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Major climate deal to curb potent greenhouse gas

John Kerry Speaks on Montreal Protocol in Kigali, Rwanda
Credit: U.S. Department of State

Research first appeared in the early 1970s concerning how chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) contributed to the destruction of Earth’s protective ozone layer. At the time, CFCs were abundant in the developed world; commonly used in refrigeration, air conditioning, fire protection, aerospace, electronics, and agriculture.

Because of the unique and lethal threat posed by ozone depletion, nations from around the world came together on August 26, 1987 to ratify an international treaty known as the Montreal Protocol on Substances that Deplete the Ozone Layer. The treaty helps Earth’s protective ozone layer recover by phasing out these harmful synthetic substances.

[su_spoiler title=”Easy to understand explanation”]Through a series of chemical reactions, CFCs and HCFCs release chlorine atoms which act like pinballs of destruction leaving a smattering of broken ozone molecules in their wake.[/su_spoiler]

[su_spoiler title=”Not-so-easy to understand explanation! Skip if uncomfortable with chemistry. “]All substances regulated by the Montreal Protocol contain either chlorine or bromine. Natural processes maintain a delicate ozone-oxygen cycle in the stratosphere, but human-introduced CFCs interact in a destructive manner. In the stratosphere without the protection of the ozone layer, CFC molecules break up when receiving ultraviolet energy. Chlorine atoms are released and react with ozone molecules, taking one oxygen atom to form chlorine monoxide and leaving an ordinary oxygen molecule. Chlorine monoxide interacts with a free oxygen atom, which combines oxygen atoms and releases a free chlorine atom to again break apart an ozone molecule.[/su_spoiler]

During the phasing out of CFCs, hydrofluorocarbons (HFCs) became the gold standard replacement because they do not contain chlorine atoms and therefor do not pose a risk to the ozone. But there was another, slightly more pressing problem.

HFCs are an extremely potent greenhouse gas. They act like a heat trapping blanket around the planet when they enter the atmosphere. As developing markets grew and access to consumer products like air conditioners and refrigerators expanded, HFC use skyrocketed.

Once again, the world came together. This past Saturday, in the Rwandan capital of Kigali, the United Nations ratified an amendment to the Montreal Protocol to phase out HFC use in consumer and industrial products. The agreement will force a shift to safer substitutes for some of the planet’s most dangerous greenhouse gases.

The deal will reduce global HFC levels by between 80 and 85 percent by 2047. Scientists expect the measure to prevent nearly half a degree Celsius of warming by the end of the century, which will positively impact Michigan’s climate.

The agreement must still pass the United States Senate in order for the United States to enter the agreement as a binding member.

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