The Story So Far
In a previous post I was talking about Piers Corbyn and his strange obsession with termites. The claim was that termites emit ten times the CO2 as humans, and I pointed out that the only source he quoted for that extraordinary claim was a list of fun facts on a website for a termite detector company, and he ignored contradictory facts from that very source.
But that left the question as to whether there was any truth in the claim, and if there isn't where did the claim originate.
Zombie Termites
Piers is not the first to have made the claim.
In fact the claim has been around for at least 25 years,
and has all the hallmarks of a zombie statistic - one that is repeated so often it can never be killed.
It's a suspiciously round number - ten times anything has a certain shock value that 9 times or 11 times doesn't.
Then there's the lack of clarity, ten times human output from what year, and do we mean all human activity, or just from fossil fuels.
And I can find no instance of someone given precise figures and sources both for termite and human emissions -
nobody says According to this research termites emit X amount of CO2. According to this research humans emit Y amount of CO2. Note that X is 10 times Y.
.
The question of the time frame for the claim is important as human emissions have increased over the last few decades, as this graph demonstrates.
Emissions have doubled since , so if termites had been emitting 10 times as much back then, they'd only be emitting 5 times as much now.
Looking for a Source
Alan Caruba
The earliest online example of the claim I could find was from , in an article by Alan Caruba, with the equivocal title Global warming: Lies, lies, damnable lies!.
Carbon Dioxide is a natural, abundant chemical that is essential to the growth of all plants and trees. You and every other member of the planet's six billion human population emits CO2 every time they exhale. Termites produce ten times the amount of CO2 than all the fossil fuels burned in a year worldwide. The technology of energy production, transportation, etc., has been calculated to be only 0.04 per cent. The UN Kyoto Climate Control Treaty is intended to control that! Do you think 0.04 per cent has any effect? The notion of calling CO2 a "pollutant" is ludicrous. Worse, it is a criminal fraud.
As is often the case it's thrown in amidst a number of irrelevant claims, and provides no source. He makes an even odder claim that energy production and transportation are 0.04%, without saying what they are 0.04% of.
Edmund Contoski
A slightly later, and much quoted, version comes from Edmund Contoski in -
Not only is carbon dioxide's total greenhouse effect puny, mankind's contribution to it is minuscule. The overwhelming majority (97%) of carbon dioxide in the earth's atmosphere comes from nature, not from man. Volcanoes, swamps, rice paddies, fallen leaves, and even insects and bacteria produce carbon dioxide, as well as methane. According to the journal Science (Nov. 5, 1982) , termites alone emit ten times more carbon dioxide than all the factories and automobiles in the world. Natural wetlands emit more greenhouse gases than all human activities combined. (If greenhouse warming is such a problem, why are we trying to save all the wetlands?) Geothermal activity in Yellowstone National Park emits ten times the carbon dioxide of a midsized coal-burning power plant, and volcanoes emit hundreds of times more. In fact, our atmosphere's composition is primarily the result of volcanic activity. There are about 100 active volcanoes today, mostly in remote locations, and we're living in a period of relatively low volcanic activity. There have been times when volcanic activity was ten times greater than in modern times. But by far the largest source of carbon dioxide emissions is the equatorial Pacific Ocean. It produces 72% of the earth's emissions of carbon dioxide, and the rest of the Pacific, the Atlantic, the Indian Ocean, and the other oceans also contribute.
This is from a very long article which throws claim after claim at the reader. It starts by claiming all the warming of the 20th century was wiped out in - an utterly ludicrous claim.
He also claims that 72% of all emissions come from the Pacific ocean, a claim both wrong and incompatible with termites producing 40% of all emissions.
But his claim about termites is weaker than others, he only says termites emit ten times all the factories and automobiles in the world
, not all emissions from fossil fuel.
The Science
Contoski does at least provide a source - Science (Nov. 5, 1982). The article in question is Termites: A Potentially Large Source of Atmospheric Methane, Carbon Dioxide, and Molecular Hydrogen by P. R. Zimmerman et al.
This article seems to be the only paper ever cited as evidence that termites produce 10 times as much CO2 as humans. But there are a couple of problems using it as evidence:
- It doesn't support the claim.
- It's probably wrong.
The full article is behind a pay wall, but the abstract states:
The figure of 5 x 1016 grams of carbon dioxide is 50 Gt of CO2. This is less than twice current human emissions from fossil fuel, and around 2.5 times as much as human emissions in 1982 when the article was published; nothing like 10 times human emissions.Termites may emit large quantities of methane, carbon dioxide, and molecular hydrogen into the atmosphere. Global annual emissions calculated from laboratory measurements could reach 1.5 x 1014 grams of methane and 5 x 1016 grams of carbon dioxide. As much as 2 x 1014 grams of molecular hydrogen may also be produced. Field measurements of methane emissions from two termite nests in Guatemala corroborated the laboratory results. The largest emissions should occur in tropical areas disturbed by human activities.
It's accuracy was called into question as soon as it was published, even by the authors.
The Sydney Morning Herald quoted the authors as
saying, ... actual gas production may vary from their estimates by a factor of two.
and quotes Dr Pearman of CSIRO saying that as far as methane output was concerned
A couple of years after it's initial publication, Science published this letter from N. M. Collins and T. G. Wood, saying... the first impression was that the production rate on a global scale was about 10 times less than that reported in Science.
We do not question their laboratory experiments, but we are critical of their extrapolations of gas emissions (calculated from food consumption) to a global scale. Our appraisal of the available data indicates that gas emissions by termites was overestimated by at least one order of magnitude.
Since 1982 there have been other papers giving much lower estimates for termite emissions - agreeing with the claim that Zimmerman et al were out by a factor of 10.
In there was a paper in the Journal of Geophysical Research called The influence of termites on atmospheric trace gases: CH4, CO2, CHCl3, N2O, CO, H2, and light hydrocarbons (M. A. K. Khalil et al which put the global termite emissions of CO2 at 4 Gt per year.
Then in , we have research from M. G. Sanderson which gave termites a global CO2 emission rate of just 3.5 Gt per year (± 0.7 Gt per year).
A global database describing the geographical distribution of the biomass of termites and their emissions of methane and carbon dioxide has been constructed. Termite biomasses were assigned to various ecosystems using published measurements and a recent high-resolution (10' × 10') database of vegetation categories. The assigned biomasses were then combined with literature measurements of fluxes of methane and carbon dioxide from termites and extrapolated to give global emission estimates for each gas. The global emissions of methane and carbon dioxide are 19.7 ± 1.5 and 3500 ± 700 Mt yr-1, respectively (1 Mt = 1012 g) . These emissions contribute approximately 4% and 2%, respectively, to the total global fluxes of these gases.
That puts termite emissions at not much more than a tenth of all human emissions.
Incidentally, the figure of 2% of global fluxes
is misleading as they are comparing termite emissions against net land emissions.
Compared with total global emissions their figure is more like 0.5% for termites, compared with around 4% for humans.
Here's a graph comparing the different estimates for annual termite emissions along with that claimed by Corbyn. The dotted line shows 29 Gt, which is the value given for all human emissions in the IPCC's 4th report.
Dixy Lee Ray
So where did this myth originate? I don't know for certain, but the earliest record I could find is in a book called Trashing the Planet by Dixy Lee Ray. Published in this book, subtitled How Science Can Help Us Deal With Acid Rain, Depletion of the Ozone, and Nuclear Waste (among Other Things) is something of a blueprint for arguments made against environmental concerns, including global warming. The quote in question says:
The largest source of greenhouse gas may well be termites, whose digestive activities are responsible for about 50 billion tons of CO2 and methane annually. This is 10 times more than the present world production of CO2 from burning fossil fuel.
It's a garbled claim as it mixes CO2 and methane, but the figure of 50 billion tons (50 Gt) suggests it comes from the Zimmerman paper.
Given that this book was written only 8 years after the Science paper, and given that this passage was mentioned in several book reviews on publication, I think it's quite possible that Dixy Lee Ray is the originator of this zombie statistic.
Incidentally, Trashing the Planet, to give it its full title, was responsible, for more than the myth about termites. See The Volcano Gambit for another misunderstanding starting with an article in Science.
As to why Dixy Lee Ray made the mistake in the first place, I don't know. But I do have a very tentative theory - I wonder if it might have come from a confusion of different units used in measuring carbon. Carbon emissions can be described either as the mass of carbon-dioxide (CO2), or as the mass of carbon (C). This can be a big source of confusion, as Joe Romm explains. For this and the previous article I've tried to be consistent and convert all measurements into gigatons of CO2. But many sources measure emissions in mass of carbon - it's a simple process to convert the mass of carbon to the equivalent mass of carbon-dioxide, simply multiply by 3.67. Now, if you look at estimates for human emissions at the start of the 80s, this would have been around 5 Gt of Carbon. If you were not paying sufficient attention you could easily think the figure quoted in the Science paper (50 Gt of CO2) was ten times that of human emissions (5 Gt of C).
The real issue with the termite myth is not how it started, but how it has been perpetuated by people endlessly repeating other's mistakes. They
- Do not check the original source
- Do not check the figures
- Do not consider if human emissions have changed
- Do not ask if there are any estimates that contradict their claims
- Do not ask how termite emissions could be changing
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