered CommenterBreath of Fresh Air

The importance of Shuckburgh’s research is high. Perhaps some context is worthwhile.

Earth’s climate exists because of heat from the sun. Heat from the sun is most intense in the tropics. The climate system is, essentially, a system that redistributes the heat: it transports heat from the tropics towards the polar regions.

The climate system has two main mechanisms for transporting heat: air (the atmosphere) and water (the oceans). The atmosphere can move quickly, i.e. winds. The oceans move more slowly. The oceans, though, hold vastly more heat than the atmosphere; e.g. the top 15 cm of ocean waters contain more heat than the entire atmosphere.

Over time, say decades, ocean heat transport, i.e. currents, can significantly change. Those changes can have an effect on global heat redistribution—that is, on climate.

At present, our understanding of how different currents flow, and how currents changes over time, is poor. The way to resolve that is to get more empirical measurements, such as those being taken by Shuckburgh for the Drake Passage. During the past few years, new measurements have caused substantive revisions to our understandings of other major currents (e.g. the Atlantic Deep Western Boundary Current and the Agulhas Current). Such revisions affect century-scale climate predictions.

May 22, 2011 at 10:49 AM | Unregistered CommenterDouglas J. Keenan

A USA meteorologist has speculated on the connection between El Nino and the current in the Drake Passage. There is a current running north up the west coast of S. America. The seafloor under the DP is volcanically active. The east-bound current mentioned by Dr. S could be partially diverted by volcanic activity, More cold water moving up the S American coast would stregthen and cool the west bound current off Eucador, causing a La Nina. (according to the speculation). More study of the DP could be well justified. I wonder if she is studying the variability of the seafloor she mentions.

May 22, 2011 at 11:41 AM | Unregistered CommenterRichard Hill

It's vital, as Douglas Keenan says. See also this guest post at Roger Pielke Sr's blog by Leonard Ornstein (emphasis as original):

Local heat content of the ocean closely tracks (temperature (°K) x heat capacity x volume). The heat capacity of liquid ocean water varies only slightly with temperature and density/salinity. Deep ocean water, below the thermocline (DOW) makes up about 90% of the ocean volume, has a temperature of about 3°C (~ 276° K) and a salinity of about 3.5%. Therefore, although the temperature of the DOW is colder than most of the sea surface (e.g., sea surface temperatures, SSTs, range from about 18°C (~ 291°K) to 29°C (~ 302°K) from about ± 50° Latitude to the equator), it stores much more heat than the upper 200 meters or so of the thermocline. The low temperature of the DOW is generated and maintained by a quasi-steady-state process. Deep water formation originates near the two poles, by the downwelling of cold dense surface water to create and maintain the famous thermohaline circulation (THC). Most of the THC ultimately upwells in the southern oceans as the completion of the meridional overturning circulation (MOC), with a delay of more than a millennium The DOW is the most poorly explored and measured volume of the ocean. A small brief slowdown of MOC would not necessarily change the GOHC, but would tend to produce a decrease in global mean SSTs that could decrease the GMST (and visa versa). The causal connections might not be readily observed. Such phenomena as ENSO, AMO and PDO represent quasi-cyclic, moderately well-observed exchanges of near-surface waters with deeper waters. When a volume of water is moved downward, some water must move up ‘to maintain the level of the oceans’. It may move up over a very large area below the thermocline, and so be almost imperceptible, as a thermal signature, or it may appear as Ekman-pumped, wind-driven upwelling, in local coastal areas, like with La Nina. But at present, a significant portion of the heat in near-surface water could be advected into the DOW without being observed because of the sparse sampling at depths below 2 km (Argo buoys go no deeper than 2km).

Coincidentally, the latest post on RP Snr's blog looks relevant too:

Intriguing New Paper “Climate Sensitivity To Changes In Ocean Heat Transport” By Barreiro Et Al 2011

From the abstract (emphasis added):

Using an atmospheric general circulation model coupled to a slab ocean we study the effect of ocean heat transport (OHT) on climate prescribing OHT from zero to two times the present-day values. In agreement with previous studies an increase in OHT from zero to present-day conditions warms the climate by decreasing the albedo due to reduced sea-ice extent and marine stratus cloud cover and by increasing the greenhouse effect through a moistening of the atmosphere. However, when the OHT is further increased the solution becomes highly dependent on a positive radiative feedback between tropical low clouds and sea surface temperature. We found that the strength of the low clouds-SST feedback combined with the model design may produce solutions that are globally colder than the Control mainly due to an unrealistically strong equatorial cooling. Excluding those cases, results indicate that the climate warms only if the OHT increase does not exceed more than 10% of the present-day value in the case of a strong cloud-SST feedback and more than 25% when this feedback is weak. Larger OHT increases lead to a cold state where low clouds cover most of the deep tropics increasing the tropical albedo and drying the atmosphere. This suggests that the present-day climate is close to a state where the OHT maximizes its warming effect on climate and pose doubts about the possibility that greater OHT in the past may have induced significantly warmer climates than that of today.

May 22, 2011 at 11:44 AM | Unregistered CommenterBBD

I'm most disappointed to see that the first four comments on this post all referred to Dr Shuckburgh's physical appearance. There are contexts in which it would be relevant, but a scientific discussion of the mixing of different bodies of ocean water is not one of them.

I do hope Dr Shuckburgh won't be put off from contributing here again.

It might be interesting also to study whether there is a correlation between the southern ocean currents and the paths taken by the Royal Albatross.

As some may know, a number of Royal Albatross breed here in New Zealand, at Taiaroa Head, the entrance to the harbour Dunedin is located on.

When the young albatrosses first take off they do not return until they are ready to breed, years later. In the meantime they live entirely at sea, circling Antarctica a number of times in the process.

May 22, 2011 at 12:33 PM | Unregistered CommenterBruce Hoult

Bruce H. I am not sure it is fair to blame the posters of the first four comments for the tone given that the subject of both this and the next post on this site have the title they do. And of course the impression is re-inforced with mention of "fraternisation".

All pretty dull but I guess in the abscence of any sensible expertise on ocean heat content / mixing and transport you work with what you have.

I guess if you wanted to comment on her demonstrable expertise as an ocean scientist you could seek out her publications which are of course well hidden on her www site under the link "publications":

May 22, 2011 at 1:33 PM | Unregistered CommenterMarcusB

@MarcusB I quite agree that the post title is disappointing also.

May 22, 2011 at 1:48 PM | Unregistered CommenterBruce Hoult

The post title came from our conversation with Dr Shuckburgh. It was a joke she made herself. I checked she was comfortable with the post title before it went up.

May 22, 2011 at 2:04 PM | Registered CommenterBishop Hill

I did not read it as "fraternisation" as much as "fraternisation across party lines".

May 22, 2011 at 2:12 PM | Unregistered CommenterShub

I have met Dr Shuckburgh several times at science conferences myself and totally accept what you say. (Indeed I find it easy to imagine she would smile). But in my opinion I still think you are being cheap. Dr Shuckburgh is not the only woman in marine science, or in Antarctic marine science, or even in the DIMES project.
Many of them would be somewhat less than impressed.

May 22, 2011 at 2:19 PM | Unregistered CommenterMarcusB


Thank you for your comments. I don't mind being an Antarctic Fox; Arctic Foxes are very special creatures and since I often inhabit the polar regions it seems a reasonable description.

I do think that it would be more interesting to return to a discussion of the science though...


May 22, 2011 at 2:20 PM | Unregistered CommenterEmily Shuckburgh

As long as it's not a Falklands Fox.

May 22, 2011 at 2:30 PM | Unregistered CommenterMarcusB

I think this is cool. Or probably quite cold. From the project's case paper

Despite the acknowledged climatic significance of Southern Ocean mixing, direct observations of mixing in the region are lacking, and state-of-the-art theories and models of the Southern Ocean limb of the overturning circulation have to date been based on several defining assumptions (such as that of adiabatic flow in the ocean interior) that are now beginning to be disputed by indirect evidence. In order to assess how Southern Ocean mixing processes should be represented in climate-scale ocean models, we propose to test and, if necessary, redefine the present paradigm of Southern Ocean mixing by obtaining the first systematic measurements of mixing processes in two contrasting regimes

It sounds very worthwhile and very sensible. Empirical science helping advance knowledge. From my simple engineers perspective, we live on a heat engine with warm bits in the middle and heat sinks top and bottom. So anything that helps understand how the heat moves around has to be a good thing when we're trying to understand any potential energy imbalances.

I am curious about a comment made in the paper though:

Our international collaboration stems from the recognition that obtaining the observations needed to challenge the present paradigm of Southern Ocean mixing is beyond the logistic capabilities of any single nation.

Is that really a logistics issue, ie not enough research vessels, personnel or resources, or a funding problem? Given the potential expense of climate change and costs of mitigation proposals, spending money on research like this should be a sensible investment. More funding would presumably allow data collection over a longer timeframe.

May 22, 2011 at 2:52 PM | Unregistered CommenterAtomic Hairdryer

This (pretty lame) sexualisation of the subject is the reason that I as an engineer (and science undergrad in olden days) would prefer a better balance between competent members of both sexes.

I don't want quotas (leading to the promotion of the less competent), but having an innie vs outie should not be a cause for comment.

Respect to Emily herself for "I do think that it would be more interesting to return to a discussion of the science though..."

May 22, 2011 at 3:03 PM | Unregistered CommenterGendeau

Best of luck with looking at a subject of real science though.

The world needs more agenda independant basic research...IMHO

May 22, 2011 at 3:06 PM | Unregistered CommenterGendeau

I was also on that cruise on JCR....hello Emily!
Our glorious leader was the infamous Andy Watson who, despite his professional affiliations, is a thoroughly nice chap. Though I didn't let on that I am a Denier - lest I got the "arsehole" treatment (and made myself unemployable). So I keep on taking the taxpayer's shilling.......

May 22, 2011 at 3:45 PM | Unregistered CommenterBuffy Minton

As the first commenter in this thread whose comments Bruce H apparently didn't find disappointing (and for any who have other problems with irony) I would like comment further that, whatever Dr. Shuckburgh's views on cAGW, I am delighted that someone is out there actually measuring stuff and hoping to better understand how the Ocean Currents (and indeed the Climate) actually work. And I have to hope that the data she produces doesn't get the Jolly Jim Hansen treatment.

Actually, the fact that she is an attractive young woman scientist has a resonance for me at another level.

My big sister (some nine years older than me) got a good degree in Botany, long before the cAGW racket had been thought up. She then embarked on a PhD thesis on the mosses and lichens of South Georgia. She had put a lot of desk and laboratory work into this study and was very much looking forwards to going out to South Georgia to do the necessary field work in addition to the study she had done on other people's specimens.

But then came the bolt from the blue. The British Antarctic Survey decided that they really couldn't send a young woman Scientist out to South Georgia. A place only suitable for real men (and probably for those from Public Schools at that).

So her PhD was downgraded to a MSc and she had to complete her studies in Birmingham. I've never forgotten her disappointment.

So I say, good for Dr. Shuckburgh. I'm glad that the kind of really sexist nonsense my sister was subjected to is now history.

May 22, 2011 at 5:02 PM | Unregistered CommenterMartin Brumby

There is a very revealing comment starting ~1:20 min into the mp3 file.

"So yes, there is a medieval warm period. Life is interesting. The world is interesting. Climate changes. But the changes we are seeing now are different.They are bigger, than the known changes in the historic record. And moreover, and this is the part that I think is important for people to understand: its not just random variability. We know something about the laws of physics and chemistry. ..."

What is revealing in this otherwise usual boilerplate stuff about how to think about the MWP, is the part where she says: "Yes, life is interesting, the world is interesting..."., clearly an inadvertently expressed mild disdain, even an antipathy, for a curiousity-based approach to climate science understanding, as opposed to the supposedly more 'reality-based' interpretation of climatic processes in their proper and fruitful policy-coupled context. 'How quaint of you, David of Bristol' - is what Oreskes is saying here.

"Yeah, yeah, it is interesting. But is it useful?"

Can you imagine the impact the same way of thinking would have had, inside academia? 'Yeah, that is an interesting observation. But we have this other way about thinking about things. Go on, run along now'

'Yes, there is something called nature. But we know we are causing everything.'

Will this kind of frozen thinking not retard the advancement of our understanding of the world around us?

Look at Realclimate today:

The Stockholm Memorandum concludes that we have entered a new geological era: the Anthropocene, where humanity has become the main driver of global change.

Yes, 'concluded' indeed.

May 22, 2011 at 5:20 PM | Unregistered CommenterShub

oops! Wrong thread.

May 22, 2011 at 5:21 PM | Unregistered CommenterShub

"where humanity has become the main driver of global change."

Sun, Oceans, Volcanos, H2O - eat your hearts out

May 22, 2011 at 8:49 PM | Unregistered CommenterMartin Brumby

The first comment ( "Oh the salinity" ) is a parody on the commonly-used line ( "Oh the humanity" ).

Some of the next comments are a bit off-colour - like something from a 70s TV show.

Returning to the substance...

Good that they are taking measurements.

But I'm baffled how a single snapshot can help to understand changes. DJK suggests that the ocean circulations can change over decades so they would need to repeat the observations over decades to discover anything.

They seem too eager to feed something straight into a "global climate broth" before thay have a better understanding of their own field.

I hope this is a false impression based on a superficial reading of their press releases. I really hope thay are going one step at a time:
1) Observe the phenomenon (ocean currents)
2) Form at least one hypothesis
3) Predict something outside the original observations
4) Go back to the ocean and check #3
5) Go back to #2 if it fails.

And before they do any of these

0) Read Feynman's speech on cargo cult science

May 22, 2011 at 10:43 PM | Unregistered CommenterJack Hughes

Hi Jack,

We are not looking at long-term changes in this study. Instead we are trying the understand the basic physics. Mixing of the ocean (both in the horizontal and the vertical) is important for determining climate as it influences the distribution of heat and carbon dioxide in the ocean via the effects it has on ocean circulation. It is also important, as a previous post has indicated, because it is something that is parameterised in climate models. The particular hypotheses we are testing are outlined in the original project proposals, which you can read here if you are interested:


May 22, 2011 at 11:04 PM | Unregistered CommenterEmily Shuckburgh

Dr Shuckburgh
Do you get people telling you: 'why are you studying the circulation et al? Anyway the system has trapped heat and it can't get out even it wanted to, so what difference does it make if the ocean circulates it this way or that.'

We get that from many. (And by 'We', I mean climate skeptics hanging around in blogs).

May 23, 2011 at 3:15 AM | Unregistered CommenterShub

Hur hur hur....

May 23, 2011 at 3:31 AM | Unregistered Commenterbanjo

Hi Shub,

That would be true of the atmospheric circulation, but not of the ocean circulation - at least on the timescales we are interested in (ie decades to centuries). The ocean is deep and the overturning circulation is slow. This means that it takes thousands of years for the ocean to come into equilibrium with a new atmospheric state.

I'll give you a particular example. The temperature changes between ice ages and warm inter-glacial periods cannot be explained solely by changes in incoming radiation by changes in solar radiation from orbital variations. It is believed that a positive feedback involving changes in atmospheric concentration of carbon dioxide is an essential part of the response. Most recent explanations invoke changes to the Southern Ocean storage of carbon dioxide. This can arise via a change to the overturning circulation of the ocean, which may be due to a change in the winds that blow over the Southern Ocean. So understanding what drives the ocean overturning circulation (and mixing is key to this) is important for determining climate. This is a problem that my research group is investigating.


May 23, 2011 at 9:38 AM | Unregistered CommenterEmily Shuckburgh


"wouldn't you be tempted to go on the odd cruise"

I would indeed. But while real scientists like ES head off to the Antarctic, the warmists would doubtless charter a boat to the Maldives...

May 23, 2011 at 10:41 AM | Unregistered CommenterJames P

Emily - first thanks for engaging with us sceptics. Good to see you are evidence based science, with measurements and observations, rather than just computer modelling.

You say that: "The temperature changes between ice ages and warm inter-glacial periods cannot be explained solely by changes in incoming radiation by changes in solar radiation from orbital variations. The temperature changes between ice ages and warm inter-glacial periods cannot be explained solely by changes in incoming radiation by changes in solar radiation from orbital variations. "

While I agree that changes in solar radiation from orbital variations are not suffice to significantly influence climate, it is a big stab in the dark to then assume that it must be CO2 that is responsible. I think it much more likely that Svensmark's hypothesis (on how the Sun's much more variable magnetosphere influences the level of Galactic Cosmic Rays that hit the atmosphere, and the role these play in cloud nucleation) is correct. The work of Nir Shariv's on increased GCR as we pass though our galaxies spiral arms also explains previous warm and cold periods in Earth's history. Are you aware of the work of Svensmark and Shariv and do you not think the GCR hypothesis is a more credible explanation for climate change than very minor changes in the atmospheric concentration of a trace gas?

See and for Spencer's thoughts.

May 23, 2011 at 11:35 AM | Unregistered Commenterlapogus

Hi lapogus,

Data from ice cores (collected by my colleagues) shows that concentrations of atmospheric carbon dioxide decreased by about 30% in the transition from warm interglacial to cold glacial periods. Any complete theory needs to be able to explain and incorporate that observation too.

Personally, based on the evidence we have, I think that a carbon dioxide related explanation is the most credible, but I follow the cosmic rays work with interest. I think it is fair to say that both the observational data and the underlying theory for cosmic rays are less robust at the moment.


May 23, 2011 at 11:58 AM | Unregistered CommenterEmily Shuckburgh


"Most of the THC ultimately upwells in the southern oceans as the completion of the meridional overturning circulation (MOC), with a delay of more than a millennium"

I'd no idea that the process was so extended. It makes the time and scale of warmists' claims for the effects of a few ppm of atmospheric CO2 seem even more hyperbolic.

May 23, 2011 at 11:59 AM | Unregistered CommenterJames P


"concentrations of atmospheric carbon dioxide decreased by about 30% in the transition from warm interglacial to cold glacial periods"

Perhaps an effect, rather than a cause?

May 23, 2011 at 12:01 PM | Unregistered CommenterJames P

I could be wrong, but didn't Delingpole first notice and then christen Ms Shuckburgh?

May 23, 2011 at 12:28 PM | Unregistered CommenterJustice4Rinka

Dr Shuckburgh
The uptake of CO2 (by various mechanisms) by the earth system is estimated to be greater by upto a factor of 16 in a cooling phase than its release in a warming phase.

I am referring here to climate sensitivity of the global carbon cycle (termed γ): i.e., how much atmospheric CO2 increase does each C rise of temperature entail, and how much a drop of every degree C reduce CO2 by.

In other words, once the temperature starts dropping, atmpospheric CO2 drops much more rapidly (than the rise that would occur with every C rise of temperature). This is from Frank et al 2010 Nature.

May 23, 2011 at 12:48 PM | Unregistered CommenterShub

Emily - Thanks for the quick reply.

Doesn't the ice core data show that CO2 levels lag temperature by 800 years?

And just to be clear can you confirm that when you say "concentrations of atmospheric carbon dioxide decreased by about 30% in the transition from warm interglacial to cold glacial periods" you actually mean that CO2 levels fell from about 400ppm to about 250ppm? If so this equates to change of atmospheric concentration from 0.04% to 0.025% - a 30% change it may be but it is 30% of feck all. If you are suggesting that it was such a relatively minor variation in atmospheric concentrations of CO2 which drives the Earth from glacial to inter-glacial, does this not imply that CO2 has a staggeringly high climate sensitivity - much higher than even the IPCC modellers contend? As CO2 is now back up to 390ppm shouldn't we now be experiencing Mediterranean temperatures here in Scotland?

A relatively small change (possibly only 2 or 3%) in the average cloud cover over the tropics and mid latitudes allows in much more sunlight to warm the land and oceans and decreases albedo, and is enough to explain all the historic variability in the Earth's climate. Svensmark and Shariv have come up with a very plausible mechanism to explain how GCR could influence cloud cover.

Given Beer-Lambert Law, I maintain that adding or removing an extra two CO2 molecules for every 10,000 other molecules in the atmosphere isn't going to make a jot of difference to global average temperatures (not when CO2 levels are above 250ppm anyway). It is clear that H20 is the planet's refrigerant (and key greenhouse gas). If you are so convinced CO2 is the key player can you please cite some observational evidence for this?

May 23, 2011 at 12:50 PM | Unregistered Commenterlapogus

Hi James,

The aspect my group is trying to understand is the ocean circulation. If that changes then it can change the distribution of carbon dioxide and heat in the ocean and the exchange with the atmosphere. That was the point I was originally trying to make. It is actually fascinating to try to understand how small-scale mixing can drive a global-scale overturning circulation. In this area we are still on a voyage of discovery, hence the crucial need for going to sea and taking measurements.


May 23, 2011 at 12:50 PM | Unregistered CommenterEmily Shuckburgh


With regard to the carbon dioxide, ice core, ice ages, etc comments above, I have asked my colleague Eric Wolff (yes, Josh is on the case of an Antarctic Wolff cartoon) to respond because it is his area of expertise. He'll be posting some comments later today.


May 23, 2011 at 3:02 PM | Unregistered CommenterEmily Shuckburgh

Arctic Fox turns Arctic Chicken, sends Arctic wolf to huff and puff at the three little Arctic pigs in their Arctic Igloo!

Josh is going to be very busy ^.^

May 23, 2011 at 3:20 PM | Unregistered CommenterFrosty

Be sensible Frosty.

May 23, 2011 at 3:41 PM | Unregistered CommenterBBD


I must admit that, like Shub, I am curious about the value implied for climate sensitivity to CO2.

Do I understand correctly:

- the lagged climate response Milankovitch forcing is due to to oceanic outgassing of CO2

- the outgassing is modulated by changes in overturning circulation (Southern Ocean)

- this is, for example, the mechanism behind the delayed onset of the Holocene Thermal Maximum?

The temperature changes between ice ages and warm inter-glacial periods cannot be explained solely by changes in incoming radiation by changes in solar radiation from orbital variations.
How sure are we of this? (eg contra Roe, GRL, 2006)

May 23, 2011 at 4:00 PM | Unregistered CommenterBBD


Sorry, I should also have asked: does Lacis et al. (2010) play a part in the thinking here?

May 23, 2011 at 4:10 PM | Unregistered CommenterBBD

"the crucial need for going to sea and taking measurements"

Can't argue with that, Emily. Thank you for taking the trouble to reply - I'm sure most of us here are eagerly awaiting the results of your voyage!

May 23, 2011 at 6:50 PM | Unregistered CommenterJames P

Never mind the CO2, DIMES is doing some interesting things. Masterfully understated comment about one aspect in their outreach document:

They plan to follow the tracer patch for at least the next three years. The Antarctic Circumpolar Current (ACC) will carry it eastward through Drake Passage, but it will behave somewhat as cream does as it is stirred into coffee, not like a neat package moving in a straight line. It’s precisely this messiness that interests the scientists..

So take 40kg of tracer, add to a very very large coffee cup and then try to find it after it's been rather diluted.. which is pretty neat.

I'm still curious about funding though. Am I right in thinking this is initial work to test the basics? The map got me thinking about how easy it would be to string cables across the passage and do some acoustic tomography mapping. That would cost, but potentially provide longer term data.

May 23, 2011 at 6:56 PM | Unregistered CommenterAtomic Hairdryer

Emily has asked me to make a post, because a few comments in this thread have moved onto discussion of glacial-interglacial CO2 changes, derived from ice core measurements. As Emily indicated, ice cores are my primary scientific expertise. I’ll try to answer most of the points on this topic that I can see so far, but not necessarily in the order they were posted.

Firstly to describe what happens: CO2 in the 4 interglacials previous to the current one (ie over the last 450000 years) reached levels around 280-300 ppmv. In glacial maxima the concentration went as low as 180 ppmv. So the first point for lapogus is that the current concentration of 390 ppmv is not the baseline, but is a highly unusual outlier. Then you suggested that because the concentration is low it cannot affect climate. The major constituents of the atmosphere, nitrogen and oxygen, are simply not significant absorbers of infrared radiation. It is only when we reach triatomic molecules such as H2O, CO2 and polyatomic molecules like CH4 that we find efficient absorbers of infrared. If one observes the Earth from above, one can easily see from the infrared spectrum that these minor constituents have indeed absorbed significant amounts of radiation at their absorbing wavelengths. It is then relatively simple to calculate that, without any feedbacks, doubling CO2 in the atmosphere leads to a roughly 1 degree warming. The fact that the many CO2 molecules in an atmospheric column are surrounded by even more of the non-absorbing nitrogen molecules does not affect this.

From glacial maximum to full interglacial conditions, Antarctica warmed by about 10 degrees C, and the global average was probably about 5 degrees. As Emily says, it appears as if the glacial-interglacial cycles were paced by the variations in sunlight at different latitudes and seasons that were in turn driven by changing orbit and tilt of the Earth. To get the amplitude of climate change though, one definitely needs amplifiers. Palaeoclimate observations of changes in ice cover, CO2 concentration and precipitation (hence water vapour) along with very well-known physics tells us that at least three amplifiers (two slow and one fast) must have been involved in each warming (and correspondingly in each cooling): firstly the decreased (on warming) albedo (reflectivity) of the land and ocean surface (white sea ice and land ice reflect much more radiation than dark ocean and vegetation); secondly the increase of CO2 concentration, and thirdly the fast feedback of an increased concentration of water vapour. Without any of these, it seems impossible to reach the temperature change that is observed. Svensmark’s idea (as yet far more tenuous than the well-known physics of infrared absorption by “greenhouse” gases) that increased cosmic rays may influence climate variability through changes in cloudiness is interesting and worth pursuing. However I doubt that Svensmark has ever suggested that there were major changes in cosmic rays at the pacing of the glacial cycles: and indeed the 10Be flux in ice cores shows us that there were not.

The lag out of the glacial period is much misunderstood, and it is good if people actually look at the data (see Fig 4 of On the way out of a glacial period, both (Antarctic) temperature and CO2 rise slowly over a period of about 5000 years. For most of this period, they rise together, just as you’d expect with a feedback: the temperature causes extra CO2 to be released from the ocean, the extra CO2 causes a further warming. The temperature appears to start to rise before the CO2, by 800 years according to Monnin et al. What that means is that there is 800 years in which Antarctic temperature warmed by about half a degree, and then the carbon cycle started to respond. For the remainder of the 5000 years, both CO2 and temperature rises in parallel. This only shows us what we already knew, that the CO2 did not initiate the glacial-interglacial changes, only amplified them. This in no way negates the idea that a rise in CO2 CAN initiate climate change.

Finally, Shub suggested that the sensitivity of CO2 to cooling is much stronger than its sensitivity to warming. I simply don’t know what you are referring to there; certainly not Frank et al who you cited. Please clarify if you still need this issue addressing.
I hope this helps.

May 23, 2011 at 7:19 PM | Unregistered CommenterEric Wolff

The science is beyond me, but the exchanges between the Antarctic Fox and Wolf and the commenters on this blog seems to me exactly how such conversations should be conducted. Thank you all for the civility and thanks to the Bishop for the post.

May 23, 2011 at 8:00 PM | Unregistered CommenterMessenger

I agree. Thank you all for your interest in the DIMES project - I will certainly update you when we have analysed the data we collected.

Best wishes,


May 23, 2011 at 8:14 PM | Unregistered CommenterEmily Shuckburgh

I just love this blog. Thanks for engaging, Emily and Eric!

"firstly the decreased (on warming) albedo (reflectivity) of the land and ocean surface (white sea ice and land ice reflect much more radiation than dark ocean and vegetation); secondly the increase of CO2 concentration, and thirdly the fast feedback of an increased concentration of water vapour. Without any of these, it seems impossible to reach the temperature change that is observed."

Eric, it still seems that the general explanation is that "CO2 must have strong positive feedback because we can't think of anything else to have caused the temperature change" rather than some more direct evidence based science. It that a fair description?

May 23, 2011 at 8:37 PM | Unregistered Commenterpax

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