Climate change threatens the Arctic: drastic ozone loss in sight!

Climate change threatens the Arctic: drastic ozone loss in sight!

The effects of climate change on the Arctic are alarming. In recent decades, temperatures in this sensitive area have risen about four times faster than the global average. This has serious consequences for the ozone layer and the regional climate. Experts from Goethe University and the Karlsruhe Institute of Technology (KIT) coordinate the research flights of the ASCCI (Arctic Springtime Chemistry-Climate Investigations) campaign to investigate the interactions between ozone, water vapor and climate change in the Arctic. The measurements focus on the spring months, which are characterized by the depletion of stratospheric ozone, especially at altitudes between 5 and 15 kilometers.

Professor Björn-Martin Sinnhuber and Professor Andreas Engel are leading the campaign. The current winter in the Arctic is characterized by noticeably cold conditions in the stratosphere, which can potentially lead to significant ozone depletion. Although the concentrations of ozone-depleting substances such as chlorofluorocarbons (CFCs) are decreasing, the degradation of these substances is a lengthy process that is not yet completely complete. Measurements document the presence of harmful chemicals that deplete ozone, and the research also leads to insights into the transport of air pollutants to the Arctic that act as short-lived greenhouse gases.

Ozone loss in the Arctic

Over the last two decades, ozone levels in the lower stratosphere have fallen sharply during late winter and spring. Chemical reactions with chlorine and bromine radicals are the main causes of this ozone loss. While ozone depletion in Antarctica proved to be extremely severe - ozone levels there in the 1990s were around 100 Dobson Units (DU) below the 1970-1982 average - the loss over the Arctic averages around 50 DU. Compared to the 100 DU higher initial values, the loss is significant, but there is no ozone hole in the Arctic and therefore no significant depletion of ozone at certain altitudes.

The differences in ozone destruction between Antarctica and the Arctic are mainly due to the different climatic conditions. While Antarctica is characterized by its near-circular shape and strong isolation, the irregular land-sea distribution and stronger atmospheric dynamics in the Arctic ensure more frequent exchange of warmer, ozone-rich air. This circumstance also leads to instability of the Arctic polar vortex and a rarer but more dramatic occurrence of polar stratospheric clouds (PSC).

Long-term forecasts and risks

Research shows that climate change and associated changes could further negatively impact ozone levels in the Arctic. An example of the drastic consequences is the record-breaking ozone loss that was documented during the “Mosaic” expedition in spring 2020. During this period, around 95% of the ozone at the ozone maximum was destroyed and the thickness of the ozone layer was reduced by more than half. Professor Markus Rex from the Alfred Wegener Institute (AWI) explains that climate change has directly contributed to this massive ozone loss. Projections show that this trend could continue until the end of the 21st century if global emissions continue unchecked.

The implications are significant, particularly for Europe, North America and Asia, where increased UV radiation could increase the risk of skin cancer and sunburns. Despite the fact that the 1987 Montreal Protocol helped reduce ozone-depleting substances such as CFCs, progress in combating ozone depletion remains critical. Halogenated gas, which contributes to global warming, simultaneously causes cooling in higher air layers of the stratosphere, producing paradoxical effects.

In the Arctic, the HALO research aircraft, stationed in Kiruna, Sweden, will be in operation until April to understand the influence of halogenated gas on the ozone layer. This joint initiative is supported by several institutions, including the Jülich Research Center and the German Aerospace Center (DLR). The findings from this research are essential to develop appropriate means to mitigate ozone depletion in the Arctic and to assess the long-term impact of human activities on the environment. CFC concentrations in the polar vortex have fallen to 90% of maximum since 2000, offering a slight glimmer of hope that the situation could improve in the long term if emissions are drastically reduced.