Why has the ozone hole spread to the Arctic?

An international team of scientists has unravelled how the first ozone hole over the Arctic formed last spring. A comprehensive analysis of the unusually high ozone depletion in March/April 2011 has now been published in advance in the online issue of the journal Nature.

“The ozone hole over the Arctic was not only the result of a combination of past pollution due to air pollutants, its development is also connected with long-term changes in the climate system,” summarises Dr. Markus Rex, Potsdam atmospheric physicist.

At an altitude of 15 to 25 kilometres the trace gas ozone forms a natural barrier against harmful UV radiation from space. Under the influence of long-lived air pollutants that are first really activated by low temperatures the protective ozone layer can be extensively destroyed towards the end of the cold polar winter. At the same time the returning sun triggers a chain of complex chemical reactions that break down ozone.

“Last winter more Antarctic conditions prevailed in the stratosphere 20 kilometres above the Arctic than ever before since the beginning of observations in the mid-1960s,” said researchers.

Read more at Alfred Wegener Institute for Polar and Marine Research