World of Change: Ozone Concentrations Over Antarctica
Based on Earth Observatory's World of Change series, this segment focuses on the formation and growth of the South Pole ozone hole and the slow stabilization of the ozone layer over the past several decades.
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Text, World of Change, Ozone Concentrations over Antarctica.
Title, Ozone Layer of the Stratosphere, South Pole, 1979 to 2018. Text, the ozone layer of the stratosphere protects life on Earth by absorbing ultraviolet light, which damages DNA in living things, including humans.
An image is credited to the International Space Station Expedition 28 crew. The view shows a thin layer of stratosphere over a thicker layer of troposphere.
Text, In the mid-1980s, satellite and ground-based monitoring began to show that ozone concentrations were plummeting over the South Pole each spring.
An image credited to N-O-A-A and NESDIS showing the ozone profile, a band within 40 kilometers of Earth's surface, thickest at the equator and thinnest over Antarctica. An inset shows Antarctica covered by a red splotch in 2015.
Text, The "hole" in the ozone layer was linked to the presence of chlorofluorocarbons (CFCs) and other pollutants, which destroy ozone molecules.
Text, the size of the ozone hole increased dramatically during the 1980s and early 1990s, but eventually stabilized as a result of the Montreal Protocol, an international treaty banning ozone-depleting chemicals.
A graph of the size of the ozone hole in area shows a growing trend from 1979, peaking from 2000 to 2005, then shrinking to 2018. A marker shows the Montreal Protocol.
Text, these maps, made using NASA satellite data, show the state of the ozone hole each year on the day the lowest ozone concentrations were measured. Year-to-year fluctuations in area, shape, and depth of the ozone hole are caused by variations in stratospheric temperature and circulation.
A globe focused on Antarctica features the outline of the continent with a legend showing the depiction of the ozone in Dobson units from 100 in dark red, to 200 in yellow, to 300 in white, to 400 in light blue, to 500 in dark blue.
in the year 1979, the image shows mostly light blue and dark blue bands over Antarctica, with a small yellow spot. As years pass, the blue areas shift slightly, but the yellow dot grows into an orange and dark red mass that shifts in shape and position but remains over the continent.
The spot becomes almost completely dark red in the 2000s. The fluctuations then become lighter, to orange and yellow by 2018.
Three panels show excerpts of this model of the ozone hole in 1979, 1994, and 2018.