Dozen lesser-known chemicals have strong impact on climate change

Science Daily: A new study indicates that major chemicals most often cited as leading causes of climate change, such as carbon dioxide and methane, are outclassed in their warming potential by compounds receiving less attention.

Purdue University and NASA examined more than a dozen chemicals, most of which are generated by humans, and have developed a blueprint for the underlying molecular machinery of global warming. The results appear in a special edition of the American Chemical Society's Journal of Physical Chemistry A, released Nov. 12.

The compounds, which contain fluorine atoms, are far more efficient at blocking radiation in the "atmospheric window," said Purdue Professor Joseph Francisco, who helped author the study. The atmospheric window is the frequency in the infrared region through which radiation from Earth is released into space, helping to cool the planet. When that radiation is trapped instead of being released, a "greenhouse effect" results, warming the globe. Most of the chemicals in question are used industrially, he said.
NASA scientist Timothy Lee, lead author of the study with Francisco and NASA postdoctoral fellow Partha Bera, characterized the fluorinated compounds as having the potential to quickly slam the atmospheric window shut, as opposed to gradually easing it shut like carbon dioxide.

In the results, chemicals such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur and nitrogen fluorides stood out in their warming potential because of their efficiency to trap radiation in the atmospheric window. "It's actually rather stark," said Francisco, a Purdue chemistry and earth and atmospheric sciences professor, whose research focuses on the chemistry of molecules in the atmosphere.

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, Francisco said….

Echocardiograph showing dilatation of the left ventricle in the acute phase. (B) Resolution of left ventricular function on repeat echocardiograph 6 days later. Perfluorocarbons are used in contrast-enhanced ultrasound to improve signal backscatter, just to show you a use that you hadn't thought of yet. Image by Tara C Gangadhar, Elisabeth Von der Lohe, Stephen G Sawada and Paul R Helft, Wikmedia Commons, under the Creative Commons Attribution 2.0 License