What is the Scientific Basis of Climate Change?

Several weeks ago we offered a link to a paper issued by the Pontifical Academy of Sciences and the Pontifical Academy of Social Sciences discussing climate change issues – Climate Change and the Common Good. One of the scientists who serves as a member of the Pontifical Academy of Science is Veerabhadran (Ram) Ramanathan.

Dr. Ram has given the MCC permission to reprint a summary of a position paper he wrote entitled: “The Two Worlds Approach to Mitigating Climate Change: The Top One Billion and the Bottom Three Billion.” In this and future updates we will re-print various sections of this summary document.

The Greenhouse Blanket:  The first question I am asked by the public is:

How does the colorless gas from my tail pipe of my car lead to heat waves, droughts, floods, severe storms, melting glaciers and finally sea level rise worldwide?

When we burn fossil fuels, the carbon in the fuel combines with oxygen in the air to form carbon dioxide. Once in the air, about half of the tailpipe emissions stay in the air for 100 years and about a quarter stays for over thousand years. Because of the long life of the potent carbon dioxide molecule, it covers the planet like a blanket. This has been going on since the ushering of the fossil fuel age by James Watts through his improved steam engine in the 1770s. About 1000 billion tons (Trillion) of this gas has accumulated in the blanket by now. Just like a blanket keeps us warm on a cold night by trapping our body heat, this blanket traps the heat from the surface and the atmosphere and warms both the surface and the atmosphere. Beyond tail pipes of cars, almost all human activities require energy released by the burning of fossil fuels. One notable exception is the poorest three billion, who still cannot afford fossil fuels even for basic activity such as cooking.

The Physics of Global Warming: The amount of heat trapped is determined by the quantum mechanics of the Carbon dioxide molecule and by the thickness of the blanket, which is about 1000 billion tons now. The Swedish Nobelist, Svante Arrehnius, worked out the science of the greenhouse effect of the Carbon-dioxide molecule and its global warming in detail 119 years ago. A detailed review of Arrehnius’ work to mark the hundredth anniversary of this path-breaking study was commissioned by the Swedish Academy of Sciences (Ramanathan and Vogelmann, 1997; all references are listed at the end of this paper). Many refinements to the Arrhenius’ theory have been made in the intervening century but the underlying science of Arrhenius work still stands firm, which is, that the climate system is very sensitive to increases in carbon dioxide and other greenhouse gases.

For nearly 75 years scientists believed that carbon dioxide was the only climate warming pollutant. This view changed dramatically with the publication of a study in 1975 (Ramanathan, 1975), which identified the refrigerant CFCs as a super greenhouse gas. This study showed that the addition of one molecule has the same warming effect as the addition of over 10,000 molecules of carbon dioxide. Soon, many other man made warming gases were identified, and as of now CFCs and the other warming gases are contributing as much as carbon dioxide. The problem became doubly more important.

Stay tuned for more next week!

 

Posted: June 19, 2015

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