The most of us Don’t think about ozone as we go about our daily lives. Still, this bright blue gas plays a big part in keeping our planet habitable. There is a layer of it in the Earth’s stratosphere, and it absorbs most of the ultraviolet radiation that comes from the sun. Without the ozone layer, UV radiation would severely damage most life on earth. What would happen if we had an ozone hole?
In 1985, scientists discovered an ozone hole — or more accurately, a depletion — in the ozone layer, particularly over southern regions of the world. This happens every September. The loss is largely due to chemically active forms of chlorine and bromine derived from human-made compounds in the atmosphere. They attach themselves to high polar clouds every southern winter.
Once there, they begin ozone-depleting reactions when the sun rises at the end of the Antarctic winter. These actions create the ozone hole. People living in the area are dealing with higher rates of sunburn, skin cancer and other conditions thanks to increased UV flow through the hole. And the damage isn’t limited to humans; Plants and animals on the surface and in marine ecosystems are also affected.
Today, the use of most ozone-depleting chemicals is banned or remains heavily regulated. This is thanks to the strict measures of the Montreal Protocol on Substances that Deplete the Ozone Layer. It’s an environmental treaty that regulates the production and consumption of nearly a hundred man-made chemicals that can deplete the ozone layer. The regulations and bans led to a slow restoration of the ozone layer.
NASA and NOAA investigate the ozone hole
The annual size of the Antarctic ozone hole is now about 23.2 million square kilometers. That’s slightly smaller than last year’s measurement and indicates the hole is continuing to shrink. Researchers from NASA and NOAA (the US National Oceanic and Atmospheric Administration) are detecting and measuring the growth and collapse of the ozone hole. They use instruments onboard the Aura, Suomi NPP and NOAA-20 satellites to monitor the hole’s growth and shrinkage. While it generally shrinks over time, there are occasional brief periods when the ozone hole is slightly larger than average. Satellite measurements are helping scientists understand more details about how and why the hole grows and shrinks seasonally.
“Over time, steady progress is being made and the hole is getting smaller,” said Paul Newman, chief scientist for earth sciences at NASA’s Goddard Space Flight Center. “We’re seeing some variability as the weather changes and other factors cause the numbers to wiggle slightly from day to day and week to week. But overall we see it decreasing over the past two decades. The elimination of ozone-depleting substances through the Montreal Protocol is shrinking the hole.”
Research into the ozone hole is a long-term process. It enables the best possible understanding of the interplay between the ozone layer, human activities and other effects. It requires special instruments to keep track of the different moving parts. For example, when the polar sun rises, scientists use a Dobsonian spectrophotometer to record the total amount of ozone between the Earth’s surface and the uppermost regions of the stratosphere. The Dobsonian is an optical instrument that helps scientists calculate a number called the “column ozone value.”
To give an idea of what the numbers are, the total column average around the world is about 300 Dobsonian units. On October 3, 2022, scientists recorded the lowest ozone level in the total column of 101 Dobsonian units over the South Pole. Back then, ozone was almost completely absent at altitudes between 14 and 21 kilometers (8 and 13 miles) – a pattern very similar to last year’s.
This is good news for people living at these latitudes, and also for people living at high altitudes who are also at risk from prolonged UV exposure. Continued regulation of ozone-depleting compounds should play a large role in reversing the damage done to our upper atmosphere.
This article was originally published on universe today by CAROLYN COLLINS PETERSEN. Read the original article here.