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Less ozone over the tropics

NASA Ozone Watch The ozone layer over Antarctica (the blue area inside the dotted circle) has increased by 20% since 2005NASA Ozone Watch

Using satellite data, researchers at NASA have identified a 20% recovery in the ozone layer over Antarctica in 2016 compared to 2005. The change is attributed to the 1987 Montreal Protocol, which banned the production of chlorofluorocarbons (CFCs), compounds that inhibit the formation of ozone in the upper atmosphere (Geophysical Research Letters, January 4). Despite this progress, the ozone layer is not recovering at lower latitudes between 60 degrees North, which runs through central Canada, and 60 degrees South, which runs between South America and Antarctica, according to another study by researchers from Europe, the US, and Canada (Atmospheric Chemistry and Physics, February 6). “The potential for harm in lower latitudes may actually be worse than at the poles, because ultraviolet radiation is more intense in these regions and more people live there,” Joanna Haigh, a researcher at Imperial College London and coauthor of the paper, said in a statement. There is still no explanation for the depletion of the ozone layer at lower latitudes. One possibility is that a changing pattern of atmospheric circulation is carrying ozone away from the lower layers of the atmosphere between the tropics and mid-latitude regions. The ozone layer filters ultraviolet radiation from the sun and protects plants, animals, and humans from DNA damage.