Bacteria Responsible for Climate Change?

The scientific community is in the midst of one of the strangest controversies. Scientists affirm that climate change is caused by bacteria that use nitrogen and not the carbon dioxide emissions generated by human activities. Did the Intergovernmental Panel on Climate Change (IPCC) fail to take into account a key element in its models?

George V. Chilingar (Department of Civil and Environmental Engineering, University of Southern California) is one of the researchers who support this theory with O. G. Sorokhtin and L. F. Khilyuk. He was an adviser to Ronald Reagan and the United Nations. Moreover, he says that he “advised President George W. Bush not to sign the Kyoto Protocol.” He also states that “George A. Olah, a winner of the Nobel Prize in chemistry, is in agreement with [their] theory.”

O. G. Sorokhtin (Institute of Oceanology of the Russian Academy of Sciences, Moscow)

L. F. Khilyuk (Department of Civil and Environmental Engineering, University of Southern California)

“The hypothesis of current global warming resulting from the increased emission of greenhouse gases into the atmosphere is a myth. Humans are not responsible for the increase in the global surface temperature of 1°F (0.56°C) during the past century and one should explain this increase by natural forces heating the atmosphere,” [1]argue Sorokhtin, Chilingar, and Khilyuk. These authors propose a model that they call the adiabatic theory of the greenhouse effect. According to the latter, “the contemporary global warming, which started in the 17th century (i.e. long before the Industrial Revolution), probably is temporary and determined by the fluctuations in the solar activity.”

This graph, presented by these scientists, is supposed to show the correlation between the temperature change and solar activity.

“Contemporary global warming is developed on the background of general long-term climatic cooling. A new ice age had begun.” In the authors’ opinion, in 400 million years, all continents at moderate latitudes will be covered by glaciers. “At the equatorial belt, the elevated regions will be covered by ice.”This cooling would be caused by bacteria that consume nitrogen, the main constituent of our atmosphere (oxygen represents only 21% of the composition of air). If nitrogen was removed from the atmosphere, this would reduce the pressure of the latter. When the pressure of a gas drops, its temperature decreases—this characteristic of gas is used to generate cold in refrigerators. In our case, this would therefore lead to a cooling of Earth. According to these researchers, past ice ages were also generated by such phenomena related to bacterial activities. Conversely, warmer periods may have been brought about by an increase in atmospheric pressure, for example by an adding of oxygen by plants.

THE END OF LIFE ON EARTH
However, according to this model, in 600 million years, this cold period will come to an end. Oxygen created during the formation of the Earth’s core would no longer be incorporated in the iron contained in our planet’s mantle, the latter being totally “saturated” by this gas. So this oxygen would go in the atmosphere, making its pressure increase. A rise in the pressure of a gas leads to an increase in its temperature (this is the inverse of the case of the cooling of the atmosphere). In this case, the increase in atmospheric pressure would induce our planet’s temperature to rise to 400°C. The situation would continue to worsen: “In 1.5 billion years, the oceans will start boiling.” This would be the end of life on the blue planet.

WHERE IS THE CO2 COMING FROM?
In these authors’ opinion, the rise of the atmospheric carbon dioxide concentration is not the cause of an increase in temperature on Earth but its consequence! According to them, the oceans being the largest CO2 reservoir on Earth—they contain 92 times as much CO2 as the atmosphere—a temperature rise would make carbon dioxide escape from the water and go into the air. The idea is that the warmer a liquid is, the less dissolved gas it can contain. This law can be observed using two glasses and pouring hot water into one and cold water into the other. After a while, bubbles appear on the inner surface of the container that contains the hot water but not on the one with the cold water. These bubbles are made of gas that is “excluded“from the liquid, which can no longer contain it. According to these scientists, in such a situation on Earth, the oceans would therefore release huge quantities of CO2 into the atmosphere.

This graph, created at the Vostok station in Antarctica, charts the parallel change of the temperature and the atmospheric CO2 level. We notice on this chart that the temperature change always precedes the change in atmospheric carbon dioxide concentration.

THE COOLING EFFECT OF CO2
Once this carbon dioxide in the atmosphere, what consequences does it have? According to the Intergovernmental Panel on Climate Change (IPCC) carbon dioxide is a greenhouse gas and therefore induces a warming of the planet. In these researchers’ opinion, this is the contrary: it leads to a decrease in temperature! They state that if our atmosphere were replaced by another one entirely made of carbon dioxide, it would be colder. They reach this surprising conclusion considering that the elements constituting such an atmosphere (the molecules) are 1.5 times as heavy as the ones of air. These ”weighty” molecules have a strong propensity to absorb the sun’s heat by starting to move. These movements of molecules cause the gas to become less dense. This situation can be illustrated by bumper cars; during the night, when they are stationary, it is possible to park them side by side so that they do not take up a lot of room. But during the day, when they move, they use a larger area. It is the same with a gas, which expands once heated. In so doing, it becomes lighter—since it is less dense—and, according to these scientists, rises into the stratosphere, a layer of the atmosphere located between 10 and 50 km. (6-30 miles) above Earth’s surface. It would be a phenomenon similar to that used to operate hot-air balloons. In this case, the air inside the envelope is heated up. The gas expands and so becomes lighter than the one around it. Then it rises up, taking the basket along with it.

In their climate model, once this hot air is in the stratosphere, it cools by radiation, i.e. the heat of the gas changes into waves that go off into space. The hot air, after its ascent into the atmosphere, is replaced by cold air, which is heavier than the surrounding air and therefore goes down. Such movements of air masses are called convection. Thus, in these scientists’ opinion, carbon dioxide has a cooling effect by intensifying these movements.
Another gas that is generally regarded as warming the planet is methane. According to the authors, as in the case of CO2, it would have the effect of cooling the air through the same mechanism.

OTHER SCIENTISTS’ POINT OF VIEW
Regarding the possibility that nitrogen-consuming bacteria could lead to climate changes, Frank Poly, a scientist at the Laboratoire d’Ecologie Microbienne (Laboratory of Microbial Ecology) in Lyon (France), notes that “One must not lose sight of the fact that other theories linking climate to bacteria exist. For example, such microorganisms, also related to nitrogen, produce N2O, a greenhouse gas.” This phenomenon would therefore exert an opposite effect compared to the cooling generated by bacteria according to the mechanism set out by Chilingar, Sorokhtin, and Khilyuk. Bacteria are important in other processes, as in the creation of methane (a greenhouse gas) or dimethyl sulfide, an aerosol that has the curious property of inducing cloud formation. Werner Aeschbach-Hertig (Institute of Environmental Physics at the University of Heidelberg in Germany) works on reconstructions of past climates. He wrote an article in the Journal of Environmental Geology that contradicted the three scientists’ theory. He fears that this has enabled the authors to publish a new article to respond to it. “So I think now that it is better that I ignore these strange theories and concentrate on my scientific work. I don't want to answer questions about these obscure ideas,” he remarks. As for the famous skeptic Willie Wei-Hock Soon, he is also not convinced by the bacterial hypothesis. This astrophysicist at the Solar and Stellar Division of the Harvard-Smithionian Center for Astrophysics in the United States thinks that “The nitrogen-consuming bacteria probably play a role in climate. But is this phenomenon important?” To answer this question, we must go further in understanding the involvement of bacteria in this issue since no assessed estimate is provided in relation to this hypothesis at the present time by the scientists who support it. Nitrogen, carbon, phosphorus, oxygen, and sulfur are necessary for life. Among them, nitrogen has the greatest abundance in the atmosphere and the oceans. The amount of all this nitrogen is larger than that of the four other elements combined. But most of that nitrogen is in the air and cannot be used by the greater part of living beings. That’s where bacteria come in and transform nitrogen that is in the air into other forms that can be incorporated into organisms. For instance, the clover plant hosts such bacteria capable of converting nitrogen into protuberances on its roots.

Clover modifies nitrogen that is in the air. Thanks to this, living creatures like this ladybug can use this element. (Photo: Gius Cescu/http://www.fotocommunity.fr/pc/pc/mypics/979350)

MAN AND THE NITROGEN CYCLE

Since the nitrogen usable by organisms is quite scarce after all, in many environments plants stop developing due to the lack of this precious element. Regarding agriculture, mankind decided to remedy this problem by transforming its useless nitrogen into usable nitrogen in order to give it to cultivated plants so that they can better proliferate. But the quantities of this gas that must be modified through a chemical process (called Haber-Bosch) are such that human beings became a more significant player than nature in this transformation on the continents. This situation has various consequences, notably in terms of pollution. But the one that interests us here is that as the useless nitrogen is taken from the air, 100 million tons of this gas are captured through this process out of the atmosphere each year [2].

“A COMPLETE LACK OF UNDERSTANDING OF THE MECHANISMS”
Does this have an influence on climate according to the model proposed in this theory? It is relatively easy to realize that this is not the case. If we assume that during the past 100 years this amount of nitrogen has been taken out of the atmosphere annually, the total represents only one hundredth of the carbon dioxide added to the atmosphere by the emissions caused by human activities (this is in fact an overestimation for nitrogen since its transformation intensified in the last century). The authors of the theory estimate that the influence of anthropogenic emissions (generated by human activities) of CO2 on temperature is less than 0.03°C. They get this result by calculating the temperature rise according to the change in partial pressure of CO2 due to anthropogenic emissions according to the mechanism described above. Yet they “forget“ to take into account the greenhouse effect! In any event, it is difficult to see how it would be possible for anthropogenic emissions of CO2 to have a negligible effect on climate whereas a quantity of nitrogen at least 100 times smaller can lead to a cooling of Earth by taking into account the same phenomena. When they classify nitrogen-consuming bacteria into the “first-order climate drivers,” which they define as having “an importance 10,000 times greater than anthropogenic emissions of greenhouse gases,” we realize that the mistake is huge. “Changes in partial pressures caused by modifications of the atmosphere composition have a very small effect on climate,” explains Urs Neu, who conducts research on past climates within the Swiss Academy of Sciences. “There is a difference in temperature between the poles and the equator or between day and night even though the average atmospheric pressure between these geographic regions or different times of the day does not change,” continues this scientist, co-author of the book Climate Variability and Extremes during the Past 100 Years. Taking nitrogen up from the atmosphere does not significantly influence the Earth’s temperature, as this element is not a greenhouse gas. Gavin A. Schmidt, a climate modeler at the NASA Goddard Institute in New York City, agrees with this point of view and considers that the scientists who have put forward this hypothesis show “a total lack of understanding of the way the atmosphere works.”

CO2 AND CLIMATE
The bacterial hypothesis is not the only one formulated by Chilinar, Khilyuk, and Sorokhtin. What should we think about the idea that CO2 has the effect of cooling the atmosphere? Is the mechanism set out above real? Let’s recollect the theory: CO2 absorbs heat and so expands, becomes lighter, and rises into the stratosphere, where it cools by radiating out into space. Once cold, it descends in the atmosphere and refreshes it. “One of the problems with this theory is that a heated air parcel rises only if its temperature is higher than the one of the air that is around it,” explains Urs Neu. This is indeed what we saw in the example of the montgolfier: it rises up because the air is hotter inside the envelope than around it. “Because CO2 is relatively evenly distributed throughout the atmosphere, the warming due to the heat absorption of CO2 occurs everywhere.” adds the researcher. Given the fact that for convection phenomena to take place there must be parts of the atmosphere that are warmer than others to have mass differences, in such a case these air movements are nonexistent. Even if the convective processes described by the authors were real, hot air could not go to the stratosphere and cool there. Indeed, one might imagine intuitively that the more one goes up into the atmosphere, the more its temperature decreases. This is in fact not the case. The stratosphere is warmer than the top of the layer beneath it, the troposphere (inside which we are). “Because of that, convection phenomena cannot go through the boundary between these two layers,” underlines Urs Neu. Warm air arriving at this layer is colder than the surrounding air, so it is heavier than the air around it and stops its ascent.

OCEAN DEGASSING
We now come to the last point of this theory: is the rise in the atmospheric level of carbon dioxide caused by the ocean degassing resulting from the increase in temperature? Many factors lead to the refutation of this hypothesis. Techniques (isotopes C12/C13, radiocarbon) permit scientists to determine if the carbon is of natural origin or generated by combustion. One knows, thanks to these studies, that the increase of the atmospheric concentration of carbon dioxide is anthropogenic. The acidification of oceans, which is due to a rise in the quantity of CO2 that they contain, is also an indication pointing in the same direction. Furthermore, reconstructions of past climates carried out at Vostok Station in Antarctica (see graph above) show that in the transitions between glacial and interglacial periods, a temperature increase leads to a rise in atmospheric CO2. There is an 800-year latency between these two events. It is therefore not possible that the warming induces an increase in the atmospheric CO2 level in the current climate change. The authors also do calculations using Henry’s law, a physical law that allows connecting the concentration of a gas dissolved in a liquid and the pressure of this gas in the air. This leads them to the conclusion that CO2 has leaked out of the oceans, which would be consistent with the hypothesis of degassing. Yet only temperature variation is taken into account and not the change in the partial pressure of CO2. By introducing the latter, one can reach the opposite conclusion (depending on the chosen temperature). In addition, Urs Neu draws attention to the fact that Henry’s law is not valid for such considerations. “Many other processes and factors play a role in such a question. For example, there are colder areas in the oceans that can contain a lot of carbon dioxide. This cold water, denser than the one that surrounds it, will then descend into the ocean and therefore remove CO2 from the atmosphere.”

Yet even assuming that the calculations made by the scientists supporting the idea of degassing (using a temperature change of 1°C) are right, their own result contradicts their theory. Thus they come to the conclusion that the CO2 released by the oceans has induced an increase of 13.5 ppm (parts per million, unit of concentration) in the atmosphere. This would only explain a fraction of the actual rise, which is of 100 ppm. Among the first-order climate drivers also appear, according to Sorokthin, Chilingar, and Khilyuk, variations in solar activity. They justify this point of view with the graph correlating solar activity with the temperature on Earth (see above). Two scientists, Eigil Friis-Christensen and Knud Lassen, published a chart similar to the one presented by these researchers in the scientific magazine Science in 1991.

The 1991 graph. In blue: solar activity. In red: the terrestrial temperature.

Part of the scientific community remained skeptical of this paper. The reason for this was that some thought that the statistical treatment used had the effect of distorting the curve of solar activity for the recent periods. In 2000, new information permitted scientists to determine that the graph was wrong.

The corrected chart of 2000. Note that the correlation between solar activity and temperature no longer exists for the recent period of the curve.

Gavin A. Smith, who was named as one of the 50 leaders in science on a global scale by Scientific American magazine, thinks that “These authors’ theory does not make sense. It’s equivalent to writing a book about gravity and assigning all the effects to the sucking of a hypothetical giant turtle.”

                                                               Gaëtan Dübler

[1] The quotations in this part come from the book Global Warming and Global Cooling, Evolution of Climate on Hearth published by Elsevier and authored by the three above-mentioned scientists.

[2] For more information about the nitrogen cycle and man's influence on the latter, see for example Galloway et al., 2003, 1995; Burns and Hardy, 1975; Jaffe, 1992; McElroy et al., 1976; Schlesinger and Hartley, 1992; Stedman and Shetter, 1983; Söderlund and Svensson, 1976; Mackenzie, 1998.