The Oceans are Absorbing Large Quantities of Carbon Dioxide

Alan Siddons recently pointed out that NASA’s James Hansen has been complaining that 44% of anthropogenic CO2 goes missing EACH YEAR, but CDIAC’s data clearly show that the situation has become far worse than that from the alarmist viewpoint.  Alan Siddons found when looking at the CDIAC 2016 Global Carbon Project spreadsheet, under the Historical Budget tab, that he could graph both the annual increase in gigatons of carbon for the atmospheric CO2 concentration growth and for the change in carbon in the Ocean. The values to be discussed here do not resolve man's contribution from natures contribution.   They are total changes in carbon dioxide in each case. The resultant profile was not what he expected.  The additional carbon dioxide dissolved in the ocean in red is compared with the additional carbon dioxide in the atmosphere in Alan Siddons plot below.

Since a shallow minimum in about 1840, the amount of the increase in the ocean concentration of CO2 has increased almost every year.  Generally the atmospheric concentration of CO2 has increased except for two brief periods of reductions around 1820 and 1856.  There was a strong decrease in the amount of the increase centered on about 1946.  Because the surface water layer of the oceans is attempting to come into equilibrium in dissolved CO2 content with the atmosphere, but there is substantial exchange between the warm surface layer and the colder ocean depths, the general increase in CO2 in the atmosphere since the end of the Little Ice Age will result in more dissolved CO2 in the ocean for a given surface temperature for a long period of time.

In 2004, the additional CO2 dissolved in the oceans and other waters of the Earth was a bit more than 60% of the additional carbon dioxide in the atmosphere, not the 44% that was already so high in James Hansen's mind as to be a troubling indicator of the disappearance of CO2 that he expected to remain in the atmosphere.   For him, this disappearance was a problem with respect to the catastrophic man-made global warming hypothesis with its claims that man's emissions of CO2 from fossil fuel use and the making of cement would leave that CO2 in the atmosphere for a hundred years or thereabouts.  Basically, these high atmosphere residence times are threatened by the high solubility of CO2 in water and the overturn of the surface layer of water with colder water from below.  At 25°C, CO2 is about 26 times more soluble in water than is molecular oxygen.

We are told by the settled science that increased atmospheric CO2 causes warming.  Yet, everyone knows that a warming ocean should release CO2, thereby adding to the CO2 in the atmosphere.  If that picture is right, do we not expect the ocean to act like a source of further CO2, rather than a sink, because CO2 in the atmosphere is supposed to warm the oceans?

Perhaps not.  Let us examine this exchange or equilibrium condition for CO2 between the ocean and the atmosphere. The mole fraction of a gas, X, dissolved in water is given by 

X = (v/RT) e^H/RT P,

where v is the free volume occupied by a mole of water, T is the temperature in Kelvin, H is the heat of vaporization of the gas from water, P is the partial pressure of the gas over the water surface or in the atmosphere, and R is the gas constant, as in the Ideal Gas Law equation PV = nRT, where n is the number of moles of the gas and V is the volume of the gas.  The mole fraction is the number of dissolved gas moles in the water divided by the sum of the number of water moles and the number of gas moles.  For the low pressure cases we will be examining, the denominator is essentially the number of water moles since the number of gas moles will be much, much smaller.

Because the mole fraction of the dissolved gas decreases as the temperature increases in this formula at constant P proportional to (P/T) e^H/RT , it is commonly assumed that changes in the temperature are the dominant control knob with respect to the solubility of CO2 in the oceans.  But, note that a change of the surface temperature of 0.7°C from 14.65°C to 15.35°C 

means that the ratio of the temperatures on the Kelvin scale is only 288.50K/287.80K = 1.00243.

For the sake of this thought experiment, let us assume, albeit wrongly, that the increase in atmospheric CO2 since 1850 has caused a 0.7°C or 0.7 K temperature increase as the atmospheric concentration of CO2 went from 280 ppm to 400 ppm. Then a 0.7 K temperature increase to present temperatures would be due to about a 120 ppm increase in CO2 concentration using a linear relationship as the alarmists are wont to do.  It would actually take more of a CO2 increase than that due to the logarithmic saturation of the CO2 absorption of surface thermal radiation  with concentration, but let us use their numbers anyway. The present to 1850 ratio of CO2 atmospheric concentrations is 400 ppm /280 ppm =1.43 or a 43% increase in the partial pressure of CO2 in the atmosphere.

The Handbook of Chemistry and Physics, 96th Edition, has a table for the solubility of carbon dioxide in water.  With a 5 kPa partial pressure of CO2 it says the mole fraction of CO2 is

10°C, X = 0.000048 = 48 x 10^-6

15°C, X = 0.000041 = 41 x 10^-6

20°C, X = 0.000035 = 35 x 10^-6

Let us examine the rate of change of the mole fraction with temperature, while holding the pressure constant.  From 10 to 15°C, the rate of change is a decrease of 7 x 10^-6 / 5 K and from 15 to 20°C, the rate of change is - 6 x 10^-6 / 5 K.  Thus at about 15 C, the rate of change is about - 6.5 x 10^-6/ 5 K = - 1.3 x 10^-6 / K.  All of this is for the partial pressure of 5 kPa.

There are 101.325 kPa in one standard atmosphere.  A partial pressure of CO2 of 400 ppm is then (0.000400 atm.) (101.325 kPa/atm.) = 0.0405 kPa. Since the mole fraction X is proportional to the partial pressure of CO2 in the atmosphere, the mole fraction X at 0.0405 kPa is much lower than this lowest partial pressure in the Handbook of Chemistry and Physics table of solubility.  We have

X = [0.0405 kPa)/ (5 kPa) ](0.000041) = 0.332 x 10^-6 

at 15°C.  The rate of decrease of X near 15°C with a temperature increase at the partial pressure of 400 ppm at a temperature of 15°C is then  

dX /dT = [0.0405 kPa)/ (5 kPa) ] ( - 1.3 x 10^-6 / K) = - 0.0105 x 10^-6 / K.

If we increase the temperature by 0.7°C as it has been claimed is the case since 1850 for the Earth's surface temperature, then near 15°C the decrease in X due to the temperature increase is about ( 0.7 K ) ( - 0.0105 x 10^-6 / K) = - 0.0074 x 10^-6.  Consequently, the mole fraction X after the temperature increase is about 

X = 0.332 x 10^-6  - 0.007 x 10^-6  = 0.325 x 10^-6 

due to the temperature increase of 0.7 K.  The mole fraction was therefore reduced to 97.9% of its prior value by the 0.7 K temperature increase.

But, when increasing the temperature, the partial pressure of CO2 was increased from 280 ppm to 400 ppm, an increase in the partial pressure by a factor of 1.43.  Since the mole fraction is proportional to the partial pressure of CO2, this means the mole fraction was increased by 43%, which is vastly larger than the 2% decrease due to a 0.7 C temperature increase.

Consequently, for the conditions on Earth, the oceans are a strong sink for CO2 as the CO2 concentration in the atmosphere increases.  What is more, increases in the concentration of CO2 in the atmosphere lead to smaller and smaller increases of the absorption of the Earth's surface thermal radiation, but the solubility of CO2 in the oceans and other waters of the Earth's surface remains proportional to the partial pressure of CO2 in the atmosphere. Thus, for a given increase in the absorption of the Earth's surface radiation or contribution to a temperature increase by that saturating mechanism, more and more CO2 will be absorbed by the oceans for any increase the absorption of surface thermal radiation.

The data that Alan Siddons plotted above shows this effect, much to the consternation of James Hansen.  The more CO2 you put in the atmosphere, the more gets sucked out of the atmosphere by the oceans and water generally, including even water bound up in minerals or soil.  The solubility of CO2 is proportional to its partial pressure, which has increased greatly, while temperature changes measured against the absolute Kelvin temperature scale are very small.  The more CO2 you put in the atmosphere, the less effect it has in absorbing further thermal radiation from the Earth's surface.  The atmospheric CO2 concentration changes are dominant compared to the temperature changes in solubility, which helps to stabilize the atmospheric CO2 concentrations and the resulting temperature.

But it is even worse than this for the alarmist cause, because Alan Siddons made another extremely critical discovery when examining the government's data on CO2 emission increases by man and comparing those annual increases with the government data on the annual increases in the atmospheric concentration of carbon dioxide.  He discovered that man's carbon dioxide emission increases each year were a small fraction of those due to natural causes.  Man's emissions are only 4 to 5% of the total annual additions of CO2 to the atmosphere averaged over the period back to 1960.

Now, one's first thought about where the huge natural CO2 emissions are coming from would be that it might be the oceans, but as we saw above, the oceans are a large sink for added CO2.  They are not the source. Things are getting mighty interesting!  Scientists clearly need to spend more time learning about nature and a little less trying to damn mankind.  Unfortunately, they are clearly being paid by most governments and the UN to make a case, no matter how, that mankind is evil and determined to destroy the planet.

Of course, some of the alarmists will say, see the oceans are acidifying and isn't that just awful.  But, ocean plant life, mollusks, and coral reefs consider CO2 as much food and construction material as do land plants. They actually thrive on what is still an alkaline ocean with plenty more CO2 for shell building, reef building, and plant food.  On this subject, see: 

Washington Post and Published Research Falsely Report Largest U.S. Reef Dissolving Due to Increased CO2

Washington Post and Published Research Falsely Report Largest U.S. Reef Dissolving Due to Increased CO2

Chelsea Harvey reports in the Washington Post that the work of University of Miami and Florida International University researchers concludes that the Florida Keys Reef is dissolving and it is because of man's use of fossil fuels.  The research was published in the journal Global Biogeochemical Cycles and is based on surveys of the reef throughout the Florida Keys from 2009 to 2010.  The researchers analyzed the water from near the reef to determine whether the reef was dissolving or calcifying according to the Washington Post article.

The period of time in this study is short and its main conclusions were related to seasonal changes in the growth or loss of reef.  It is from these seasonal changes and their differences between the northern and the southern parts of the reef that the authors made conclusions about the long term health of the reef under assumed increasing atmospheric carbon dioxide concentrations.

The abstract for the paper says that the northern portions of the reef had a net annual loss with the fall and winter being the seasons with losses.  The mid-reef section had losses in the fall and winter, but had a net annual gain.  The southern reefs gained in all seasons.

I have extracted key points in the argument presented in the Washington Post article for evaluation below:

The culprit appears to be ocean acidification, a chemical process that happens when carbon dioxide dissolves in the water and undergoes a reaction that lowers the ocean’s pH. When this happens, several consequences can occur, according to the new study’s lead author, Chris Langdon, chair of the University of Miami’s department of marine biology and ecology.

First, when water becomes more acidic, limestone — which is what makes up the hard, rocky skeletons secreted by corals — can start to dissolve, “just like you dropped a sugar cube in water,” Langdon said.

It’s still unclear why the scientists observed such a gradient in the Keys from north to south, with the northernmost corals getting the worst of the deal. According to Langdon, acidity is known to vary from north to south, since colder water is able to hold more dissolved carbon dioxide.

In 2014 and 2015, the reef experienced an unprecedented bleaching event and widespread disease outbreak, likely brought on by both the effects of climate change and 2015’s unusually severe El Nino event. 

“This is concerning because the 2016 summer is predicted to be as hot if not hotter on the reefs,” Walker said in an email to The Washington Post.

Now it is true that if the ocean were acidified by sulfuric acid, the acidity would increase the rate of dissolution of the limestone in the coral reefs.  But if the acid component in the alkaline water is carbonic acid, the weak acid that dissolved CO2 forms, one has actually decreased the chemical concentration gradient of CO2 between the water and the reef limestone materials.  This would have the effect of slowing the dissolution rate.  What is more, one has increased the supply of dissolved CO2 which is the source from which the reef coral organisms get the CO2 they need to produce CaCO3, which is calcium carbonate or limestone.  There may be more to think about here than that simple narrative that a less alkaline or basic ocean means there are smaller and fewer reefs.  Less alkaline is what they call "acidification."  In fact, in the geological record, there have been times warmer than the present and with higher atmospheric carbon dioxide concentrations when reefs did very well.

It is interesting that when the reef organisms are most readily able to build the Florida Key reefs includes the spring and the summer, while dissolution or lower rates of growth occur in the fall and winter.  In fact, the average relative growth rates the study found for the entire Florida Keys by season were (measured in mmols/(sq. m)(day):

Spring, +62
Summer, +17
Fall, -33
Winter, -7

Consequently, if the acidification hypothesis were right, we would expect that the atmospheric CO2 concentration is the highest in the Fall and lowest in the Spring.  Yes, it is actually the CO2 concentration in the water that matters, but reefs are in shallow water that should come into equilibrium with the atmospheric CO2 concentrations quite quickly, especially in the Florida Keys. Let us look at the seasonal variation of atmospheric CO2:

The CO2 concentration is highest in May or the Spring and lowest in September and October, which puts the low value at the border between Summer and Fall, though edging more into Fall.  So the ocean should be less alkaline in the Spring when the atmospheric CO2 concentration is higher and most alkaline in early Fall when the CO2 concentration is low. There is actually a need to also make an adjustment for the seasonal changes in water temperature also.  Because the spring water is still cool after winter and the fall water, especially in early fall, is still warmer on the heels of summer, the spring water concentration of CO2 will be even greater compared to the fall CO2 concentration as shown in the atmospheric carbon dioxide concentration cycle above.  The cooler Spring water will have a higher concentration of CO2 for a given atmospheric concentration than will the cooler Fall water at the same atmospheric concentration.

The Florida Key reefs actually grew much the most in the Spring when the CO2 was at its highest concentration and lost much the most mass in the Fall.  This does not correlate well with the "acidification" model.  Indeed, this is the exact opposite of the seasonal variation demanded by the "acidification" hypothesis.  The clear implication is that when the reef organisms have the maximal supply of dissolved CO2 in the ocean water, they can best produce the calcium carbonate they need for their reef-building activities.  This result should not come as a surprise.

It is also strange to explain the net loss of reef mass in the northern reefs as the result of global warming, aggravated by a warming due to an El Nino which does not require added CO2, when the warmer weather of the summer is a time of reef growth all along the north to south length of the reef.  Yes, they say the additions of atmospheric CO2 due to global warming allows more CO2 to be dissolved in the ocean in the cooler waters of the northern Florida Key water, so they claim there is more acidification there compared to the southern part of the reef.  The north-south change in temperature is much smaller than the seasonal change of temperature, so the temperature change is a secondary effect compared to the CO2 concentration in water effect.  Reef building is helped when the supply of CO2 is greater.

Such warming as is due to the El Nino actually decreases CO2 in the ocean because less will dissolve in water that is warmer.  El Nino makes the water more alkaline, not more acidic.  Consequently, they are not even consistent in combining these two warming causes for a common affect on the reefs. The warming due to an El Nino decreases the supply of CO2 in the water slightly, so it may be somewhat harmful to reef growth from that standpoint, but not due to acidification.

Still another problem with this argument is that the temperature difference between the northern and southern Florida Key reefs is not nearly as great as that between the Summer and Winter seasons for any stretch of the reef.  Yet in the warm summer, reef growth occurs everywhere and it occurs best in the southern reefs.  Warmer water appears to be good for the growth of the reefs, though not as good as is having a maximal supply of CO2.  So the argument that a warming of the ocean is a problem in itself for the reef is clearly unsupported by the evidence.  There are also reefs in more equatorial areas than the Florida Keys that are doing well.

In conclusion, while the study of the seasonal variations in the growth of the Florida Keys Reefs provides valuable information on those seasonal differences, all the wrong conclusions were drawn from those results in the peer-reviewed and published scientific paper and in the Washington Post article as well.  The researchers and the reviewers did a very poor job on this paper.  It should never have been published in the form it was published in.

The real conclusion of this paper should have been that the biggest factor affecting reef growth appears to be the amount of CO2 available to the coral organisms and more CO2 is much better than less CO2.

The Ocean Acidification Myth

Professor Cliff Ollier of the School of Earth and Environment at the University of Western Australia has written an interesting and entertaining article on the myth of ocean acidification.  The oceans are always alkaline or basic, not acidic.  The acidity or alkalinity of water is measured on a logarithmic scale from 0 to 14, with 7 being neutral.  This is the pH scale and basic pH is greater than 7, while acidic pH is less than 7.  The oceans are commonly about pH 8.2 and it is very difficult to reduce the basic water even to neutral water because this is a logarithmic measurement.  Through at least the last 600 million years the oceans have not been acidic.  The most added dissolved CO2 does to the oceans is make them less basic or alkaline.

Among Professor Ollier's interesting comments:

• CO2 is critically needed by coral, shellfish, and marine plants.
• A volcanic vent bubbling huge amounts of CO2 to the surface is a favorite of divers because of the thriving life there, including corals.  The water there is fully saturated with CO2.
• Ocean pH varies by 0.3 by region and seasonally by 0.3 in a given area.
• The day to night variation in a coral pool was found to be 9.4 to 7.5, making claimed variations due to atmospheric CO2 look very inconsequential.
• Marine life evolved at much higher atmospheric concentrations of CO2 than we have now or would have if CO2 atmospheric concentrations doubled.  As is the case with land plants, it appears that marine life is better served by higher CO2 concentrations.
• Under good conditions, a coral reef can grow by 2 cm a year and added CO2 helps.  [From 1870 to 200, the average rate of sea level rise is claimed to be 1.5 mm a year.  Faster rates of as high as 3.3 mm a year have been claimed for 1993 to 2009, but coral reef islands can keep up.  Indeed, they have to have had this capability to deal with past climate changes over the last few hundred million years.]  Most atoll islands are doing well in keeping up.
• Human additions of CO2 to the atmosphere compared to what some plants and animals have removed in making limestone are trivial.  There is far more CO2 in limestone than there is in the oceans and the atmosphere combined.  Because the oceans remain alkaline, this stored CO2 in the form of limestone is not released and the result is a CO2 deprived planet.