A NASA-led study has documented an unprecedented depletion of Earth’s protective ozone layer above the Arctic last winter and spring caused by an unusually prolonged period of extremely low temperatures in the stratosphere.According to scientists the high atmosphere over the Arctic lost an unprecedented amount of its protective ozone earlier this year, so much that conditions echoed the infamous ozone hole that forms annually over the opposite side of the planet, the Antarctic.The stratospheric ozone layer, extending from about 10 to 20 miles (15 to 35 kilometers) above the surface, protects life on Earth from the sun’s harmful ultraviolet rays. The Antarctic ozone hole forms when extremely cold conditions, common in the winter Antarctic stratosphere.
The same ozone-loss processes occur each winter in the Arctic. To study the 2011 Arctic ozone loss, scientists from 19 institutions in nine countries (United States, Germany, The Netherlands, Canada, Russia, Finland, Denmark, Japan and Spain) analyzed a comprehensive set of measurements. So they found that at some altitudes, the cold period in the Arctic lasted more than 30 days longer in 2011 than in any previously studied Arctic winter, leading to the unprecedented ozone loss. Further studies are needed to determine what factors caused the cold period to last so long. Have to say that decreases in overhead ozone lead to increases in surface ultraviolet radiation, which are known to have adverse effects on humans and other life forms.