Man Made Global Warming

Several years ago I became curious about global warming, wondering if it was true as some say or a scam as others say. I have a Master's degree in engineering with specializing in heat transfer and fluid dynamics, so I knew I could understand most of the science and come to a decision myself.

My first stop was the claim that 97% of scientists agree that man is causing global warming, I wondered about the origin of this statistic. One source of this number is a paper published in 2013 [“Quantifying the consensus on anthropogenic global warming in the scientific literature”, John Cook, Dana Nuccitelli, Sarah A. Green, Mark Richardson, Bärbel Winkler, Rob Painting, Robert Way, Peter Jacobs, and Andrew Skuce, IOP Publishing, Environmental Research Letters, 2013]. In the study, the team identified 11,944 papers that had been written referencing “global warming” or “global climate change”. Criteria were identified to sort the papers into categories as to whether or not they took a stand on man causing global warming and whether the author believe man was causing global warming. The abstract or summary for these papers were reviewed against the criteria. After the review it was found that 66.4% (roughly two thirds) of the papers reviewed took no stand on man-made global warming. Of the third of the papers remaining 97.2% did credit man with adding to global warming. Another way of phrasing this statistic is that two thirds of scientist researching global warming do not advocate that man is causing global warming.

After this I made some simple mathematical models calculating the temperature of the earth using similar models found on the internet as a guide. These models showed that without the greenhouse effect of our atmosphere, the earth is a much cooler planet. The greenhouse effect is critical to maintain the temperatures we currently have. The most important parameter in modeling this greenhouse effect is the ability of the air to absorb and emit energy. This parameter is called emissivity. The belief behind man made global warming is the additional carbon dioxide increases the ability of the atmosphere to absorb and trap energy.

From the news reports I had assumed that carbon dioxide was the most prominent greenhouse gas, when I started looking I quickly found that it wasn't even close. The most prominent greenhouse gas is water vapor. The concentration of water vapor in the atmosphere varies up to 5% on humid days and the concentration of carbon dioxide is less than 400 parts per million (0.04%). So there is potentially 125 times more water vapor in the air than carbon dioxide.

It's difficult to calculate the emissivity of air but a paper by Nasif Nahle [“Science Confirmed: Carbon Dioxide & Water Vapor Cool Earth’s Atmosphere”, Nasif Nahle, Principia Scientific International, November 20, 2013] did this for me. In this paper Nahle went through the calculations the emissivity contribution of water vapor was 0.4 and the emissivity due to carbon dioxide was 0.0017. Remember the emissivity is a measure of how the compound is able to trap energy and water vapor can trap more than 200 times the energy trapped by carbon dioxide. Nahle went on to calculate the emissivity of the combined gases and found the increasing the carbon dioxide actually decreased the emissivity. At this point it was becoming increasingly difficult for me to believe that carbon dioxide has a major impact on the temperature of the earth.

Another paper by John Eggert [An Unsettling Look at the Settled Science of Global Warming, John Eggert, P. Eng.] pointed out the fact that as the concentration of carbon dioxide increases there is a point that additional carbon dioxide has no impact. In effect, once all the energy is absorbed by the atmosphere there is no more to be absorbed. Eggert's paper indicates that over a concentration of 200 ppm, increases in carbon dioxide have no impact on global temperatures.

These pieces of information was enough for me to be convinced that increasing levels of carbon dioxide have no impact on global temperatures. I won't argue the facts that the glaciers are melting and with the increase use of hydrocarbons of the last century the levels of carbon dioxide have increased. I just don't believe the increase in carbon dioxide levels is causing the glaciers to melt.