CO2, Methane Ousted as Worst Global Climate Change Chemicals

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Move over CO2—you’ve been ousted, along with methane, as the biggest offenders of global climate change. According to a new a study by Purdue University and NASA, the major chemicals most frequently cited as leading to climate change, namely carbon dioxide and methane, are actually outclassed in their warming potential by compounds receiving less attention. The majority of “greenhouse gases” are created by humans.

The results were discovered when researchers studied more than a dozen chemicals, or greenhouse gases as classified by their warming properties defined by the Intergovernmental Panel on Climate Change. From there, the team developed a blueprint for the underlying molecular machinery of global warming. The results appeared in the November 12, 2009 issue of the American Chemical Society’s Journal of Physical Chemistry, just in time for the convergence of world leaders in Copenhagen.

Maybe more amazing than the fact that we now have a global warming blueprint is that no one else has ever before mapped climate change; yet the U.S. is in the midst of passing global climate change policy. The original hope was to have legislation in place prior to Copenhagen but in the spirit of American politics, Republicans and Democrats can’t agree on one policy—the Republicans are supporting the Waxman-Markey Bill and the Democrats are pushing the Kerry-Boxer Bill.

The Purdue/NASA study combined results from experimental observations along with computer modeling. The goal of the project was to determine which chemical and physical properties are most detrimental in causing global warming.

It turns out that the compounds, which contain fluorine atoms, are far more efficient at blocking radiation in the “atmospheric window,” according to Purdue chemistry and earth and atmospheric sciences professor Joseph Francisco, a study co-author. NASA scientist Timothy Lee was lead author of the study with Francisco and NASA postdoctoral fellow Partha Bera.

Francisco explains that 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 the heat is trapped rather than released, a “greenhouse effect” occurs, and the planet becomes warmer. The majority of the chemicals that cause heat to be trapped are used by industries worldwide.

Based on the ability to trap radiation in the atmospheric window, chemicals such as sulfur and nitrogen flourides, perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), and chlorofluorocarbons (CFCs) stand out. Chemicals like CO2, while harmful, don’t close the atmospheric window as quickly as these other compounds making them more dangerous.

“It’s actually rather stark,” said Francisco, “but 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.”

“Now you have a rational design basis,” he said.

Not sure what some of these are? Stop using aerosol cans. CFC use has decreased with the discovery that they lead to the destruction of the ozone layer. However, HFCs and PFCs are widely used in air conditioning and in the manufacturing of carpets, appliances and electronics.

The study notes that, “Although current concentrations of some of these trace gases have been found to be substantially small compared to carbon dioxide, their concentration is on the rise. With the current rate of increase, they will be important contributors in the future, according to some models.”

So CO2 and methane are not in fact the worst chemicals, but fluorine-containing compounds are actually the worst. In addition, according to Lee, “The compounds also persist longer than carbon dioxide and other major global warming agents. The concern is that, even if emitted into the atmosphere in lower quantities, the chemicals might have a powerful cumulative effect over time. Some of these chemicals don’t break down for thousands of years.”

Well I sure hope that the auto industry is working in tandem with technology companies to replace these chemicals because I’d really like to keep my air conditioning… and car stereo… and TV…

 

Joanna Schroeder

Joanna is a writer and consultant specializing in renewable energy and sustainable agriculture issues.