Researchers Find Five Previously Undetected Greenhouse Gases

By Mark Leberfinger, Staff Writer
March 31, 2014; 2:48 AM ET
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Two new scientific research efforts have uncovered five new man-made greenhouse gases that may play a role in climate change and ozone depletion.

Increasing greenhouse gases trap additional heat in the lower atmosphere, which results in higher surface temperatures, Senior Meteorologist Brett Anderson said.

"Climate models certainly account for the increase in greenhouse gases," Anderson said. "The increase in greenhouse gases may be causing more extremes in global weather over the long term, such as heat waves, drought and heavy precipitation events. However, it is very difficult to blame any particular extreme event on climate change."

The discovery of three chlorofluorocarbons (CFCs) and one hydrochlorofluorocarbon (HCFC) were reported online March 9, 2014, in the journal "Nature Geoscience" by researchers from the United Kingdom, Germany, Australia, France and the Netherlands.

"We were certainly surprised to find so many previously undetected gases out there, and we keep finding more," Johannes C. Laube of the University of East Anglia, Norwich, U.K., said.

At their current concentrations, the new gases do not pose a major threat to the ozone layer as they are tens to hundreds of times smaller than those of the known seven types of CFCs, which are still around, he said.

"What is worrying is the continuing increase of two of the gases, in particular that of CFC-113a, which is a) Much more dangerous to ozone than HCFC-133a, and b) has started to accelerate its increase after 2010. If such a trend were to continue, it would become a serious threat to the ozone layer within the next decade," Laube said.

Laube's team analyzed unpolluted air samples from Tasmania between 1978 and 2012 and air samples from polar firn snow from Greenland in 2008.

Polar firn snow is the hard snow on top of glaciers and can be up to 100 meters thick.

"As new snow falls on top of it, air bubbles are being trapped inside," Laube said. "If you drill into the firn, the deeper you get, the further you go back in time. At the bottom of the firn, the air can be up to 100 years old. So if we are interested in a particular gas in the atmosphere, this firn air allows us to reconstruct (using firn models) its temporal evolution over the last century."

The discovery of the new gases may have exposed a loophole in the "Montreal Protocol on Substances that Deplete the Ozone Layer."

It doesn't mean that the gases have been illegally introduced to the atmosphere in violation of the protocol, Laube said. Production of CFCs have been banned with limited exceptions since 2010, while some production of HCFCs continue.

"Our research has so far focused on the overall concentrations and trends of these gases in the global atmosphere, so we haven't attempted to pinpoint sources yet," Laube said. "We can currently only speculate on which are the major usages, but have found a few indications."

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CFC-112 and CFC-112a have been used for cleaning electronic components (e.g. for wax removal), CFC-113a is a feedstock to produce the insecticides cyhalothrin and tefluthrin, and both CFC-113a and HCFC-133a are intermediates for the production of chemicals used in air conditioning, he said.

Both types of gases deplete the ozone layer, a major contributor to climate change.

The other compound, perfluorotributylamine (PFTBA), a perfluoroalkyl amine, was discovered by researchers at the University of Toronto, Memorial University of Newfoundland and the Ford Motor Co.

That finding was published in late November 2013 in the journal "Geophysical Research Letters," a journal of the American Geophysical Union.

PFTBA is used as a coolant, the same broad class of compounds that includes chemicals such as chlorofluorocarbons. It is primarily used in industrial applications, Cora J. Young of the Memorial University of Newfoundland said.

This Jan. 23, 2013, file photo, shows a poor air quality sign is posted over a highway, in Salt Lake City. A new government report released Jan. 13, 2014, says energy-related carbon dioxide pollution increased slightly in 2013 after declining for several years in a row. (AP Photo/Rick Bowmer, File)

The discovery came after researchers noticed the chemical being used as a coolant in a piece of scientific equipment.

"By looking at its chemical structure, we hypothesized that it would be a strong greenhouse gas," Young said. "We then did some experiments to confirm this and set about looking for it in air samples.

We detected PFTBA in air samples that we collected in and around the city of Toronto."

The coolant, which is still being produced, is not regulated under the Montreal Protocol.

Because its main environmental impact is as a greenhouse gas, regulation would most likely come from climate change initiatives, Young said.

PFTBA has the greatest climate effect per molecule of any greenhouse gas that can be measured in the atmosphere, a very harmful impact, Young said.

"Global warming potential is one measure of the strength of a greenhouse gas. Carbon dioxide is defined as having a global warming potential of 1. Thus, for equal masses emitted of carbon dioxide and PFTBA, PFTBA will have a climate effect 7,100 times greater over 100 years," she said.

Carbon dioxide is emitted in masses far exceeding PFTBA, so that even though the impact per mass is much smaller, the overall climate impact of carbon dioxide is much larger, she said.


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