GlobalShift

The Forgotten Chemicals In Global Warming

Most are aware of the role major chemicals, like carbon dioxide and methane, play in climate change. What you might not know about are the other chemicals that contribute to warming. Recently, Purdue University and NASA teamed up to study over a dozen chemicals, most of which are generated by humans, that receive little attention but whose potential to cause warming is big.

They even developed a blueprint for each chemical’s underlying molecular machinery and how they operate within a context of global warming; something which had not been done before. The researchers looked at list of more than a dozen chemicals considered to be warming agents by the Intergovernmental Panel on Climate Change (IPCC). The study used experimental observations and computer modeling using supercomputers from Purdue (seen in picture) and NASA. The goal was to determine which chemical and physical properties are most important in contributing to global warming.

Their results found that chemicals such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur fluorides, and nitrogen fluorides stood out in their warming potential. These compounds containing fluorine atoms are far more efficient at blocking radiation in, what the study called, an “atmospheric window”. The atmospheric window is the frequency in the infrared region of energy wavelengths, through which radiation from Earth is released into space, helping to cool the planet. When radiation is trapped instead of being released, we get the well-known “greenhouse effect”.

Fluorine atoms tend to be electro-negative, meaning they pull electrons to themselves. This makes molecular compounds that contain fluorine more efficient at absorbing radiation, which would otherwise flow out into space. The compounds also linger longer than carbon dioxide and other major global warming agents. Some of these chemicals don’t break down for thousands of years. The concern is that if emitted into the atmosphere, even in lower quantities, the chemicals might have a powerful cumulative effect over time.

Most of these particular culpable chemicals are used industrially. Both CFC’s and HFC’s are often used in aerosols, solvents, and refrigeration. HFC’s can fit under an umbrella of several commercial categories (like halocarbon, halogens, etc.) with use in the manufacturing of electronics, appliances, carpets, and many other things. They are often marketed under the name of HFO. PFC’s are also found in refrigeration and air-conditioning, but are in some cosmetics, as well as being used in many different medical procedures. All are also used as propellants in airplanes and jets.

Fluorinated compounds have been characterized as having the potential to quickly slam the atmospheric window shut, as opposed to gradually easing it shut like carbon dioxide. This one reason it was important to map the molecules involved. An understanding of how the chemicals contribute to climate change on a molecular scale affords the opportunity to create benign alternatives and to test new chemicals for their global warming capability before they go to market. We now have a rational basis for better design, which will make it easier for markets to move towards solving this problem. Already we are making strides towards alternative techniques that can be used in a/c and refrigeration. This is particularly critical because as of January 2010, one of the most commonly used coolants will begin being phased out of production as part of the Montreal Protocol.

Although current concentrations of some of these trace gases have been small compared to carbon dioxide, their concentration is on the rise. With current rates of increase, they will be important contributors in the future unless we find an alternative to their use. I’m sure that we will.