The ozone layer over Norway and the Arctic

The ozone layer over Norway and the Arctic During the winter of 2011, NILU observed a record amount of depletion in the ozone layer over the Arctic, which has led to a discussion in the research community as to whether an ozone hole has opened over the Arctic for the first time ever. A preliminary analysis of NILU’s measurements from Svalbard shows that there was about a 40 % loss of ozone over the area during the winter.

The reason for these record low ozone values remains unclear, but for a number of years, some researchers have pointed to a connection between climate change and increased ozone breakdown over the Arctic during the spring. An increase in greenhouse gases in the atmosphere increases temperatures in the lower layers of the atmosphere, but results in colder temperatures in the stratosphere, where the ozone layer is found. In the spring, when the sun returns to the Arctic and it is still very cold in the upper layers of the atmosphere, the combination of chlorine and bromine compounds in the stratosphere creates conditions that result in a substantial amount of chemical ozone loss. While cold winters in the Arctic stratosphere were rare in the past, we now see this happening more frequently, and the winters are becoming ever colder.

The relationship between climate change and ozone is extremely complex, and there many reasons other than climate change that would explain ozone losses. Effects such as changes in atmospheric transport patterns and natural variations, such as solar activity, may also prove to play an important role. It is therefore essential to continue a strong monitoring programme in northern areas. This important research topic deserves an increased focus.

The monitoring of ozone and UV represents a part of NILU’s overall national monitoring responsibilities conducted by the institute on behalf the Norwegian Environment Agency.