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Carbon dioxide, public enemy No1?

By Pierre Jutras - posted Thursday, 11 February 2010

The 1997 Kyoto Protocol and the 2009 Copenhagen Summit identified carbon dioxide emissions and their effects on global climate as the main environmental threat to be tackled by modern societies, and environmental activists, such as Greenpeace, also put most of their energy into defeating the same beast. However, from a geologist’s perspective, this could be seen as an interesting paradox. In fact, carbon dioxide stands out as the “good guy” in the geological record, and problems show up when there is not enough of it in the atmosphere; not the contrary.

It is generally assumed that the current trend of global warming is detrimental to humanity and ecosystems in general. However, the geological record clearly indicates that the global ecosystem thrives during greenhouse ages and declines during ice ages, such as the one that we are presently experiencing. These observations on the long-term geological record are never part of the debate on global warming, which is usually constrained to the last few hundred years, or thousands of years at best.

Clearly, this does not bring enough perspective, as we have to go back 35 million years to get out of the current ice age, which started with the birth of an ice sheet on Antarctica. Since then, ecosystems have been experiencing tremendous stress due to the gradual deterioration of global climate. The current trend of global warming is but a small notch in a large scale trend of global cooling that started more than 100 million years ago. Prior to then, in Early Cretaceous times, the carbon dioxide levels of the atmosphere were more than six times higher than those of today, allowing life to flourish more than it ever had since the early Paleozoic (i.e., since the previous greenhouse age).


The current long-term cooling trend is caused by several orogenic events, which increase calcium and magnesium inputs to the oceans, from the erosion of continental crust, and which therefore promote the long-term storage of carbon in carbonate rocks (CaCO3 and CaMg(CO3)2). Most of these orogenic events are still ongoing (Himalayas, Alps, Rockies, Andes, etc.), and the current ice age is therefore destined to keep aggravating … unless we release a sufficient amount of the atmospheric carbon that is presently locked in fossil fuels …

Discrepancies between the geological record and global warming models

Most predictions on the effects of global warming are fatalistic. It seems to be the general consensus that ecosystems will suffer, although geological history states the contrary. Models also predict an increase in desertification, although greenhouse ages, such as that of the Cretaceous, seem to be devoid of deserts, which are features of ice ages.

One recurrent theme in alarmist global warming models is the prediction that there will be an increase in tropical storms. Again, the geological record suggests otherwise. For one thing, it is wrong to believe that CO2-induced global warming will result in a temperature increase for all regions of the globe. The absence of desert conditions during greenhouse ages suggests that profound changes occur in sub-tropical latitudes due to CO2-induced global warming, which may in fact result in substantial cooling for this specific latitudinal range.

Due to the dynamics of the Hadley cells, moisture is currently conveyed from sub-tropical (10° to 30°) to equatorial latitudes (0° to 10°), which explains why the former is mainly characterised by deserts while the latter hosts rain forest. Due to this, sub-tropical latitudes are currently much warmer than equatorial latitudes due to the greater cloud cover in the latter region, which allows less solar radiation to reach the ground. Somehow (perhaps due to the establishment of a less steep vertical gradient in temperature, which would effectively change the dynamics of Hadley cells), moisture and heat become better distributed during greenhouse ages and sub-tropical deserts cease to exist.

It is very likely that tropical storms would subside as well, as they are also the products of excessive heat in the dry, sub-tropical latitudes, whereas equatorial areas are devoid of them. The equatorial region is in effect a “shelter from the storm”, as suggested by a recent compilation by the National Oceanic and Atmospheric Administration (2005). In other words, although alarmist research on global warming pictures a greenhouse Earth as Dante’s Hell, the geological record rather presents it as a worldwide Garden of Eden, with no temperature extremes.

There is also reasonable grounds to doubt the predictions for an imminent (or even ongoing) substantial decrease in the volume of polar ice sheets, because the latter began to form when carbon dioxide levels were substantially higher than today (35 and 7 million years ago for Antarctica and Greenland, respectively), and because of their self-sustaining nature, due to their high albedo (reflectance). The geological record clearly indicates that ice-sheets can survive under a climate that is substantially warmer than the one in which they started to form. Human-induced global warming is presently far from bringing the climate to temperatures that would substantially exceed those of seven million years ago, and it is unlikely that it ever will.


Alarming footage of melting glacier fronts are in fact not alarming at all, as glacier fronts are always experiencing melting, even as they advance. Only the central portions of an ice-sheet are under conditions that allow the accumulation of snow and ice (accumulation zone), whereas its marginal portions are under a climate in which melting exceeds accumulation (ablation zone). Ice flows plastically from the accumulation zone to the ablation zone in response to gravity, but it does not form in the latter zone.

More alarming than the fact that climate models are not supported by the deep geological record is the fact that climate modelers are generally not aware of these discrepancies. There are no efforts being put forward to explain why human-induced increases in atmospheric carbon dioxide would stimulate desertification, whereas naturally induced increases did the contrary in the past, simply because climate modelers are generally not aware that previous greenhouse ages were devoid of deserts.

Because five-day weather predictions are still quite unreliable, although they can be tested every five days, 100-year climate predictions are hardly convincing. Testing them every 100 years is not very useful, and the geological record is therefore the only available ground on which to test them. However, this is clearly not being done, simply because climate modelers do not have a geological background, and because geologists have not been properly included in the debate on climate change.

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About the Author

Pierre Jutras is an associate professor of geology at Saint Mary's University, United States.

Creative Commons LicenseThis work is licensed under a Creative Commons License.

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