Steve Fitzpatrick writes in with a short essay:
On May 11 you reposted a blog from Dr. Roy Spencer, where he suggests that much of the increase in atmospheric CO2 could be due to warming of the oceans, and where he presents a few graphs that he claims are consistent with ocean surface temperature change contributing more than 80% of the measure increase in CO2 since 1958. Dr. Spencer’s suggestion is contradicted by many published studies of absorption of CO2 by the ocean, with some studies dating from the early 1960’s, long before “global warming” was a political issue. In this post I offer a simple model that shows why net absorption of CO2 by the ocean is most likely the main ocean effect.
If the rise in CO2 is being driven by human emissions, then the year-on-year increase in atmospheric CO2 ought to be a function of the rate of release of CO2, less any increase in the rate of removal of CO2 by increased plant growth and by absorption and chemical neutralization of CO2 by the ocean. Both ocean absorption and plant growth rates should increase with increased CO2 concentration in the atmosphere. To simplify things, I focus here only on ocean absorption.
On the other hand, surface temperature changes ought to have a relatively rapid effect, because the surface of the ocean is in contact with the atmosphere and so can quickly absorb or desorb CO2 as the water temperature changes. In fact, the ocean surface continuously absorbs CO2 where the temperature is falling, mostly at high latitudes, and emits CO2 where the water is warming, mostly at lower latitudes. Cold upwelling water from the deep ocean warms at the surface and desorbs CO2, while very cold water at high latitudes absorbs CO2 before it falls to the deep ocean. An increase in average ocean surface temperature will cause more CO2 to be emitted from surface water, but this effect is limited to a very small volume fraction of the ocean. Effects due to rapid temperature changes (annual time scale and less) are limited to a relatively thin layer, while the gradual absorption/neutralization process takes place at a rate controlled by ocean circulation and replacement of the surface water with upwelling (and “very old”) deep ocean water.
Any change in sea surface temperature should add to or subtract from the atmosphere’s CO2.
Annual change = (Annual emissions) – K1 * (CO2 – 285) + K2 * (delta SST)
Where “CO2” is the atmospheric concentration, K1 is a unitless “ocean uptake constant”, and K2 is a sea surface absorption/temperature constant, with units of PPM per decree C. Delta SST is the year-on-year change in average sea surface temperature. K1 is related to how quickly surface water is replaced by deeper water, and it should be a relatively small number, since ocean circulation and mixing are slow. K2 should be a relatively large number, since surface water temperature changes are relatively fast and we know that there is a strong short-term correlation between the rate of change of CO2 concentration and SST changes.
The model performs an iterative calculation (a step-wise approximation of integration) of the evolution of CO2 in the atmosphere. Each year a change in CO2 is calculated using the above equation, that change is added to the atmospheric CO2 concentration from the previous year, and the process is then repeated. The calculation starts with 1959, using a starting CO2 concentration of 315 (the value from Mauna Loa in 1958).
Measured CO2 values and measured year-on-year changes are from Mauna Loa. Average SST’s are from GISS. CO2 emissions, expressed as PPM potential increase in CO2 in the atmosphere, are based on worldwide carbon emissions (according to CDIAC at Oak Ridge) converted to an equivalent weight of CO2, divided by an assumed atmosphere weight of 5.3 X 10^9 million tons. This result was scaled by a constant factor of 0.7232, which is 28.96/44 = 0.6582 (to convert weight fraction CO2 to volume fraction), multiplied by 1.099 to match up with the range of CO2 emissions that Dr. Spencer used in his May 11 blog post. Note that nobody really knows the total carbon emissions, so different sources offer different estimates of total emissions. The final two years of CO2 emissions I had to estimate beacause the CDIAC data ended in 2006. I assumed an equilibrium ocean CO2 level of 285 PPM. I optimized K1 and K2 by hand so that the model had a reasonable fit with the data; the values were 0.0215 for K1 and 5.0 for K2. So the model equation is:
Annual change = (Annual emissions) – 0.0215 * (CO2 – 285) + 5.0 * (delta SST)
The graph titled “Annual Increase in CO2” compares the measured and calculated year-on-year changes along with the potential increase from fossil fuels.
The graph titled “Correlation: Model Increase vs. Mauna Loa Increase” shows that the model does a decent job of capturing the year-on-year temperature driven change in atmospheric CO2.
I suspect that if the model used monthly data and the 6-month lag between SST changes and CO2 changes that Dr. Spencer used, then the model fit would be better.
The graph titled “Measured CO2 versus Ocean Uptake Model” shows the final result of the calculation.
The evolution of CO2 in the atmosphere calculated by the model between 1958 and 2008 is reasonably close to the Mauna Loa record. The model suggests that about 2.15 PPM equivalent of emitted CO2 is currently being absorbed, or about half the total emissions.
My only objective is to show that the CO2 released by human activities, combined with slow ocean absorption/neutralization and sea surface temperature variation, is broadly consistent with the measured historical trend in atmospheric CO2, including the effect of changing average SST on short term variation in the rate of CO2 increase. Temperature changes in ocean surface waters cause shifts of a few PPM up and down in the rate of increase, but surface temperature changes do not explain 80% to 90% of the increase in atmospheric CO2 since 1958, as suggested in Dr. Spencer’s May 11 post. Because of its relatively high pH, high buffering capacity, enormous mass, and slow circulation, the ocean is, and will be for a very long time, a significant net sink for atmospheric CO2.
With a bit of luck, continuing flat-to-falling average surface temperatures and ocean heat content will discredit the model predictions before too much economic damage is done.
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Steve Fitzpatrick: You wrote, “Average SST’s are from GISS.”
Do you have a link to the GISS SST data?
When you say “The model suggests that about 2.15 PPM equivalent of emitted CO2 is currently being absorbed, or about half the total emissions.” do you mean half of all anthropogenic co2 emission or all co2 emission? Please clarify “total emission”, I assume you mean “total anthropogenic emission”.
Interesting post, thanks
A few weeks ago I posted these plots showing that temperature could be related to CO2. I was hauled over the coals for plotting 2 rising variables against each other. Just as Steve Fitzpatrick does here. My objective was to show that there temperature and CO2 could be linked.
http://img156.imageshack.us/img156/6731/hadcrut3nhvsco2andtsi.jpg
I also derived an expression for temperature rise vs CO2 and plotted hadcrut3-(curve fit temp) vs time showing little erro other than noise:
http://img2.imageshack.us/img2/81/hadcrut3vsco2timeseries.jpg
On a more recent thread there has been discussion about the annual variation in CO2
Firstly NH dominates the world CO2 change (on antarctica has a CO2 level 6 months out of phase with NH. Barrow and resolute have the least filtered changes (sharpest dips) and so the july / august dip must be caused near these latitudes.
Plot of 7 locations fron cdiac data:
http://img190.imageshack.us/img190/1068/co2x7.jpg
Note the sharpness of this summer dip.
My speculation has been to question what can change the CO2 level by this small amplitude about 17ppm in 360ppm.
I have likened it to a NH vacuum cleaner sucking CO2 and then suddenly being switched to blow. Vegetation would be a slow progressive change as spring moves northward. CO2 in the ocean would again be a slow progression. Is perhaps the sudden change in ocean ice the cause of the increase. This could cause the sucking from April to August but this should not get switched off until ice minimum in september. So what starts suddenly blowing CO2 in august?
The slopes into and out of this dip are very similar: into the dip is -3.6ppm/month and out of the dip is 3.1ppm/month.
Another interesting point is that it is generally agreed that SST have increased from 1975 to 2008 but looking at “hourly” plots of CO2 for 3 years (randomly chosen to be near start in middle and at end of records, but I have not checked the rest!) this turnover from -ve slope to +ve slope occurs within about +-1 week of the same day (assuming 365.25 days per year). Wouldn’t one expect a progressive +ve / -ve change?
The hourly data plot:
http://img132.imageshack.us/img132/7442/barrowhourlyco2.jpg
Do you have an opinion about cause of the fine structure within-year wriggles that are on graphs commonly seen from Barrow, Mauna Loa and the South Pole? They are often atributed to vegetation growth in the Northern Hemisphere, but I have trouble seeing this effect translated to the South Pole.
PS.
The point of my post is:
– what causes this dip?
– The dip exceeds the annual change in CO2 by almost an order of magnitude so a small change in the suck blow machine could have a significant effect on averaged co2 level
– Can oceans really cause the dip?
– the propagation of the blip is fast – it appears on christmas island and mauna loa (sh) data with a delay of 1 month from barrow (nh).
So much for tipping points and runaway warming.
The Earth is just as capable of sequestering the C02 that it did over billions of years.
From the looks of the model, it’s more than up to the task.
Hopefully, the flat to lowering surface temps will act like ice water in the faces of a prominent few…before they commit us to Economic HariKari.
I can hear the snickers and guffaws as the rest of the world watches the West knife itself over Polly want a C02 cracker models.
The Earth has evolved over geologic times to become a carbon-eating/energy-storing mechanism, having stored far more than is expelled/released in a cyclic manner. Life has something to do with it.
Some lifeforms get thier thrills yelling Fire on a crowded planet.
“With a bit of luck, continuing flat-to-falling average surface temperatures and ocean heat content will discredit the model predictions before too much economic damage is done.”
Nice to see a bit of optimism here.
And that’s surely the nub of the whole situation, isn’t it? Tackle what Robert D. Brinsmead calls “carbophobia” (http://www.bobbrinsmead.com/E_Vindication_of_Carbon.html) and the rest must follow i.e. the general public starting coming to its senses.
I have long been convinced that carbophobia will bring down Obama. I know many people on this blog will be delighted with such an eventuality – I won’t.
A potentially important difference betwen terrestrial an aquatic (dominated by marine-) systems should be noted. If my memory serves me, the photosynthesis on land (at least the large scale with implications for the carbon-cycle) is strongly attenuated when day-temperature is below 6 deg C. Marine photosynthesis is much less temperature dependent.
Cassanders
In Cod we trust
John Wright (02:56:40) :
“US Energy Secretary Steven Chu says the US will not be able to cut greenhouse emissions as much as it should due to domestic political opposition.”
“Environmentalists said Prof Chu, a Nobel physicist, should be guided by science not politics.”
And yet “Prof Chu told BBC News he feared the world might be heading towards a tipping point on climate change.”
http://news.bbc.co.uk/1/hi/sci/tech/8061929.stm
I regret that the BBC report is written by that biased twit Roger Harrabin, described as Environment analyst, BBC News. Read more about the man at http://bishophill.squarespace.com/display/Search?searchQuery=roger+harrabin&moduleId=1282578&moduleFilter=&categoryFilter=&startAt=0
The BBS report is only worth reading for confirmation that “one compromise would be approving new coal-fired power plants without obliging them to capture and store their carbon. The UK government has made this a stipulation for new coal plants but Prof Chu declined to explain why the US government would not follow suit.”
It’s a start.
bill (02:18:26) :
I would have thought the dip is well aligned with phytoplankton blooms in the higher latitudes in cold, nutrient rich, water during the NH summer.
Perhaps the real question is why there isn’t an even bigger dip during the southern summer, given the size of the Pacific.
OT:
When cam we expect the release of David Archibald’s “Solar Cycle 24” ?
And are we officially into the 24 SN cycle as of now ?
Perry Debell (03:50:14) :
John Wright (02:56:40) :
“US Energy Secretary Steven Chu says the US will not be able to cut greenhouse emissions as much as it should due to domestic political opposition.”
“Environmentalists said Prof Chu, a Nobel physicist, should be guided by science not politics.”
I never wrote that,
John Wright
HappyDayz (04:07:10) :
I would have thought the dip is well aligned with phytoplankton blooms in the higher latitudes in cold, nutrient rich, water during the NH summer.
Perhaps the real question is why there isn’t an even bigger dip during the southern summer, given the size of the Pacific.
Peak melt occurs in september. Does the pytoplankton bloom occur before this?
“Arrigo found that the Cape Bathurst polynya contained considerable variability, in terms of initial polynya formation and in the extent and persistence of open water, over a five year period (1998-2002). Phytoplankton blooms also varied considerably in intensity and timing. Phytoplankton are plantlike organisms that contain green chlorophyll and are a primary food source for many marine mammals and birds, are tiny organisms that are responsible for most of the photosynthetic activity in the oceans.”
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/11/20/MNV1147VJE.DTL
http://www.nasa.gov/centers/goddard/earthandsun/arctic_changes.html
This graphic ( 1998 phytoplankton bloom in the Cape Bathurst polynya region)seems to show that the bloom is centred between 21st may and 23rd june which is not when the dip occurs
http://www.nasa.gov/centers/goddard/images/content/106331main1_chlorophyll_seawifs_t.jpg
These refs say that the bloom is affecterd by temperatures. The timing of the minima is not.
No me parece correcto considerar solamente el fenómeno físico-químico de solubilidad. La absorción de CO2 en realidad la realiza el fitoplancton. Si disminuye la temperatura el CO2 disuelto (alimento) es mayor, la actividad de fotosíntesis es mayor y la absorción de CO2 aumenta. A pesar de que al aumentar la temperatura hay un menor consumo del fitoplancton (absorción) y que los océanos siempre desprenden CO2 por la actividad bacteriana, nunca hay una emisión neta a la atmósfera como saldo de estos procesos.
I think is not correct to consider only the physical phenomenon of solubility. The absorption of CO2 actually makes phytoplankton. If the temperature decreases dissolved CO2 (food) is higher, then the activity of photosynthesis is higher and the absorption of CO2 increases. Despite the fact that with increasing temperature there is a lower consumption of phytoplankton (absorption) and that the oceans give off CO2 provided by bacterial activity, there is never a net emission to the atmosphere as the balance of these processes.
This post typifies much of what passes for scientific analysis. First make unjustified assumptions, next ignore the massive errors in your estimates , ignore that the amount of human emission is a mere 3% of the total flux exchange which pretty much invalidates the whole numerical exercise, then produce a few graphs which surround your guesswork with a pseudo-scientific veneer.
The initial assumptions that stand out for me are:
1. Assume a net ocean sink without giving any mechanism for it whatsoever. As temperatures have been rising since the little ice age and it’s accepted even here that rising temps should cause the waters to disgorge CO2 rather than uptake it, so this starting assumption is just unphysical. To get around problem we always get some handwaving with references to deep water, circulations, or in this case “old water” and this post is no exception. Never mind that what oceanographers actually know about ocean movements is continually confounded and wrong. Witness the number of oceanographers who still say that the gulf stream warms Europe and it could be interrupted by the warming while Wunsch and Seager state show that this is a ridiculous myth among oceanographers which would require the planet to stop spinning to become true. There may actually be a mechanism for ocean uptake but I’ve yet to see anyone properly describe it.
2. Land uptake is so small it can be dispensed with altogether. This oddity seems to arrive from these other IPCC assumptions:
a) assumption A: the planet manmade deforestation gives a net increase of 20% of emissions. However the planet is greening (link given in Spencer post) and deserts are shrinking so this assumption is nonsensical.
b) assumption B, which actually contradicts assumption A: Counting the green bits on the planet shows 6% increase in NPP in 30 years (and lets just ignore that it is 25% increase in vegetation) but in fact the CO2 storage is not in the leaves. When you measure the increase in the brownery it turns out that you find an extra 5 Gigatonnes with little effort (Link given in the Spencer post). How many extra carbon sinks could we find just by assuming the most logical explanation and going out to look for them?
c) assumption C (not important for the numbers but worthy of mention as the most ridiculously speculative): While it’s certainly greening now it surely won’t be if the temperature gets much higher.
d) Lastly, that the CO2 is actually increasing unnaturally in the first place. This of course seems utterly logical given that the planet is warming, we are emitting more and that we have several locations apparently showing this monotonic increase. But I linked already (on the Spencer thread) to a monitored desert location that should have shown an increase in line with Mauna Loa. It however showed no trend at all. Honestly, the fact that the land flux is 450 Gt, the ocean flux is 250 Gt and our contribution is between 7 and 27 Gt (depending on who’s official guesswork is used) should really give a few more people pause for reflection. We should also be wary of any data that isn’t available in raw, unadjusted form.
Here’s an alternative hypothesis. All that we emit (between 7 and 27 Gt), being emitted pretty close to ground level is mainly soaked up quickly by plant life. Sea emissions are increasing naturally in response to temperature. Now for this hypothesis to be correct then desert locations should not see any increase in CO2 but all seaboard locations would. Easy to test: I see your Mauna Loa and I raise you one Nevada FACE experiment.
I do not think anyone knows much about the physics and chemistry of gas emission and absorption in the open ocean.
On point is the following:
The Acquittal of Carbon Dioxide, by Jeffrey A. Glassman, PhD.
http://www.rocketscientistsjournal.com/2006/10/co2_acquittal.html#more
ABSTRACT
Carbon dioxide in the atmosphere is the product of oceanic respiration due to the well‑known but under‑appreciated solubility pump. Carbon dioxide rises out of warm ocean waters where it is added to the atmosphere. There it is mixed with residual and accidental CO2, and circulated, to be absorbed into the sink of the cold ocean waters. Next the thermohaline circulation carries the CO2‑rich sea water deep into the ocean. A millennium later it appears at the surface in warm waters, saturated by lower pressure and higher temperature, to be exhausted back into the atmosphere.
Throughout the past 420 millennia, comprising four interglacial periods, the Vostok record of atmospheric carbon dioxide concentration is imprinted with, and fully characterized by, the physics of the solubility of CO2 in water, along with the lag in the deep ocean circulation. Notwithstanding that carbon dioxide is a greenhouse gas, atmospheric carbon dioxide has neither caused nor amplified global temperature increases. Increased carbon dioxide has been an effect of global warming, not a cause. Technically, carbon dioxide is a lagging proxy for ocean temperatures. When global temperature, and along with it, ocean temperature rises, the physics of solubility causes atmospheric CO2 to increase. If increases in carbon dioxide, or any other greenhouse gas, could have in turn raised global temperatures, the positive feedback would have been catastrophic. While the conditions for such a catastrophe were present in the Vostok record from natural causes, the runaway event did not occur. Carbon dioxide does not accumulate in the atmosphere.
I wonder what deep ocean current model was used?
“Uh, oh. 50 year old ocean thermohaline model sinking fast, climate models may be disrupted”
http://wattsupwiththat.com/2009/05/15/uh-oh-50-year-old-ocean-thermohaline-model-sinking-fast-climate-models-may-be-disrupted/#more-7875
It’s probably staring me in the face but where is the link to the Dr Roy paper from May 11?
Steve,
Some things about this model seem counter intuitive to me. If I understand you correctly, (emissions) are anthropogenic emissions only? If yes,
1. Why would annual emissions be limited to anthropogenic emissions?
Then,
2. How could K1 not vary by temperature?
3. What data supports the assumption of 285 ppm as a point of equilibrium in this absorption?
4. If no one really knows the actual total emissions (and here I mean anthropogenic as well as natural), how can we determine anything?
OT, but worth noting given the green hype/carbon tax bunk as of late….
Sanyo hits world record for solar cell efficiency
http://www.tgdaily.com/content/view/42559/135/
Unfortunately, a whopping 23% does very little to replace current electricity generation, especially given battery limitations. It would be nice if the efficiency was greater than 50%….one can always hope, I guess!
Bob Tisdale (01:30:26) :
This link: http://data.giss.nasa.gov/gistemp/graphs/ allows you to download text data as well.
stumpy (01:48:42) :
‘do you mean half of all anthropogenic co2 emission or all co2 emission? Please clarify “total emission”, I assume you mean “total anthropogenic emission”’
Yes, that is what I mean. The overall annual exchange rate between the atmosphere carbon sinks (mainly land plants, top soil carbon, and ocean absorption) is much greater; on the order of 20% of the total atmospheric CO2 (~75 PPM equivalent), and presumably this process would be close to “in balance” without any increase in atmospheric CO2. Adding CO2 to the atmosphere increases plant uptake and ocean absorption and leads to a net flux from the atmosphere to these carbon sinks.
bill (02:05:30) :
I do not know why you would be dragged over the coals for plotting CO2 versus temperature; seems a reasonable thing to do. However, perhaps a better plot would be Ln(CO2) versus temperature, since the radiative effect of CO2 should be a log function of concentration, not linear. However, CO2 represents only ~55-60% of the total increase in infrared absorbing trace gases (methane, fluorocarbons, ozone, etc. cause the rest). Methane concentration is currently falling slightly, after increasing from the 1800’s through the 1990’s, while fluorocarbons have been falling since the early 1990’s. Perhaps a more robust plot would be increase in temperature versus the log trends in all these trace gases. From the 1950’s to the mid-1990’s, CO2 concentration may have been a fair stand-in for all the trace gases, but since then CO2 and the others are going their separate ways.
Don’t forget Dr. Spencers purpose was to show that a simpler model fit the data as well or better than the popular one. He did just that, I didn’t see him claiming that this was all there was to it. His model does fit the paleo record and fits the current data as well or better than any of the popular AGW models.