Guest Post by Willis Eschenbach
Anthony has pointed out a new paper by McKinley et al. regarding the carbon sinks of the oceans (preprint available here , supplementary online information here). The oceans absorb and sequester carbon from the atmosphere. As usual in this world of “science by press release”, the paper has already been picked up and circulated around the planet. CNN says:
The ability of oceans to soak up atmospheric carbon dioxide is being hampered by climate change, according to a new scientific study.
A fresh analysis of existing observational data taken from locations across the North Atlantic Ocean recorded over a period of almost three decades (1981-2009) has revealed that global warming is having a negative impact on one of nature’s most important carbon sinks.
“Warming in the past four to five years has started to reduce the amount of carbon that large areas of the (North Atlantic) Ocean is picking up,” said Galen McKinley, lead author and assistant professor of atmospheric and oceanic sciences at the University of Wisconsin-Madison.
Figure 1. An estimate of the net CO2 flux into and out of the oceans, from Takahashi 1999. McKinley et al. say that the flux into the ocean is slowing.
The lead author says in the press release that things are getting worse … but since it is nearly guaranteed that the paper says something different from the spin the press release authors put on it, what does their paper actually say?
The first oddity about the paper is that they are discussing changes in the partial pressure of CO2 in the ocean (written as “pCO2”). But they’re not actually measuring the pCO2. They are calculating it from the dissolved inorganic carbon (DIC), alkalinity (ALK), sea surface salinity (SSS) and sea surface temperature (SST). Now, this is a standard scientific procedure used to estimate unknown variables in the oceanic carbon balance. But while it is generally a good estimate, it is still an estimate. It is calculated using an empirical formula, that is to say, a formula which is not based on physical first-principles. Instead, an empirical formula uses observation-derived parameters in an iterative goal-seeking algorithm to solve a complex formula.
As you might imagine, different authors use different parameters in the equation. There is a good overview of the function as it is used in the R computer language located in the “seacarb” package. If we take a look at the function “carb” in that package we see that in addition to the pCO2 depending on the variables they have measured, it is also affected by the levels of phosphate and silicate (which apparently the authors have not included). They give details of the different possible choices of values for the various parameters. From the description of the function “carb”:
The Lueker et al. (2000) constants for K1 and K2, the Perez and Fraga (1987) constant for Kf and the Dickson (1990) constant for Ks are recommended by Dickson et al. (2007). It is, however, critical to consider that each formulation is only valid for specific ranges of temperature and salinity:
For K1 and K2:
• Roy et al. (1993): S ranging between 0 and 45 and T ranging between 0 and 45oC.
• Lueker et al. (2000): S ranging between 19 and 43 and T ranging between 2 and 35oC.
• Millero et al. (2006): S ranging between 0.1 and 50 and T ranging between 1 and 50oC.
• Millero (2010): S ranging between 1 and 50 and T ranging between 0 and 50oC.
Millero (2010) provides a K1 and K2 formulation for the seawater, total and free pH scales. Therefore, when this method is used and if P=0, K1 and K2 are computed with the formulation corresponding to the pH scale given in the flag “pHscale”.
For Kh:
• Perez and Fraga (1987): S ranging between 10 and 40 and T ranging between 9 and 33oC.
• Dickson and Riley (1979 in Dickson and Goyet, 1994): S ranging between 0 and 45 and T ranging between 0 and 45oC.
For Ks:
• Dickson (1990): S ranging between 5 and 45 and T ranging between 0 and 45oC. • Khoo et al. (1977): S ranging between 20 and 45 and T ranging between 5 and 40oC.
As you might imagine, results depend on the choice of parameters.
In addition, McKinley et al. do not have observations for all input variables for all periods. Their study says:
For 2001-2007, ALK [total alkalinity] was directly measured. For 1993-1997, ALK was estimated from the ALK-SSS [sea surface salinity] relationship derived from 2001-2006 data (ALK = 43.857 * SSS + 773.8).
I bring these issues with the carbon calculations up for a simple reason—errors. Obviously, when you are estimating a critical value (pCO2) using an empirical formula with a choice of parameter values, with missing observations, and not including all of the known variables, you will get errors. How big will the errors be? It depends on the exact location being studied, the values of the various input variables, and your choice of parameters. As a result you will have to “ground-truth” the formula for the various biomes of interest. “Ground-truthing” is the process of comparing your calculations to actual measurements in the physical locations of interest. Once you have done that you can use the measured error, as well as any bias, in determining the significance of the results.
There is a discussion here of the oceanic carbon calculations, and some graphic examples of both calculated and measured pH, showing the size of the errors in another similar study. See in particular their Figure 1, which shows that errors in the calculation of pH, while generally moderate in size, are pervasive, unpredictable, and at times large.
Whatever the size of the errors resulting from the oceanic carbon calculations, they need to measured against observations in the regions studied, and then described and accounted for in the study. As far as I can tell the authors have not done either of these things.
The second oddity about the paper also involves errors. They have not (as far as I can tell) adjusted their error values for autocorrelation. Autocorrelation is a measure of how much tomorrow’s temperature is dependent on today’s temperature. As you know, warmer days are generally followed by warmer days, and colder by colder. It is unusual to see an ice-cold day in between two warm days.
Since when it is warmer it tends to stay warmer, and when it is cooler it tends to stay cooler (temperature records show positive autocorrelation), this means that the swings in the temperature will be larger and longer than we would find in purely random data. As a result, we need to adjust the calculations depending on the level of autocorrelation, in order to decide if the trends (or the difference between the trends) is statistically significant or not. As far as I can tell, the authors have not adjusted for autocorrelation.
The third oddity is one that I really don’t understand. The authors use a standard method (a “Student’s T-test”) to determine the uncertainty in the two trends, the trend in the pCO2 in the ocean, and the trend of CO2 in the atmosphere.
Then they use another test to determine if two trends (oceanic and atmospheric) are different. From their paper, here’s their description of the test, which contains the reason for the title of this piece, “Lowering the Bar”.
Figure 2. The description of the significance test used in to determine if trends are significantly different or not.
The “p-value” that the authors discuss is a measure of how unusual a result is. For example, if we flip a coin five times and it comes up heads every time, does that mean that the coin is weighted to come up heads? Or is it just a random outcome? The p-value gives us the odds that it was just a random outcome.
In the hard sciences, people like to see a p-value that is less than 0.001 (written as “p<0.001”). This means that there is only one chance in a thousand (1 / 0.001) that it is just a random outcome.
In climate science, the bar is generally lower. A result with a p-value less than 0.05 is regarded as being statistically significant. A p-value of 0.05 means that there is one chance in twenty (1 / 0.05) that whatever you are looking at is just a random fluctuation.
(As a brief aside regarding the use of p=0.05 as significant , consider that a scientist may look at a variety of datasets trying to find the “fingerprint” of a hypothesized mechanism such as anthropogenic global warming. Suppose on the sixth dataset he examines, he finds an effect which is significant at p=0.05. What are the odds that this is a chance occurrence? The odds are not one in twenty, because he’s looked at several datasets, so his odds of hitting a random jackpot have increased. In this case, if he finds it on the sixth try, the odds are already one in four that it’s just random chance, not a real phenomenon. End of digression.)
Now, if I understand what McKinley et al. are saying above (which I may not, all corrections welcome), they are saying that in their study a p-value less than 0.317 is considered statistically significant. But at that level of p-value, the odds of what is observed being merely a random phenomenon, something occurring by pure chance, is about one in three. One in three? … what am I missing here? Is that really what they are claiming? I’ve read the paragraph backwards and forwards, and that’s how I understand it. And if that’s the case, they’ve lowered the bar all the way to the ground.
In mystery,
w.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Mike Jonas says:
July 12, 2011 at 3:09 am
____________________________
It seems the temperature point is probably correct. Then would the authors be assuming a homogeneous ocean, like my old favorite “assuming a spherical cow…”? What happens if the temperature in some locations increases such that biological mechanisms of increasing alkalinity is reduced. That is, the temperature exceeds an optimum temperature. Nearby locations that were below the optimum temperature would also warm and then be at the optimum.
Is there an optimum temperature that is likely? Or with the achievable temperatures in the ocean, would not warmer actually tend to activate the biological processes needed to capture CO2 and increase alkalinity (e.g. nitrogen fixation)? There is quite a range of temperatures in the oceans. Although temperatures seem not to exceed the low 30s °C (http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/images/monsstv2.png), shallow locations might be significantly warmer. If we are only considering whether CO2 is absorbed or not, then warmer might be better in terms of biological productivity. However, population distributions of the species performing these functions might shift considerably as conditions change.
It is strange that humans must manage every aspect of the planet on the one hand, and blame ourselves for interference on the other. Let nature adjust itself. Life finds a way to survive. There isn’t anything we can do that would make a difference anyway. I find it amusing how people propose solutions based on small-scale experiments or models, and don’t bother to calculate what would be required to actually do what they propose on a scale that would matter. For example adding iron to fertilize the ocean. A really silly idea when you look at the numbers, see my comment here: http://wattsupwiththat.com/2011/02/02/ocean-fertilization-to-affect-climate-have-a-low-chance-of-success/
Having said that, a natural source of iron, that is dust, might influence ocean chemistry. A paper discussing a model (ick) of dust changes and possible effects on the ocean is here: http://adsabs.harvard.edu/full/2006TellB..58..560M. Although the authors describe a “positive feedback” for climate change, there are some interesting points made. One is increasing vegetation covering the land a result of CO2 fertilization reduces the dust reaching the ocean. As a result of decreased dust depostion the oceans outgas CO2. Well then, the observed increase in CO2 ppmv might not be due to combustion of fossil fuel after all. The paper also reinforces the importance of nitrogen fixation on CO2 uptake, that is, increasing alkalinity.
What’s the take-home lesson? Ocean chemistry is not simple. Multiple game changers can invalidate simple models. The ability of biota to respond to changing conditions is one factor that can’t be swept under the rug in any realistic description of ocean processes. Once you realize that, models become recognizable as toys. They are interesting and useful for understanding interactions, but these very limited models should not guide policy making.
DirkH says:
July 12, 2011 at 11:39 am
If the 12month difference in CO2 concentrations correlates strongly with tropospheric temperatures, as has been shown, this can mean that the 12month difference in our CO2 ouput directly drives temperatures, which would contradict AGW theory, or it could mean that temperatures drive CO2 increase/decrease; rendering it completely irrelevant how much or how little CO2 we emit.
One need to be careful: temperature drives the variability in CO increase rate, doesn’t drive the increase itself (except for maybe 8 ppmv since the LIA), which is at about 55% of the human emissions over the past 50 years (and beyond).
The assumption of such work is that of a process feedback.
And that is just plain wrong.
If the SST’s rise, the ocean sinks less CO2, which warms the planet and SST.
An endless trend.
But, CO2 warming is logarithmic, so the feedback is not linear, but subject to the law of diminshing returns.
Another problem with the paper:
“Warming in the past four to five years has started to reduce the amount of carbon that large areas of the (North Atlantic) Ocean is picking up,” said Galen McKinley, lead author and assistant professor of atmospheric and oceanic sciences at the University of Wisconsin-Madison.
Wrong again.
The process began not four or five years ago, but has been going on since the bottom of the Little Ice Age. At whatever rate CO2 warms at the level it was when temps began to rise, the logarithmic decrease curve was well underway. So warming oceans will not absorb as much CO2, but since CO2 levels were not zero 4 to 5 years ago, the ability of the oceans to absorb CO2 is even less affected by warming than 150 years ago, which was likewise not zero.
Making a Mountain out of a moehill.
Errata: The assumption of such work is that of a process feedback.
Shour read: The assumption of such work is that of a process feedback endless loop.
Dave Springer says:
July 12, 2011 at 6:41 am
CO2 level in the atmosphere has been dangerously low since the beginning of the ice age several million years ago. At 200ppm plants are being starved for it. Worrrying about it a gigantic waste of time. The earth is a huge lush garden at least up to 2000ppm. Rarely in deep time does it get as low as it is today. Low CO2 is a harbinger of starvation and death for the biosphere. We need more of it not less.
Perhaps Mother Gaia with her great wisdom noticed that natural processes of carbon sequestration were proceeding toward a “tipping point” where all the life she struggles to maintain on the planet would be driven into a “death spiral” by carbon starvation and decide to support the rise of humankind because we are the only species capable of developing the physical and intellectual talents to seek out all that sequestered carbon and release it back into the cycle to restore the proper life supporting balance of the planet. All those tree hugging Gaia worshippers out there trying to reduce their carbon footprint to zero, may actually be acting to foil Mom’s clever plan. That could explain the present spate of earthquakes, volcanoes, and other natural nastiness we are experiencing. Mom is just giving us a good smack up side the head to tell us to snap out of it.
semi-sarc/off
Fred H. Haynie says:
July 12, 2011 at 7:11 am
steveta_uk asks: “If this work was correct, wouldn’t the atmospheric CO2 levels show a signal that correlates with global SST? Has anyone looked?“.
A lot of people have done this including myself. There is little question that the Arctic ocean is the major sink for atmospheric CO2 and the strength of that sink is a function of ocean chemistry and temperature. In correlation, the question is which comes first (driving force),” the chicken or the egg” and what is natural change and how much does man’s contribution of CO2 to the atmosphere contribute to the warming of the Arctic ocean. I submit that CAGW is statistically insignificant. http://www.kidswincom.net/climate.pdf and http://www.kidswincom.net/CO2OLR.pdf.
OK – Let us continue just a bit further: Geographically, CO2 is NOT well-mixed in the atmosphere – showing very strong peaks where there is no plant life (Gobi Desert, Saudi and Arabian Deserts westward through the Sahara Desert, Kalahari and central Australian deserts, etc.) and very strong troughs where plant life exceeds “normal” over large areas (Eastern US pine and hardwood forests, Amazon and Congo jungles, etc.)
So, where do the prevailing winds blow across these “natural” – but un-plotted and un-analyzed!!! highs and lows of natural CO2 distribution? How did the “researchers” account for the sinks and sources of the CO2 they are supposedly plotting (er, photo-shopping from modelling) when they have not plotted so much of the world’s known variations in CO2 levels due to plant life?
What have they correlated between massive differences in ocean plant life – not discussed apparently – compared to a temperature difference of ONLY 0.25 degree from “normal” temperatures?
DesertYote said @ur momisugly July 12, 2011 at 8:57 am
“I guess I am just too stupid. I don’t understand what the authors work either.”
It’s not meant to be understood. It’s meant to be believed
Alkalinity, total hardness, carbonate hardness, pH, carbon dioxide, the carbonate-bicarbonate system, and calcium carbonate are all part of the buffering system present in seawater.
Seawater contains carbon dioxide gas. When dissoved in water, carbon dioxide reacts with the hydrogen of water to form a weak acid, carbonic acid (H2CO3). If excess carbon dixoide is in the water, carbonic acid levels increase and pH levels drop. If too much carbon dioxide is taken from the water, carbonic acid decreases and pH levels quickly rise. Addition or deletion of carbon dioxide beyond atmospheric equilibrium temporarily changes pH but does not change the alkalinity (carbonate composition) of the water. Carbonic acid forms negatively charged carbonate (CO3 to 2nd -) and bicarbonate (HCO3-) ions. Carbonate in turn joins with calcium to form calcium carbonate (CaCO3). The chemical reactions that form bicarbonate, carbonate, and calcium carbonate are equilibrium reactions; that is they can go back and forth depending on conditions such as increase or decrease of carbon dioxide, pressure, and temperature.
Under normal physical and biological conditions, the carbonate-bicarbonate ions act as a bank that automatically takes up excess carbonic or other acids, or forms more carbonic acid if carbon dioxide is lost. This is the buffer system that maintains the normal pH of seawater at about 8.2. Bicarbonate is most important in the normal pH range of seawater. Calcium is an important element present in seawater and is part of this system. Calcium is important for building coral skeletons, mollusk shells, and algal support, and has numerous other biological uses as well. As calcium carbonate is removed from seawater by chemical and biological processes (mostely utilized in the shells of tiny planktonic animals), more bicarbonate forms from carbonate, more carbon dioxide is assimilated into the buffer system, and pH remains constant. The carbonate-bicarbonate buffer system equilibrates back and forth and pH stays relatively constant.
The only way to “acidify” the oceans is to deplete the Calcium, but since Calcium is the fifth most prominent element on earth, that is unlikely. Calcium Carbonate is not very soluble in water, so decreasing the pH (increasing CO2) of seawater will result in the increased precipitation CaCO3, thereby raising the pH.
@Nick Stokes: “I believe most of their pCO2 data is directly measured, by gas equilibration. That is , by actually measuring pCO2 above the sea water. That’s as direct as you can get.”
The problem with that is that the rate of CO2 flux at the ocean surface is driven by the difference between pCO2 in the ocean surface and pCO2 just above it. So if your paper is addressing rate of CO2 flux, you can’t use one pCO2 for the other. See @ferdinand meeus Engelbeen below. [There are other factors, such as wind speed].
@ferdinand meeus Engelbeen: “The average pCO2 difference between atmosphere and oceans is about 7 microatm, according to Feely”
Using data from Takahashi
http://www.ldeo.columbia.edu/res/pi/CO2/carbondioxide/pages/air_sea_flux_1995.html
http://www.ldeo.columbia.edu/res/pi/CO2/carbondioxide/pages/air_sea_flux_2000.html
I calculate it at just over 1 (weighted by area, in both 1995 and 2000). In 1995 it ranged from about -200 in the Arabian sea to about +180 between Svalbard and Greenland. Given the high range, the way the average is calculated is probably rather significant.
@Crispin in Waterloo: “If the Arctic Ocean is cold and absorbing CO2 at a faster rate than oceans in the warmer southerly climes, where does it go?”
I understand that it sinks into the deep, and is carted off by the Thermohaline Circulation. Several hundred years later, it gets back to the surface and can release the CO2 into the atmosphere again.
@Hoser: “Ocean chemistry is not simple. … Once you realize that, models become recognizable as toys.”
Nicely put.
Dave Wendt says (July 12, 2011 at 12:26 pm): “Perhaps Mother Gaia with her great wisdom…”
Personally I think Gaia just got tired of all those nasty asteroid impacts and tried to develop a defense system (us).
Unfortunately she got Al Gore instead.
Epic FAIL.
Mike Jonas,
The direct pCO2 method is described here. It is done in flasks. Yes, in the sea there is disequilibrium, but that is fixed in the measurement process.
RobR,
That’s a nice summary of the buffering process. But it goes wrong right at the end.
“Calcium Carbonate is not very soluble in water, so decreasing the pH (increasing CO2) of seawater will result in the increased precipitation CaCO3, thereby raising the pH.”
No, as you’ve said, there is a chain of reaction. If you add CO2, down the chain free carbonate is converted to bicarb. Then CaCO3, tends to dissolve, not precipitate. That’s the problem that shell-building organisms have with increasing CO2.
As you say, the pH is buffered. But what achieves that is the conversion of carb to bicarb (mainly) and bicarb to carbonic acid as CO2 is added. And at the end of the chain, adding dissolved carbonate by convertinging CaCO3, which is actually generally present in supersaturated concentrations.
Does the ocean become more acidic when it warms and gives off CO2? Yes it does, until a new equilibrium is reached. This is illustrated well with the Bjerrum Plot for the carbonate system in sea water. It can also easily understood from
more CO2 => water more acidic => more CO2 dissolved, in reverse.
Now that the oceans are cooling, we can expect a reversal in the trend of CO2, but the ocean’s inertia is large so it won’t be noticeable immediately.
The relationship between temperature and CO2 has been demonstrated by Lance Endersby and reproduced on the Seafriends web site http://www.seafriends.org.nz/issues/global/acid2.htm which deals with the CO2 chemistry in water. He arrives at 150ppm per degree C, more than enough to explain all ‘anthropogenic’ CO2 since the industrial age, all coming from the sea.
There are many compelling reasons why CO2 cannot have an influence on climate, regardless of the views by many. Explained in: http://www.seafriends.org.nz/issues/global/climate.htm . Important educational reading!
@Nick Stokes – Thanks for posting the link. What I was questioning was your earlier “measuring pCO2 above the sea water“, when they should be measuring pCO2 in the seawater. I see they aren’t measuring pCO2 above the sea water in situ – which is what your original statement sounded like – but in the lab. So there’s no problem (well not that one anyway).
“…what does their paper actually say?”
Not “We’re doomed”?
RobR is pretty much on the mark. However, in addition to the change on CO2 solubility as a function of temperature, there are very complex interactions with salt concentration. In complex CO2 buffering systems, especially with mixed mono/divalent cations, you cannot estimate the actual pCO2 with any sort of precision.
The paper cited by Nick Stokes will work, as long as they measured both pCO2 and total acidifiable CO2.
The first sensible Gaian hypothesis I’ve ever read.
😉
I hope her aim is good when she “takes out” her opponents. The potential for collateral casualties is immense.
About “problems for shell building organisms” … not unless they’re ancestor-worshipers. The bicarbs aid in new shell-building, and in dissolving dead shells. I.e., they accelerate the cycling. Which equals more shellfish, more life. Bigger corals, more migration of corals, faster reef-building, more clams and mollusks, etc. All the things that actually show in the geo-paleo-record.
Nick Stokes says:
July 12, 2011 at 5:23 pm
Limestone
“Nick Stokes says:
July 12, 2011 at 5:23 pm
RobR,
That’s a nice summary of the buffering process. But it goes wrong right at the end.
“Calcium Carbonate is not very soluble in water, so decreasing the pH (increasing CO2) of seawater will result in the increased precipitation CaCO3, thereby raising the pH.”
No, as you’ve said, there is a chain of reaction. If you add CO2, down the chain free carbonate is converted to bicarb. Then CaCO3, tends to dissolve, not precipitate. That’s the problem that shell-building organisms have with increasing CO2.
=====
That sounds plausible enough, but is it consistent with the formation of “cap carbonate” deposits when oceans warm after severe glaciations? For those who have never heard of them, cap carbonates are sometimes quite thick deposits of inorganically deposited limestone (Ca2CO3) or dolomite (CaMg(CO3)2). They are, for example, found worldwide in sedimentary sequences from the late Proterozoic — e.g. the 300 meter thick Noonday Dolomite in the Southwestern US.
That suggests to me that the state equation (ignoring Mg++ which is sort of interchangeable with Ca++) might be something like:
CO2 + H2O + Ca++ H2CO3 +Ca++ H+ + HCO3- + Ca++ 2H+ + CO3– + Ca++ 2H+ + Ca2CO3
And that warming the ocean drives the equation to the right, simultaneously making the ocean more acidic and precipitating Ca2CO3. Note that this probably only works if one decreases pH (increases acidity) by warming the ocean, NOT if one simply pours in hydrochloric acid or some other acid.
This is really complex beyond my ability to understand even though my much younger self received a degree in chemistry from an otherwise reputable university. Whatever the actual mechanism, it would seem to have to be consistent with precipitating lots of CaCO3 when cold oceans are warmed.
I see that WordPress has thoughtfully removed the double ended arrows from the state equation I just posted which was already quite incomprehensible — artificial stupidity in action … It probably treated them as html comments which they did vaguely resemble. Let’s try again using === as a code for a double ended arrow (and removing an extraneous 2 from CaCO3).
CO2 + H2O + Ca++ === H2CO3 +Ca++ === H+ + HCO3- + Ca++ === 2H+ + CO3– + Ca++ === 2H+ + CaCO3
Nick Stokes says:
July 12, 2011 at 3:45 am
We do not disagree, Nick. My point remains. As I said:
Recall also that this was only one of three problems with the error estimation in the study. The other two were lack of adjustment for autocorrelation, and an absurdly low bar for claiming results were significant. Between the three, the study is meaningless.
Why do you think that they have picked such a ludicrously high p-value, 0.31, as their threshold for significance? Would they do that if their results were significant at the usual level?
The real joke is that at a p-value of 0.31, when you look at three areas (say SP-SS, ST-SS, and ST-PS as in their study) you already have better than 50/50 chance of finding a “significant” result by nothing but pure, random chance.
The odds of NOT getting a false result are (one minus p-value) to the Nth power, where N is the number of areas investigated. This gives us:
(1 – 0.3) =.7 ^ 3 = 0.34
That equation’s result gives the odds of NOT getting a bogus result by chance. The odds of it happening by chance are one minus that value, so McKinley et al. have about a sixty-five percent chance of spurious “significance” in their study … I’d take that bet.
Thanks,
w.
Mike Jonas says:
July 12, 2011 at 3:15 am
steveta_uk asks: “If this work was correct, wouldn’t the atmospheric CO2 levels show a signal that correlates with global SST? Has anyone looked?“.
I didn’t have SSTs available when I graphed this data in 2009, so I used satellite global lower troposphere temperature. Yes there is a connection.
http://members.westnet.com.au/jonas1/deltaCO2vsTemp.JPG
If you treat both the co2 and SST datasets the same way (taking the rate of change) and look at subsets of the curve you can see changes in the rate-of-change of co2 always lag the changes in the rate-of-change of sea surface temp by 6-9 months.
http://tallbloke.wordpress.com/2011/06/26/which-causes-which-out-of-atmospheric-temperature-and-co2-content/
Cause precedes effect.
Willis:
Thankyou for this but, with respect, your comment in this thread at July 12, 2011 at 11:26 pm
is all that matters: everything else is mere detail.
The paper by McKinley et al says;
“Here, we study trends in observed surface ocean partial pressure of CO2 (pCO2) in three gyre-scale biomes of the North Atlantic, considering decadal to multidecadal timescales between 1981 and 2009.”
Simply, they analysed data from three regions.
And the paper also says;
“Convergence of the oceanic pCO2 trends to the atmospheric pCO2 trend for timeseries longer than 25 years is a robust feature, and the fact that temperature trends are largely indistinguishable from zero suggests that carbon accumulation is the primary driver of these trends. However, a long-term waning influence of pCO2-T is not entirely clear, given that timeseries starting in 1981 continue to be influenced by warming; and thus, multi-decadal climate variability may still be influencing subpolar biome pCO2 trends12,13,25 over the full period for which data is available. In the seasonally stratified subtropical biome (ST-SS, Figure 2b) oceanic pCO2 trends are also sensitive to the choice of years for short timeseries. Beyond 25 years, oceanic pCO2 trends are, with only one exception, indistinguishable from atmospheric pCO2 trends.”
In other words, they discerned no affect of change to ocean take-up of CO2 from the air in any of the three regions when they analysed periods longer than 25 years (i.e. they find an expected relationship between changes in oceanic CO2 partial pressure and atmospheric CO2 partial pressure in each case).
But they did discern an apparent effect of reduced ocean take-up of CO2 from the air in ONE of the three regions when they analysed the period from 1981 to 2005.
This apparent effect was significant at one-sigma: i.e. the apparent significance of the effect had a chance of being wrong one-in-three times.
SUMMARISING
1.
McKinley et al conducted six studies: i.e. three for longer than 25 years and three of 25 years.
2.
They used a definition of ‘significance’ that is statistically expected to provide a false indication of ‘significance’ one-in-three’ times.
3.
So, their results could be expected to provide one or two indications of ‘significance’ that are wrong.
4.
Their results provided only one indication of ‘significance’.
5.
Hence, the paper from McKinley et al provides no indication of anything except that it reports they failed to discern a change to ocean take-up of CO2 from the air.
CONCLUSION
The paper from McKinley et al is merely another example of pal review.
Richard
Willis,
I think they shouldn’t have used the word significance. They aren’t doing a regular significance test, AFAICS. They are using 1 sd as a unit and plotting colored graphs like Fig 1. And they describe a separation of <1 sd as “indistinguishable”.
This is a common use of an sd. It’s how measurement error is often expressed (+- 1 sd). It’s what we call sampling error in polling.
I think they probably should have allowed for autocorrelation, but we don’t know how much there was. I’m familiar with patterns of surface temperature residuals, but not with CO2 residuals.