Category: acidification


A part of my John Everett series – read more: 0/I – II.0 – II.5 – II.75 –  III.0 – III.3 – IV.0 – IV.4 – IV.8 – V – VII – VIII – Full Report 

Often, in order to explain why a particular Weird Belief is correct despite being at odds with available evidence, the belief holder will invoke conspiracy theories. Young Earth Creationists often invoke a conspiracy by god and/or satan to make the earth look much older than it actually is. Intelligent Design Creationists allege an academic conspiracy to suppress ID research. Climate change skuptiks see conspiracies to falsify data the way I see faces in clouds. It’s not necessarily that conspiracies don’t exist- but because the point of a conspiracy is to mask its own existence, we have to be very careful in deciding which conspiracy theories are justified and which aren’t.

Dr. Everett doesn’t invoke a conspiracy in the classical sense of a bunch of men in suits, smoking cigars in a dimly lit room. But he does seem to invoke a distributed, systemic conspiracy, in which science as a system has been corrupted, and its results can not be trusted. He does this in order to cast doubt on studies of the effects of acidification on calcifiers:

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A part of my John Everett series – read more: 0/I – II.0 – II.5 – II.75 –  III.0 – III.3 – IV.0 – IV.4 – IV.8 – V – VII – VIII – Full Report 

Coccoliths: microscopic death stars of the ocean. Via Wikimedia Commons

Have you ever gone camping with someone who doesn’t know how to build a fire? It might go something like this: you get a pile of twigs burning, and immediately your friend starts piling on huge logs. The fire dwindles. “Hey,” your friend says, “This fire sucks. It must need more logs.” If some fuel is good, then more must be better. It’s a terrible way to roast marshmallows. And yet it’s the philosophy that Dr. Everett applies to the effects of increased carbon dioxide on life.

Here’s an example from part I of his testimony:

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A part of my John Everett series – read more: 0/I – II.0 – II.5 – II.75 –  III.0 – III.3 – IV.0 – IV.4 – IV.8 – V – VII – VIII – Full Report 

The last couple posts looked at Dr. Everett’s discussion of the growth rate of carbon dioxide. There’s one other claim in this section which warrants inspection: that a constant airborne fraction is a challenge to projected acidification.

I got the bright idea to sudo rm -rf in my /etc/ and now GIMP is broken. So none of my sweet graphics this episode. Instead here's a diagram of the carbon cycle, courtesy of NASA (click for sauce.) It's just as well. The coolest thing I could think to draw was some pictures of pie. Mmmm pie.

Here’s what he has to say:

The meaning of this information [the supposed leveling off of CO2 growth rate] (and the future of all climate models[)] became VERY cloudy on 31 December 2009 with the ScienceDaily acknowledgment of a paper published by American Geophysical Union and authored by Wolfgang Knorr that shows “No Rise of Atmospheric Carbon Dioxide Fraction in Past 160 Years”, despite the predictions of carbon cycle/climate models3. The implications of this have yet to be assimilated by the modeling community. This does not mean that CO2 proportion is not rising but rather that the proportion not being assimilated has not changed since 1850. Importantly, it means that the rate of CO2 cycling increases as it becomes more concentrated, and does not decrease as assumed in climate models. The rate of projected growth in CO2 appears to be greatly exaggerated.

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A part of my John Everett series – read more: 0/I – II.0 – II.5 – II.75 –  III.0 – III.3 – IV.0 – IV.4 – IV.8 – V – VII – VIII – Full Report 

The CO2 scenarios are literally falling flat and need revision. The observational trend line shows monotonic growth – pretty much a straight line as in the chart below of global marine CO2 measurements (NOAA data)4, while the IPCC scenarios used in most research rely on an accelerating growth. Certainly the predicted rapid acceleration of the IS92a model (see solid black line in middle of the figure on the right) is missing from the NOAA data plotted below. In fact, if the last 8 or 12 years are representative of the future, we might imagine a downward slope in the growth rate.

Last time, we looked at one claim Dr. Everett makes in this paragraph: that the measured rate of change in atmospheric carbon dioxide is inconsistent with the emissions scenarios used to predict future ocean acidification. To do this, he plays fast and loose with quantities and their derivatives (the rates at which they change.) The imprecision extends even to his quoted numbers: in pidginthe previous paragraph, he gives a growth rate as “3.05 ppm”. That’s a not a growth rate; it’s a concentration. He means 3.05 ppm per year. His projection is an extrapolation of “the average rate of increase for the past 10 years (1.87/year)…” 1.87 WHAT per year? I know that he means 1.87 ppm/year, but a lot of people wouldn’t, and I shouldn’t have to make assumptions. If Everett is being sloppy with his units, he’s being sloppy with his science.

The other claim that Dr. Everett draws from the rate of change in CO2 is that “the growth rate seems to be leveling off, if not declining […] In fact, if the last 8 or 12 years are representative of the future, we might imagine a downward slope in the growth rate. ” Look at the graph of the growth rate again. It goes up and down- a lot.

The record of changes in atmospheric carbon dioxide since 1980. It's got it's ups and downs. Click to see the full record back to 1959.

A part of my John Everett series – read more: 0/I – II.0 – II.5 – II.75 –  III.0 – III.3 – IV.0 – IV.4 – IV.8 – V – VII – VIII – Full Report 

The last post covered Dr. Everett’s introductions; now we’re going to move on to part II of his testimony, titled “The Physics”. In this section he questions estimates of future acidification.

Dr. Everett never seriously challenges the 0.1 pH of acidification which has already occurred, or that human CO2 emissions are the cause (though he will in later sections challenge its impact). His purpose in this section is to challenge projections for future acidification, on the basis that less carbon dioxide will be emitted than is projected in the models used:

…if the projections we are concerned with today are based on the IPCC IS92a model, […] we should give the information on its impacts a second look.

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We’ve all at least heard of the greenhouse effect and global warming: trace gasses (primarily carbon dioxide) in the earth’s atmosphere alter its thermal properties, causing it to retain heat. Human activity, primarily the burning of fossil fuels, is increasing the carbon dioxide content of the atmosphere and as a result heating up the earth. However, a less appreciated fact is that in addition to changing the atmosphere’s thermal properties, carbon dioxide can also be a chemical pollutant.

Many people will likely startle at that last line- after all, we all exhale carbon dioxide; plants use it for food; I’m sitting breathing it right now with no ill effects (the oxygen I’m also breathing is arguably a more pressing chemical threat). CO2 certainly doesn’t have the toxic appeal of PCBs or dioxin.

But a pollutants aren’t just nasty oil slicks. A pollutant is a substance which, by virtue of its chemical activity, interferes with the functioning of an ecosystem. A pollutant is an ecophysiological poison. And poisons are situational: whether or not a substance is poisonous depends upon its amount, the rate it’s encountered, and other factors. To draw an analogy with the human body, there are plenty of chemicals which in some situations are essential, but poisonous in others. Nitric oxide, carbon monoxide, and hydrogen sulfide are all essential signalling molecules in our nervous system- but they’re also all quite poisonous. Hydrochloric acid is important in my stomach, where it helps me digest food- but I don’t want to get it in my eyes.

The other CO2 problem” is ocean acidification. Carbon dioxide, in addition to being a greenhouse gas, is acidic. When carbon dioxide (CO2) dissolves in water (H2O) the carbon atom in CO2 has a slight positive charge, while the oxygen atom in water has a slight negative charge. Just like your hair and a balloon stick to each other after you rub them together, the two molecules stick together. The result is a single molecule called carbonic acid- acid, because the hydrogen atoms are liable to fall off.

Carbon dioxide is acidic: reacting it with water produces carbonic acid.

Reacting carbon dioxide with water produces carbonic acid.

As we pump more carbon dioxide into the air, we are indirectly pumping more carbon dioxide into the ocean and in the process we’re making it more acidic. This can have several ecological effects; the most obvious is on calcifying organisms like corals. When carbonic acid forms and releases hydrogen atoms, some of those hydrogens recombine with carbonate to form bicarbonate. Since corals’ exoskeletons are made of calcium carbonate, acidification poses a threat to them and the ecosystems that they harbor.

The carbonic acid / bicarbonate / carbonate buffer system.

Atmospheric CO2 winds up in the ocean, where it undergoes a series of reactions. As more CO2 is added to the air, more flows into the ocean, where it forms carbonic acid. Some of that carbonic acid in turn loses a hydrogen ion to form bicarbonate. However, as hydrogen ions build up, they react with carbonate to turn it into bicarbonate- which is a problem if you're a sea creature using that carbonate to build shells.

Just as we can already detect changes in the global climate from increased atmospheric carbon dioxide, we are also starting to see changes in ocean chemistry. Below is a graph linking the two – on the top is a graph showing the increase in both atmospheric and oceanic carbon dioxide over time. The other graphs show the associated decrease in pH (pH is a measure of acidity of a solution – the lower the pH, the more acidic. pH is also logarithmic, which means that big changes look smaller than they are: a change of 0.1 pH changes the acidity by a factor of about 125%). The pH graphs, in orange and green, show measurements from successively deeper parts of the ocean, and we can see that the change is greatest closer to the surface, confirming that the change is due to changes in the atmosphere.

click for teh sauce

Measurements of carbon dioxide in the air and oceans (top) and the accompanying drop in pH. pH is a measure of acidity; keep in mind that more acidity means a smaller pH. Taken from Dore et al. 2009; click for the full paper.

The science of anthropogenic climate change has been politically and economically inconvenient for many people, and a cottage industry has popped up in trying to dismiss it. As I will discuss in the next few posts, we are also starting to see the political campaigns devoted to denying climate change turning their attentions to ocean acidification.