Oceans may emit more Ozone-Depleting Gases

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Oceans may emit more Ozone-Depleting Gases

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Oceans have a role: The world ocean is releasing ozone-depleting gases at a faster rate due to rising global temperatures, prompting scientists to warn of more ultraviolet radiation and a greater cancer risk. Chlorofluorocarbons, or CFCs, have slowly collected in deep ocean water for decades. The human-produced gas, commonly used for manufacturing aerosol sprays and refrigerants, is released into the atmosphere and then sucked into the ocean from surface wind, according to new research.
Role reversal: But the world’s oceans are on pace to reverse their role as a sink for CFCs, and researchers say hotter ocean temperatures due to climate change will make it happen faster. As gases such as CFCs degrade the stratospheric ozone layer, the Earth’s surface loses its protection against ultraviolet rays. Scientists warn that increased exposure to UVB rays causes increased risk of cancer, cataracts and immune deficiency disorders.
What changed: Since 2010, the Montreal Protocol—a global agreement to protect the stratosphere ozone layer by phasing out the production and consumption of ozone-depleting substances—has cut CFC emissions. Those already absorbed by the ocean are starting to be emitted as the atmosphere’s levels dip. But warmer water weakens oceans’ ability to be a reservoir for the potent ozone-consuming gas. Without climate change, the researchers predict that by 2075 oceans will emit more CFCs than they absorb. That shift could happen up to 10 years earlier with climate change.
Even without this: 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. Climate change will make that happen even sooner. But the switch is not dependent on climate change. This shift would happen first in the Northern Hemisphere—circulation there is expected to slow down, which leaves more gases in shallow waters, making it easier to escape into the atmosphere.

Climate change also can cause especially harmful CFCs, like CFC-11—a Class 1 ozone-depleting substance, according to EPA—to linger in the atmosphere longer, too.
CFC-11 also has a very long life in the stratosphere where it depletes the ozone—up to 55 years. CFC-12 can live up to 95 years. It can only be destroyed when it reaches high into the stratosphere, which takes awhile, meaning that CFCs are lasting longer in the atmosphere.
Many CFC detection models were pinning ocean CFC emissions on some countries near large ocean emission areas. From their estimates, current models have overpredicted illicit CFC-11 emissions by 10%. Findings could change policy around the Montreal Protocol, since many countries may not actually be violating the agreement.

Land or oceans: Some areas are actually producing CFCs illegally, like in the Shandong province in China. People might think these extra emissions are still coming from these countries, but it could just be increased emissions from the ocean. To decrease CFCs in the atmosphere, new policies need to look toward the land, not the sea. The amount of CFCs in the ocean is about 10% compared with CFCs stored on land. To prevent CFCs from getting into the air or water, he said scientists need to focus on developing technology that keeps land-based CFCs from escaping. It will be too technologically difficult to scrub CFCs from the oceans. CFCs are stored in chillers and building insulating foams, so when we tear down old buildings, that’s when new CFCs are released.
Knowledge centre:

CFCs - Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms. Individual CFC molecules are labeled with a unique numbering system. For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine (e.g. CCl3F as CFC-11). The best way to remember the system is the "rule of 90" or add 90 to the CFC number where the first digit is the number of carbon atoms (C), the second digit is the number of hydrogen atoms (H), and the third digit is number of the fluorine atoms (F). The total number of chlorine atoms (Cl) are calculated by the expression: Cl = 2(C+1) - H - F. In the example CFC-11 has one carbon, no hydrogen, one fluorine, and therefore 3 chlorine atoms. Refrigerators in the late 1800s and early 1900s used the toxic gases, ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2), as refrigerants. After a series of fatal accidents in the 1920s when methyl chloride leaked out of refrigerators, a search for a less toxic replacement begun as a collaborative effort of three American corporations- Frigidaire, General Motors, and Du Pont. CFCs were first synthesized in 1928 by Thomas Midgley, Jr. of General Motors, as safer chemicals for refrigerators used in large commercial appilications.
Ocean carbon sink - A carbon sink is a natural or artificial reservoir that absorbs and stores the atmosphere’s carbon with physical and biological mechanisms. Coal, oil, natural gases, methane hydrate and limestone are all examples of carbon sinks. After long processes and under certain conditions, these sinks have stored carbon for millennia. On the contrary, the use of these resources, considered as fossil, re-injects the carbon they hold into the atmosphere. Nowadays, other carbon sinks come into play: humus storing soils (such as peatlands), some vegetalizing environments (such as forming forests) and of course some biological and physical processes which take place in a marine environment. These processes form the well-known "ocean carbon pump". It is composed of two compartments: a biological pump which transfers surface carbon towards the seabed via the food web (it is stored there in the long term), and the physical pump which results from ocean circulation.
Montreal Protocol - The Montreal Protocol, finalized in 1987, is a global agreement to protect the stratospheric ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS). The United States ratified the Montreal Protocol in 1988 and has joined four subsequent amendments.
Kyoto Protocol - The Kyoto Protocol is a treaty created by the United Nations in 1997 that aimed to reduce carbon emissions worldwide, thereby combating global warming or climate change. It operationalizes the United Nations Framework Convention on Climate Change by committing industrialized countries and economies in transition to limit and reduce greenhouse gases (GHG) emissions in accordance with agreed individual targets.