Ozone

December 06, 2021

While I have heard about the depletion of the ozone layer many times, it still shocks me when it is presented on my news feeds.  This morning I received notification the hole in the Arctic layer was being explored to gain better understanding on the phenomena and what might be done to reverse the trend.  Scientists have been tracking depletion of the ozone layer over the last fifty years and have known of the holes that open above the stratosphere (upper layer of the atmosphere).  When I looked online, I found there was not just one hole but two.  Both the Arctic and Antarctic have holes that appear during their respective winters and then slowly close as spring and summer arrive.  The problem was that these holes seem to be getting bigger and lasting longer.

My feed spoke of the Arctic hole in the ozone because this was a relatively new phenomenon.  The unusually large hole that opened in the ozone layer over the Arctic in 2020 seems to have been triggered by record-breaking winter temperatures in the North Pacific Ocean.  The hole encompassed nearly the entire ozone layer overhead but closed in early spring.  Scientists say there is a chance the hole in the ozone could form a lot more frequently in the future.  Plugging satellite data into a series of simulations, researchers have found high sea surface temperatures in the North Pacific have the power to lower the temperature of the Arctic’s westerly winds.  These high winds blow through winter into spring, and if they grow cold enough for long enough, they can trigger the formation of polar clouds in the stratosphere.  These clouds are a key ingredient in the ozone depletion process.

The “normal” ozone hole is a thinning of the ozone layer in the stratosphere above Antarctica that happens every September.  Chemically active forms of chlorine and bromine derived from human-produced compounds are released during reactions on high-altitude polar clouds.  The reactive chlorine and bromine then initiate ozone-destroying reactions as the sun rises in the Antarctic at the end of winter.  The 2021 Antarctic ozone hole reached its maximum on October 7 and ranks as the 13th-largest hole since 1979.  This year’s ozone hole developed as a colder than usual Southern Hemisphere winter led to a deep and larger-than-average ozone hole.  This will likely last into November or early December.  “Without a Montreal Protocol, it would have been much larger,” said Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. 

Thoughts:  The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out production of substances responsible for ozone depletion.  The Protocol was agreed to on 16 September 1987 and entered into force on 1 January 1989.  The Protocol has undergone nine revisions since being enacted.  As a result of the international agreement, the ozone hole in Antarctica is slowly recovering, and projections indicate the ozone layer will return to 1980 levels between 2050 and 2070.  The widespread adoption and implementation has been hailed as an example of international co-operation.  Global cooperation is possible once the public is convinced of the imminent risks.  A global pandemic is apparently not risky enough.  Follow the science.  Change is coming and it starts with you.