Climate change studies scientific

In an op-ed article (BDN, Dec. 4) titled “Global Warming Another Fantasy,” Doug Merrill argues global warming is a myth being propagated by scientists based on “discredited, pseudo-scientific computer models.” Let me assure readers that the global climate change field of study is based on fundamental principles of science.

Every one of us is taking part in the largest scientific experiment conducted by humankind: What happens when all the reduced carbon, primarily fossil fuel, produced over the past 500 million years in the Earth’s crust is burned in a mere 150-year time period?

From the chemical structure of fossil fuel, we know that every gram has an energy content of about 10 calories. The engine of growth for every industrial society is energy. The incredibly high standard of living that our country has achieved is based on the readily available energy content of fossil fuel. Scientific conservation laws dictate that during chemical reactions, substances are neither created nor destroyed. The reduced carbon in petroleum and coal is converted to carbon dioxide upon combustion, and energy is released.

The concern about environmental impacts of burning fossil fuel is not new. The great physical chemist Svante Arrhenius published a paper in 1896 detailing the chemical mechanism of how fossil fuel burning will increase global temperature. The Earth’s atmosphere is transparent to visible light from the sun, but absorbs a large fraction of infrared rays emitted from the Earth’s surface because of the matching between the molecular transition energy levels of carbon dioxide and infrared rays from the Earth’s surface. This adsorbed energy is reradiated in all directions, and those orientated back to Earth heat the Earth.

Further analysis of how changes to atmospheric composition will likely affect global climate is even more troubling than the well publicized carbon dioxide effect. The infrared rays emitted from the Earth’s surface have a wavelength between 4 and 24 micrometers. Infrared rays between 8 and 10 micrometers are not absorbed by either carbon dioxide or water vapor and thus pass through the atmosphere. However, this transparent region can be covered by other gases such as methane, chlorofluorocarbons and nitrous oxides. In fact, these gases have a much higher ratio of radiative heating than carbon dioxide on a per molecule basis.

This is due to carbon dioxide concentrations being high enough so that most of the infrared rays are already absorbed. Thus, any additional carbon dioxide will have a small impact on the total absorption of infrared rays. However, for the other greenhouse gases in the transparent window, their contribution to the total infrared rays absorbed is large since the infrared is likely not to have been previously adsorbed. Methane, nitrous oxide, and Freon are 20, 200 and 10,000 times more effective at heating up the atmosphere on a per-molecule basis, respectively, than carbon dioxide.

All of this is based on scientific fact. Doug Merrill is correct in stating that Earth is a rugged place. The whole Earth system is resilient and changes in some factors tend to be countered through feedback mechanisms to bring it back to some equilibrium state. It is a very intricate system with many linkages between both biotic and abiotic factors. The critics of global warming frequently like to state that scientists cannot show that anthropogenic carbon dioxide emission has led to warming of the Earth.

I am not a climate scientist, but I appreciate the great difficulty in establishing cause and effect in such a noisy and complex system as the Earth’s climate. Can it be proved right now that increased carbon dioxide levels has led to climate change? Probably not. But what does “proved” mean anyway? Chances are that the effects will be environmentally and social significant before it can “proved” in a legal or statistical way.

The potential changes brought on by fossil fuel burning are truly of global concern. Many of potential effects are unknown. Like many experiments I do in my laboratory with soil carbon, the results can be surprisingly different from those expected. It is likely that global systems display characteristics that are robust and sensitive to environmental perturbation. We are far into this global experiment. Should we blindly proceed and use fossil fuel without constraint? Our modern, industrialized society has become dependent on fossil fuel not only for its energy content, but also for its use as the chemical building block to many products.

The fossil fuel resource that was built up over millennia is dwindling fast, and society will be facing in the next century how to adjust to depletion of the vast energy and resource base it requires to support our current standard of living.

This, along with the environmental issues caused by our enormous energy demands, will have to be addressed worldwide by citizens and governments. Unfortunately, all of this is not a myth. It is a profound issue that will likely affect us and future generations in ways that will require difficult decisions.

Tsutomu Ohno, Ph.D., is an associate professor of plant and soil chemistry at the University of Maine.