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.

Al Gore Thwarted by Historians!

Is it true that our world is becoming chaotic because of climate change, as shown in Al Gore’s documentary An Inconvenient Truth? Are climatic extremes increasing today? What did past climates look like? Scientists think that the IPCC (Intergovernmental Panel on Climate Change) has been wrong on these issues. Depart on an amazing journey through time and ancient civilizations.

Yale University, United States, 1964: At the foot of the Harkness Tower, ferocious gusts of wind formed deep snowdrifts. According to legend, this building is the largest ever built of stone. There were icicles on the Aristotle, Euclid, and Shakespeare masks and statues, and from time to time members of campus secret societies crossed the park, going to meetings of their bizarre cults (Yale University is known for such groups, including Skull and Bones which have included among others both presidents Bush. This institution is also known for the education of this nation’s elite). These blurred silhouettes seemed at times to disappear in waves of wind and snow coming from the sky. When they were visible again, some were turning up the collar of their coat.

AN AMAZING DISCOVERY
Farther in the park, a porch could barely be made out, with steps indistinguishable in the snow and flanked by two lanterns forming a halo where snowflakes could be seen blowing in all directions. Above it, a man came and went in a room behind an illuminated window. He sat at his desk and took one of many tablets bearing cuneiform inscriptions piled around him. Running his hand delicately over the clay to remove a few grains of sand from a distant country, he recalled the story of its discovery. In 1933 in Syria, men wearing turbans and long coats, accompanied by camels, walked to a mound to bury a deceased Bedouin of their tribe. They began to dig and discovered a statue. When the French authorities, who were then in control of this nation, heard about it, archaeologists from the Louvre came to this site. Soon a temple was discovered, and then a whole city, that of Mari. In a palace with more than 260 rooms, 20 000 of these cuneiform tablets were found.The Professor of Assyriology and Babylonian literature at Yale University, whose name is William W. Hallo, then immersed himself in the mysterious succession of signs impressed by a hand four millennia ago (deciphering of cuneiform script has been known since 1851). Deciphering symbol after symbol, he soon realized that he had made a sensational discovery. The text recounted the itinerary of a trip in Mesopotamia (a geographical area between the Tigris and the Euphrates rivers, corresponding to present-day Iraq as well as parts of Syria, Turkey, and Iran. It was here where the first civilizations appeared, including the Sumerian, Babylonian, and Assyrian empires, between the 5th millennium and the 6th century BC). The text mentioned the capital, Tell Leilan, of a country whose existence was known only thanks to tablets that had been found in the ancient city of Babylon. It also indicated the distances between various points of a journey. Converted to a modern map, this itinerary permitted determination of the spot where this city, buried beneath the sands, should have been situated. But some archaeologists had doubts about its existence. "At the time nothing was definite,” remembers Harvey Weiss, a specialist in Middle Eastern civilizations at Yale University. Yet, in 1978, this archaeologist traveled to Syria, to the place indicated on the map by the text found in Mari. He started digging in a mound located between two trails and discovered a temple with columns magnificently decorated, and then found another. Later he found a 15 meter (50 foot)-high and 18 meter (60 foot)-thick surrounding wall. In 1981, Dr. Weiss explained to a New York Times journalist that he "hope[d] to finish the excavation by next summer" [i]. Since then decades have passed and the paper of the article has yellowed. But the archaeologist is still on his Tell Leilan site. The reason is that the site had yet to reveal secrets before Harvey Weiss could leave it. His excavations have shown that this city was suddenly abandoned. What prompted its inhabitants to move? The same appears to have happened in other cities of this Akkadian empire, which then collapsed.

THE EGYPTIAN EMPIRE TURNED TO ANARCHY

Even more disconcerting: the Old Kingdom of Egypt, which had built the pyramids, turned to anarchy at the same time as other civilizations in Palestine, Greece, and Crete. All reached their economic peak in 2 300 BC and then disappeared. "That was very strange. How could societies with different organizations and political structures all suffer the same fate at that particular time? Only an element having an interregional, hemispheric power could explain such a situation," says Harvey Weiss. He then looked for the cause of this situation. Soon clues started piling up; a drought was so severe in this region that even earthworms did not survive, as shown in analyses of soil samples. "In terms of strata, there is a layer of wind-blown dust in Tel Leilan as well as at many other places. This is a sign indicating dry soils and therefore a drastic rainfall reduction," adds this professor. Studies of pollen also point to a transformation of vegetation to plants adapted to arid conditions. "In Egypt, a decrease of 30 to 40% of the flow rate of the Nile River is observed, thanks to research conducted at both ends of this river,” explains the archaeologist. Indeed, this is the conclusion of studies of both the Nile River delta and East African lake levels, which constitute its source. Southern Mesopotamia was less affected by the drought thanks to its irrigated agriculture. There was an influx of climate refugees to this area. In an attempt to control this immigration, the empire built a wall 180 kilometers (112 miles) long.

A CURIOUS NASA REPORT
A NASA report about climate change and its implications for U.S. national security predicts that the United States will one day have to build such fortifications to hold back refugees [ii].

According to this document, important climatic modifications would cause food, water, and energy shortages. As recalled by archaeologist Steven LeBlanc of Harvard University, United States, from time immemorial, humans have engaged in warfare to obtain these elements.These conditions would quickly plunge China into serious political instability. Bangladesh would be uninhabitable. As a result of sea level rise, fresh water would be contaminated by salt water. A massive migration would take place, causing tensions in China and India as well as aggressive wars to obtain food, water, and energy. As predicted in the NASA report, in 2015 Russia and China would sign strategic agreements concerning energy resources in Siberia and Sakhalin (a Russian island, covered by forests, located in the Pacific Ocean and having significant oil, coal, and gas resources). In 2018 China would intervene in Kazakhstan to protect pipelines regularly attacked by rebels and criminals. In 2020 Europe's climate would be similar to that of present-day Siberia, and famines would start (in this report, the authors speculate that climate change could cause the disappearance of the Gulf Stream, an Atlantic Ocean current. This would lead, in their view, to cooler European climates).

"IN 2025, THE EUROPEAN UNION NEARS COLLAPSE."
The NASA report projects that in 2025, the European Union will nearly collapse. Chinese internal conditions will deteriorate dramatically, leading to a civil war. Chinese and U.S. naval forces will be in direct confrontation in the Persian Gulf. Australia and the United States would build defensive fortresses around their countries to protect them from starving immigrants from the Caribbean islands, Mexico, and South America. The United States and Canada would ally, the two countries becoming one. Nuclear weapons would proliferate. Pakistan, India, and China—all armed with nuclear weapons—would skirmish at their borders over arable land, a situation that could degenerate into even more disastrous war scenarios for humanity.But let’s go back to antiquity. Other societies have collapsed as a result of climate change. Four hundred years after the end of the Akkadian civilization, the same happened to the Tiwanaku civilization in the Andes. The reason again was lack of rain. The level of Lake Titicaca, located in this area, dropped by 10 meters (33 feet).The collapse of the Mayan civilization in the 9th century AD coincides with the longest and most severe drought of the millennium. The droughts related to these civilization collapses were more important than those that happened during the 19th and 20th centuries.

THE CLIMATE SINCE YEAR 1000

The stone here, far from representing its weight, expresses vertical momentum in columns that seem too light to bear the huge weight of the vaults suspended at dizzying heights. Through the stained glass windows, rays of light, made visible by specks of dust in the air, create colored patches of light on the floor. Men, seemingly tiny in this architecture of spectacular size, are now lifting onto their shoulders a support bearing a Black Virgin statue. The procession leaves the church, going from cool air to the scorching heat of the summer, from the shadowy light to the blazing sun, the penitents suddenly splashed by light. The clerics, wearing cassocks and richly ornamented cappa magna and holding banners and crucifix, which seem to sparkle in the sun, walk in front of the faithful. The procession crosses the town, arrives in the country, passes between fields with crops destroyed by the drought, and then arrives at the seaside. There, the Virgin statue is delicately lowered from its support and churchmen carry it to the water before bathing it. This is one of many French processions carried out during the Ancien Régime (period before the revolution) to satisfy the wrath of God, which was seen as the cause of extreme weather events. Other means were used, including prayer and witch hunts. Despite these efforts, the archives of this period mention many floods, with bridges swept away, and avalanches crushing houses. The most sophisticated database in the world in this domain exists in Switzerland. Named EuroClimHist, it contains more than 1.5 million entries. France is also in the process of establishing such a resource within the framework of the RENASEC (Les REfus de la NAture. Sociétés et Extrêmes Climatiques: Refusals of Nature. Society and Climatic Extremes) project. The documents dealing with climate information are listed, including harvest dates (grapes, hay, etc.), meteorological processions just described, and temperature measurements taken by the Paris Observatory since 1656. Sunspot variations are also taken into account, the latter reflecting activity of the sun. In France, departmental, municipal, and national records are sifted. "The registers of municipal deliberations are particularly useful," notes Emmanuel Garnier, the historian assigned to the OPHELIE (Observations PHEnologiques pour reconstruire le CLimat de l’Europe: Phenological Observations for Reconstructing Europe's Climate) and RENASEC projects.

The historian Emmanuel Garnier

Indeed, these documents were begun in 1450 and record, among other information, the weather. "It is because meteorological events have an economic impact. For example, in the case of drought, there was less water in the rivers, which means that it was no longer possible to use mills equipped with paddle wheels. So the grinding process halted and therefore flour was no longer on the market. Then, there was a risk of riot," continues the researcher. Administrative sources are also used, such as those concerning the bridges and roads, the forestry commission, and the navy. As part of the OPHELIE project, private individuals were also asked to send their own records related to climate. "We received many copies of diaries referring to climatic events,” remarks Emmanuel Garnier. These diaries were sometimes kept for 50 years (several members of a family would take turns making entries). In Switzerland, monks’ diaries have been searched. Another example of documents used by EuroClimHist are records of Stockholm’s port that exist from 1543 to 1893. As they indicate when a vessel entered or left the port, it is possible to deduce from them the periods during which the port was frozen.

"THERE WERE MORE HURRICANES IN THE 18TH CENTURY THAN DURING THE 20TH."
It would be wrong to imagine, as suggested in An Inconvenient Truth, that the Earth's climate has only recently been affected by extreme events because of global warming. Dr. Christian Pfister, a climate historian at the University of Berne in Switzerland, who has set up the EuroClimHist database, notes that "the largest Rhine River flood during the second millennium occurred in 1342. All the bridges were destroyed, and in Frankfurt the water surface was at roof level, 7 meters [23 feet] higher than the second most important flood in this area! "

Dr. Christian Pfister

The coldest winter during the last millennium occurred in 1364. "There was a 4-meter [13-foot]- thick layer of ice on the Rhone River," says the professor. Year 1473 was the hottest and driest during this millennium. "The conditions were such that all trees shed their leaves in August,” continues the historian. Hurricanes are also events that took place in the past. For example, in 1999, the French, Swiss, German, and Danish forests were devastated by a hurricane called Lothar. A very similar phenomenon happened in 1739 with about the same route and barometric pressure (measured at the Paris Observatory). In France the Fontainebleau castle was damaged, roofs were swept away, and trees fell. In a forest in Mulhouse 8 000 oaks collapsed. "To state that history repeats itself corresponds to a reality about the storms," says Emmanuel Garnier. While the idea of an increase in the number of storms as a result of global warming is often presented in the media, or even that storms are a very reliable climate change indicator, this professor thinks that "these assumptions are wrong. For instance there were more storms and hurricanes in the 18th century than in the 20th!” Christian Pfister confirms that "The past century is atypical by the fact that, in Central and Western Europe, few extreme weather events have occurred compared with other centuries." On the idea that the damage generated by the environment is more important today, Emmanuel Garnier thinks that "in many cases it was not climatic risk that increases but vulnerability." The concept explained in Al Gore’s documentary film that the climate is changing is not new. For example, in the 1820s–30s, the French mountains were less snowy. "There was then a consensus comparable to the present one, including official speeches, stating that there would be a disruption of the seasons, winters with less snow," notes Emmanuel Garnier. The climate change issue has been in vogue at other times, for example, during the 16th and 17th centuries. "We must be wary of the popular sense, because people forget climate history very quickly. After 20 years, a climatic catastrophe is blotted out. For example, few people today remember the 1976 heat wave!"

"IT WAS POSSIBLE TO CROSS THE RHONE RIVER ON FOOT"
Regarding violent weather events, if these studies do not confirm what one would have expected, another point is also disconcerting: temperature change. ”When I started my research, the view was that the last 500 years were marked by the Little Ice Age, i.e., a cold period that would have lasted from the early 14th century until 1850," explains Emmanuel Garnier. While he noticed cold periods, as shown for instance by the fact that the Seine and Rhone rivers froze, he also discovered very hot times with droughts. In 1480 in Lyon, the population was parched and died of heatstroke because of such a weather event. “The body of artisanal trades was decimated. A doubling of mortality was recorded from August to September while it was possible to cross the Rhone on foot,” observes the researcher (The Rhone is one of the major rivers in Europe). From 1705 to 1725 there were also scorching periods and terrible droughts lasting four or five months in the Paris region. In Languedoc-Roussillon (a region in southern France along the Mediterranean Sea) they lasted for one to two years. "These are phenomena similar to those seen today in the Sahel with problems of access to water and a desertification of the country," adds Emmanuel Garnier. This led to displacement and ethnic conflicts. For example, in 1612 in Narbonne, a city situated in the Languedoc-Roussillon, the Berber community—native to northern Africa—was accused of being the cause of a drought by generating the wrath of God before being expelled to Africa by boat.

"OUR VIEW OF PAST CLIMATES WILL HAVE TO CHANGE."
Christian Pfister confirms this point: "Our view of past climates will have to change. The IPCC (Intergovernmental Panel on Climate Change) reconstructions are based among others on dendrochronology(the study of patterns of growth of tree rings. For reconstructing past climates, it is estimated that the more the trunk grew between rings, the warmer it was). This technique gives information only about the time during which plants grow, i.e., 30–40% of climatic variation during a year. If one also has data for cold seasons, climate reconstruction will be different. "For example, in Western and Central Europe, the 12th century was warmer than what these curves show," adds Professor Pfister. We address the much talked-about controversy of the hockey stick, MBH 99. MBH is an abbreviation for the names of the three scientists who developed this curve, and 99 stands for the year of publication in the scientific journal Nature. In 2001, MBH 99 was included in the 3rd IPCC report, before being brought into the limelight.

The curve developed by Michael E. Mann et al. and published in Nature in 1999(MBH 99). The black curve shows 50-year average temperatures. The fluctuations around it are yearly temperatures. The grey region containing the curve represents the intervals in which real temperatures have a 95% chance of occurring. The red shows measurements by instruments (as opposed to temperature reconstructions).

MBH 99 as presented in the media, here from the front page of an important French daily dealing with economic and financial issues and published last year. Note that the graph ends in 2000. If we extrapolate this curve for 2009, it shows very hot temperatures...

Various criticisms, mostly unfounded, have been leveled against it regarding the statistical techniques used, the validity of some series resulting from dendrochronology, the number (deemed to be too low) of series used and their geographical distributions (sometimes described as not representative of the Northern Hemisphere).

Christian Pfister summarizes his views: "The MBH 99 curve probably has parts that do not represent actual temperatures for different times. The authors did not have the data necessary for such a study.” Other scientists have other opinions. For instance, Dr. Philip D. Jones, a climatologist at the University of East Anglia in the United Kingdom, who modeled curves similar to MBH 99, thinks that "new information will not significantly change our conclusions about past climates.” For this IPCC member, it is rather the use of archives about which one has to be wary: "The problem with these sources is that they tend to focus on the extremes but not on the small differences in average conditions.” He admits, however, that there may be questions regarding the quality of the data used in these reconstructions. "We must be careful about how we put datasets together, not only for surface measurements and weather balloons, but also for satellites.” Indeed, the latter are not designed to study variations over several decades because of changes in measurement instruments that have occurred over the past 50 years. For satellites, their orbits degenerate (i.e., they get closer to Earth) so they observe different parts of the globe during their rotation as time goes by. "Paradoxically, all these improvements, including the observations from space, create many problems," comments Dr. Jones.

"THERE ARE ALSO FINANCIAL ISSUES"
This controversy has also brought up another issue about studies of past climates: who can have access to the data? Though in science all information is normally made public so that other researchers can verify results, in this domain this policy is not necessarily implemented. For example, regarding temperature reconstructions for the last 1 000 years, two scientists, Warwick Hughes and Steve McIntyre, had difficulty obtaining the data from the scientist who had modeled the curves in question, Professor Philip Jones. He argues that it is not the universities’ role to make such data available before explaining that "[he] signed agreements with countries that stipulate that [he] would not give such information to third parties. Most European nations have restrictions on such dissemination of data." This is not the only case where scientists have had such problems. French researchers are struggling to access information from the EuroClimHist database. For his part, Christian Pfister explains that he invested 20 years of work in this study as well as personal money. "I want this to be credited to me within the framework of scientific publications," he remarks. As noted by Professor Garnier, there are also economic issues behind such information. "Insurance and reinsurance companies seek information for estimating the costs they will have to bear for damage generated by climate change.” (A reinsurance company acts as insurance for an insurance company. It guarantees a certain sum of the risk borne by insurance companies for a percentage of their premiums. This allows insurance companies to assume risks beyond the financial capacity covered by their funds and to avoid having to pay all the damages they insure in the case of a serious disaster and therefore to avoid bankruptcy in such a situation.) Yet this historian has decided that ''his'' database will be made entirely public, so it will then be possible for everyone to see past climatic extremes, for example, for the region where he or she lives. (I will give the link for the site of the database once it exists).
The criticisms expressed by these historians in relation to MBH 99 and changes in violent weather events do not mean that they are questioning the fact that the present climate change is a reality. Professor Pfister emphasizes that the past changes he observes are different from those he sees now: "In the Middle Ages, during warm periods, important changes often happened during the summers and winters, with colder and damper weather than today." In relation to antiquity, Harvey Weiss thinks that it was also different from the present situation. "These changes involve modifications in precipitation. Currently, there is an increase in temperature that is causing problems in terms of melting ice and rising sea levels. The current change is unique in the history of mankind. It is a frightening element."

AND THE FUTUR?
Beyond satisfying our curiosity to know about past climates, what's the point of such studies for our society? What makes these events interesting is that they document the resilience and vulnerability of large complex civilizations to environmental variability. Such societies have the capacity to cope with such problems, but they cannot adapt indefinitely. After a certain point, the established order collapses to make way for a new organization more in line with the new climate. "Climate changes forced the reorganization of many political structures," notes Harvey Weiss. We saw above that different societies, including the Mayans and the Egyptian Old Kingdom, collapsed when climate changes took place. More recent examples also exist, like the French Revolution. Spring 1788 was extremely hot, and thunderstorms devastated much of culture of the kingdom of France. "The consequences of this situation left a mark on the market from May, during the soudure, i.e., the transitional period between old and new crops. The Estates General was assembled by the king of France in 1789 to deal with the issue of a better representation of the people in politics. Its results were considered unsatisfactory, as evidenced by popular events linked to the high cost of wheat. Women marched on Versailles, taking by surprise the National Guard (police headed by Lafayette as commander in chief) and the National Assembly’s elected representatives (established during the Estates General, the National Constituent Assembly took as its mission to provide France with its first constitution). They were hungry and wanted food for themselves and their children," explains historian Emmanuel Garnier. Lafayette tried to contain the crowd and forced the king to return to Paris. Once the sovereign in the capital, this had the effect of significantly weakening his power, in that he was continually threatened by the riot, and this contributed to the collapse of the monarchy. Philip Jones also points out that the Vikings did not survive in northern and western Norway in the 14th and 15th centuries, probably because they failed to adapt to colder temperatures. Finally, the dinosaurs are not absent from this pattern! Alongside the famous meteorite hypothesis, another states that a colder period could have led to their extinction. "Humanity will have to adapt quickly, because climate change will certainly take place in the future faster than it did in the past. We should take this into account when designing buildings, crops, etc.," considers Dr. Jones. Renaud Crassous, a researcher at the Centre International de Recherche sur l’Environnement et le Développement (International Center for Research on Environment and Development) in France thinks that "In twenty years Earth will be affected by famines. We do not currently have sufficient stocks of food to cope with a climate change." Christian Pfister also observes that the worst impacts on populations occur when the change is not anticipated. "A climate change can happen very quickly, as was the case around 1300, when a colder climate suddenly settled. Our societies should have a greater safety margin in anticipation of such events. We are not currently ready." In the future three interdependent problems will arise: food, water, and energy shortages. “In addition, the price of fossil energy will increase. It is a very dangerous situation for a society,” continues the researcher. As for Emmanuel Garnier, he thinks that history has a role to play in the establishment of adaptations for land use, buildings, roads, etc.: "During the Ancien Régime, there were urban areas that were used for absorbing and spreading the floods. This no longer exists today," he remarks. Observer networks were set up, for example, upstream of a river to announce a flood. "In Lyon, debacles were feared when there was a very harsh winter because of pieces of ice coming from the Rhone Glacier in Switzerland. There were observers in the Alps who warned the city. Bridges peopled with residents and merchants were evacuated," he continues.

THE FUTURE: BACK TO THE PAST?
What will be the consequences of climate change on our societies? Emmanuel Garnier thinks that it could lead to organizations similar to those that existed in Europe during the Middle Ages! At that time disasters were taken care by religious aid, with secular payment beginning in France in 1650. Although the king was officially a Christian, being crowned in Reims by the pope, he gradually marginalized the Catholic Church. This occurred through specialized administrations that led investigations and paid compensations directly to the disaster victims. Gradually, climatic risk was no longer seen as a manifestation of the wrath of God but as a rational phenomenon that can be anticipated and handled. "Helping victims is a way to show that there is a central power and that it is better to rely on it than on local or religious authorities," explains Dr. Garnier. “This is a view that the United States’ federal government dropped beginning in the Reagan era. About Katrina—a hurricane that raged in the United States in 2005, where the most serious consequences were in New Orleans, Louisiana, which was then flooded—I was appalled when I saw the following scene: after 5 days, military trucks arrived with pastors from Christian fundamentalist sects. Instead of food they distributed bibles! The message was: if this area is flooded, it is because you are being punished by God. The interest for the central power is not to investigate climatic risk." For this scientist this is a turning point that also begins to emerge in France. "While in the 15th century there were flood markers, this practice has now been partially given up. As there is no flood marker, it is a way for the state to off-load the blame on elected representatives and owners in case of disaster." In his opinion, such a situation would lead the population to withdraw into their own communities, leading to a new social organization characterized by population segmentation, where individuals recognize only the authority of a small minority or group of people. At the level of nations, a lack of international solidarity could lead to regional wars motivated by the instinct of self-preservation. To put it bluntly, it would mean the return of societies similar to those of the Middle Ages. Knowing that these societies were also characterized by hunts for scapegoats, such as so-called witches, this situation can only send a shiver down the spine!
In terms of the energies used, this could not be more glorious. While one often speaks about trendy alternative energies such as wind turbines and solar panels, Hubert Kieken, a scientist at the Institut du Développement Durable et des Relations Internationales (Institute of Sustainable Development and International Relations) in France thinks that ”If there were no more oil in 10 years, the solution to the energy problem would be coal. It is possible to use this fuel to operate power plants and heaters and one can even create oil with it through a process called Fischer-Tropsch!” For this researcher, coal will retain a dominant share nuclear power in the next 50 years. The reason is that one needs to be able to quickly provide huge amounts of energy, for example, for China. The idea to use essentially nuclear energy in France works because this country is surrounded by nations with a different development pattern for their nuclear facilities. Thus France can export electricity to neighboring countries most of the time and import it during the winter. "This example is not reproducible on a large scale in other conditions. Moreover, with the current generation of nuclear power stations, we would soon face the problem of uranium depletion," concludes Dr. Kieken.

Gaëtan Dübler

[i] "Diggers Find Imperial City of Assyrians." The New York Times. October 18, 1981.

[ii] For more information, see http://oco.jpl.nasa.gov/pubs/Abrupt_Climate_Change_Scenario.pdf

How Was the Greenhouse Effect Discovered?

The greenhouse effect is central to the issue of global warming. But do you know how it was revealed? A look back at the history of climatology reveals unexpected elements.

On this evening of 1859, the rain fell on the cobblestones of Piccadilly Circus (a famous square located in London, England) on which long silvery reflections, emanating from the gaslights, stretched out. A carriage arriving from Shaftesbury Avenue broke the silence of the night. It took Regent Street, where it vanished, leaving only the fading echo of the noise of hooves in the maze of streets behind it. Nearby, on Albemarle Street, was a large building. Under the pediment, supported by heavy columns and on which letters carved into the stone read, “The Royal Institution of Great Britain,” a window was still lit despite the late hour. Under the flickering light of Bunsen burners (a piece of laboratory equipment that permits the production of a flame with gas), a scientist examined a strange machine that he had just finished assembling. He then went near its pipes and turned stopcocks; a hiss was heard, and carbon dioxide filled a long tube. The goal of this experiment was to solve one of the greatest mysteries of science at the time. It was known that Earth had gone through ice ages; how was it possible that the climate had altered so drastically? Science already had addressed this issue. In 1824, Joseph Fourier, a French physicist, proposed that these climate changes stemmed from changes in the composition of the terrestrial atmosphere. How did he reach this conclusion? Researchers knew that our planet, considering the heat that it receives from the sun, should be so cold that its entire surface could be covered with ice. It was therefore postulated that something in the atmosphere retained heat. Joseph Fourier carried out the following experiment: he put a box on which stood a window pane in the sun. He observed that the temperature rose inside this system. According to him, the atmosphere played the same role for the globe as the glass for the box. This experiment would later inspire the name of the phenomenon that he discovered: the greenhouse effect.

THE GREENHOUSE EFFECT IS ILL-NAMED!

Even so, this analogy is wrong. The reason that the temperature increases inside the box or the greenhouse is that the air is confined. One can realize this by opening a window in a greenhouse: the temperature then decreases until it is identical to the one outside. As regards the greenhouse effect of the atmosphere, it comes from the fact that the latter lets sunlight in but absorbs infrared radiation, as we shall see below. A pane has no such properties. The greenhouse effect is therefore ill-named!
However, this model was then accepted as valid; the question was how the atmosphere acts as a glass. The experiments developed by a scientist at the Royal Institution, John Tyndall, were precisely designed to address this issue.

John Tyndall

The first step was to extract gases constituting the air as oxygen, nitrogen, water vapor, and CO2. Carbon dioxide was obtained by distilling the air (distillation is a process that allows the separation of chemical substances by heating). A question that arises then is the following: the sun’s rays pass through the atmosphere and heat Earth. If this energy came from the universe, why does it not completely return there so that it warms the world? The reason for this is that the ground and oceans will cool by emitting what Joseph Fourier called “chaleur obscure” (”dark heat”). But the latter will be trapped by the atmosphere.

AN INVISIBLE LIGHT

What is this mysterious heat? In 1800, a discovery revealed its true nature. An English composer and astronomer, Sir Frederick William Herschel, was doing an experiment with a prism (a transparent object that disperses light into different colors. The same phenomenon can be observed with the raindrops when there is a rainbow).

Here we see a prism (the pyramid). On the right side, at the bottom, a ray of light hits it. A second beam is reflected and moves upward, whereas another part goes through it and is separated into colors.

By chance, a thermometer was placed on his desk, but beside the spectrum, i.e. the dispersion of light into colors. To this scientist’s great surprise, the temperature indicated by this instrument increased even though the light was not reaching it! Sir Herschel then realized that the thermometer was right next to the red part of the spectrum—which we see on the image at the top of the shaft of light transmitted through the prism. He deduced from that that there must be, beyond the red, an invisible light that carries heat. That is what we currently call infrared light. Though this light is not visible to humans, it is perceptible by other animals like certain snakes thanks to receptors located on their heads. Since Earth gives off the heat that it receives from the sun in the form of infrared light, John Tyndall had to use the latter to measure the heat absorption of the gases found in our atmosphere. How to generate such a light? The answer is surprisingly simple: any warm body gives out this light.

Your pet gives off light! Here, a cat seen in infrared. The light parts—the eyes, mouth, and ears—are those that emit the most, i.e. those that are warm or have significant heat losses.One also observes that its nose is relatively cold compared to the rest of the body.

This is the reason that some reptiles can detect infrared light: this enables them to perfectly locate their prey, even in the darkest night. But let’s get back to John Tyndall’s experiment. For the generation of infrared light, he would therefore create a warm body by pouring heated water into a container. Such an apparatus is called a Leslie’s cube because it had been developed by an English physicist, Sir John Leslie, in 1804.

View of the instruments used by John Tyndall for his experiment.

THE GREENHOUSE EFFECT MECHANISM CLARIFIED

In this picture, on the left-hand side of the piece of furniture on the left, we notice a cube, underneath which there is a Bunsen burner. This is a Leslie’s cube (the ”rod” striking out of it is a thermometer to measure the temperature of the water). A similar piece of equipment is mounted on the right side of the long horizontal tube. Inside the latter is the gas of which one wants to study the heat absorption. Its ends are sealed with a transparent material in order to confine the fluid of interest while letting the infrared light produced by the second Leslie’s cube go through it. We notice on the right-hand table an object composed of a stand and two cones. It is a thermopile. What is that? Inside it there is a special coil of wire that has the property, if one heats part of it up, of creating electricity. This type of battery has some applications today, such as to supply electricity to industrial processes requiring rapidly large quantities of energy. But this phenomenon is not used on a big scale because of its poor efficiency. In the experiment, the infrared light coming from the cubes will enter the thermopile through the cones. The greater the temperature difference between the two sides, the more electricity will be generated. It is connected by wires to another instrument placed on the stool; this is a galvanometer, a device capable of measuring electrical currents. So the more heat is absorbed by the gas inside the tube, the greater the temperature difference inside the thermopile and the more current it generates. Therefore, this equipment permits the measurement of the heat absorption of a gas. (Regarding the other instruments used for this experiment, one sees a screen on the right of the thermopile. The others are used to generate the fluids in question).
What were the results of this experiment? Among the perfectly translucent and invisible gases constituting our atmosphere, some absorb heat when infrared light goes through them. This is the case for water vapor and carbon dioxide. The mechanism of the greenhouse effect was thus clarified some 150 years ago!

TOWARDS A TEMPERATURE RISE?
Though this theory was seen at the time as a way to explain the past glaciations by variations of atmospheric CO2 concentration, it did not appear interesting regarding the contemporary climate. It was not until 72 years later, in 1896, that two Swedish scientists, a geologist, Arvid Högbom, and a chemist, Svante Arrhenius, made estimates and came to the conclusion that the CO2 generated by burning coal could lead to an increase in the terrestrial temperature. But this did not appear to be of concern given the fact that, with the quantities of carbon dioxide that were discharged, a long time would have been necessary to reach a problematic situation. Furthermore, for Nordic scientists, an increase in temperature would have been rather welcome. The idea arose of deliberately changing the Earth’s climate. The German physicist Walter Nernst, a Nobel Prize winner, fantasized about setting fire to useless coal seams in order to warm the climate!
In the years that followed, CO2 continued to be perceived as harmless. Indeed, many thought that the oceans could soak up the carbon dioxide that was released into the atmosphere. Soon another regulatory mechanism of nature was proposed: if the oceans contain more CO2 than the atmosphere, the same is true for living matter. It was therefore considered that even if the water could not absorb all the CO2 released, vegetation would take it up. The idea is that an increase in the atmospheric carbon dioxide level causes plants to grow faster. The latter using CO2 for photosynthesis, more plants would mean that more CO2 would disappear from the atmosphere and finally everything would return to normal. Yet in 1938, an English engineer named Guy Steward Callendar realized that the carbon dioxide concentration and the temperature increased. This discovery would revive scientific interest in this issue, and the measurements of atmospheric CO2 concentration would be improved progressively from 1960 onwards. Terrestrial temperature records would also get more sophisticated. Since the late 70s, satellites have been used for this task. New areas of research would open up such as the study of past atmospheric CO2 variations and their implications for the climate.

THE MAGNOLIA’S MEMORY
For instance, the 90s saw works dealing with plants that haven’t evolved much since the dinosaur era, such as the magnolia.

A magnolia flower. As these organisms evolved while bees did not exist, they are designed to be pollinated by beetles! (Beetles are insects, such as ladybugs, that are distinguished by their special wings. Today, this is the animal order that numbers the greatest number of species).

If these plants are exposed to significant levels of CO2, the shape of their leaves will be different. Fossils revealed such modifications. Given the fact that the climates of the dinosaur age were generally warmer than the present ones, this confirms that large carbon dioxide concentrations were connected with them.
The perception of the greenhouse effect has become more complex with the passing of time, though the one popularized by the media since the 60s is equivalent to the Joseph Fourier’s. More precisely, the infrared radiation given out by the soil will be gradually filtered during its passage through the atmosphere, so some of the light is absorbed by the air that thus heats up. The latter itself begins to give off infrared light in all directions, which in turn warms the surrounding air, etc. One can visualize the atmosphere as a juxtaposition of layers. The infrared light escapes into space only at the level of the uppermost layer of the troposphere, a layer of the atmosphere extending from the surface to an altitude of about 6 to 20 km (4-12 miles) depending on the geographic location.(The upper layers play an insignificant role in these phenomena.) What happens if we increase the CO2 level in the atmosphere? This last layer will contain more carbon dioxide, and thus infrared light will have more difficulty going through it. This reduces the amount of this light emitted by Earth. This layer therefore heats up, giving out infrared light that warms the layers beneath it, which themselves start to emit infrared light…This is how the whole atmosphere warms.
This model, which is used in the computer simulations of the temperature evolution in the future, shows that concerning warming, everything is conditional upon the uppermost layer of the stratosphere. The latter determines how much infrared light leaves the globe. The warming or the cooling of our blue planet depends on this layer.

Gaëtan Dübler