As the coronavirus pandemic causes shutdowns in major metropolitan centers worldwide, pollution levels in many areas are trending lower. The atmosphere is clearing up and residents of highly polluted cities are able to see their natural surroundings for the first time in decades. As the pandemic continues, life on the ground and in the air continues to change.
Just because our skies are clearing up doesn’t mean pollution’s effects are over. Chemicals that have been released into the atmosphere are still interacting with one another. For instance, common chemicals used in refrigerants contribute to ozone depletion, a phenomena currently being measured over the North Pole.
The Right Atmospheric Conditions Have Depleted the Ozone Layer Over the North Pole
A combination of atmospheric factors have led to the creation of the lowest levels of ozone in a decade over the Arctic. This hole in the ozone layer is caused by a polar vortex that traps cold air in the atmosphere above the Arctic. This frigid air leads to the accumulation of clouds that reach into the stratosphere, located 10-50 kilometers above the surface of the Earth.
These stratospheric clouds contain chlorofluorocarbons and hydrochlorofluorocarbons, both chemicals used in refrigerants. These particles interact with the ultraviolet rays coming into our atmosphere from the sun and release chlorine and bromine. Chlorine and bromine then interact with the ozone layer, breaking it down and causing a hole.
Ozone Depletion at Both Poles
The conditions currently causing the ozone depletion in the Northern Hemisphere are also present in the Southern Hemisphere. During the Southern Hemisphere’s spring, the ozone layer can be depleted by up to 70%. In some locations, the concentration of ozone in the atmosphere is zero. During the Northern Hemisphere’s spring, the same situation also occurs, albeit to a lesser extent.
Low Ozone Levels Measured at the North Pole
Winter temperatures in the Arctic tend to be warmer than the winter temperatures in Antarctica. This gives cold air and the chemicals in the atmosphere less time to cause ozone depletion. This year, though, the polar vortex that began in mid-February has continued and ozone depletion has been seen into the month of April. This is the biggest ozone depletion recorded since 2011 in the Northern Hemisphere. Researchers used satellite observations to measure ozone levels and found that on March 12, 2020 stratospheric ozone levels reached 205 Dobson Units.
The Importance of Ozone
The ozone layer is essential for protecting life on Earth from harmful UV radiation coming from the sun. Although this year’s ozone hole is larger than usual, there is currently no threat to human health because of it.
NASA satellites have recorded data about the ozone layer for many years, with specific focus on the 2019-2020 ozone layer over the Arctic. Changes in the ozone layer were detected most strongly when the polar vortex occured in February, and the ongoing effects of this event are still being recorded as of April 2020.
Gray, E. (2020, April 16). Unusual weather leads to ozone low over the Arctic. NASA Earth Observatory. https://earthobservatory.nasa.gov/images/146588/unusual-weather-leads-to-ozone-low-over-the-arctic
Gramling, C. (2020, April 7). The largest Arctic ozone hole ever measured is hovering over the North Pole. Science News. https://www.sciencenews.org/article/largest-arctic-ozone-hole-ever-measured-hovering-over-north-pole