Absorbing For Centuries, Oceans Could Start Emitting Ozone Depleting CFC Back Into The Atmosphere

The oceans around the world have huge reserves of many gases, including chlorofluorocarbons or CFCs. The ocean absorbs these gases from the atmosphere and draws them downward, where the gases can remain for centuries or even longer.

Chlorofluorocarbons or CFC gases are known to weaken the ozone layer. A study at the Massachusetts Institute of Technology (MIT), now identified as CFC-11 (a type of CFC gas), in oceanic flow that actually affects atmospheric concentrations.

Based on a new study, the MIT scientists has reported that oceans around the world, which have been absorbing the powerful ozone-damaging chemical they had long been absorbing -- for centuries -- are now emitting it.

According to a study by MIT scientists, the oceans will emit more CFC-11, a type of a CFC, back into the atmosphere than they absorb by 2075.

"Marine CFCs" originating from the sea have long been used as tracers to study ocean currents, but their effects on atmospheric concentrations have so far been considered to be negligible but now the new study has suggested that they do impact atmospheric concentrations.

The researchers project that by the year 2075, the oceans will emit more CFC-11 back into the atmosphere than they absorb, emitting detectable amounts of the chemical by 2130. 

Further, with increasing climate change, this shift will occur 10 years earlier. The emissions of CFC-11 from the ocean will effectively extend the chemical’s average residence time, causing it to linger five years longer in the atmosphere than it otherwise would. This may impact future estimations of CFC-11 emissions.

MIT scholar Susan Solomon says that by the time you enter the 22nd century, there will be a considerable part of this chemical coming out of the ocean. This is an interesting forecast and is expected to help future researchers understand what is happening.

Climate change will speed up this process. The team used the models to simulate a future with global warming of about 5 degrees Celsius by the year 2100, and found that climate change will advance the ocean’s shift to a source by 10 years and produce detectable levels of CFC-11 by 2140.

The research study's co-author, Peidong Wang, explains --

Generally, a colder ocean will absorb more CFCs. When climate change warms the ocean, it becomes a weaker reservoir and will also outgas a little faster.

"Even if there were no climate change, as CFCs decay in the atmosphere, eventually the ocean has too much relative to the atmosphere, and it will come back out,” Solomon adds. “Climate change, we think, will make that happen even sooner. But the switch is not dependent on climate change.”

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