This year the ozone hole over Antarctica is noticeably small. Scientists at the German Aerospace Center (DLR) have determined that it is the second-smallest ozone hole since the end of the 1980s – since the 1987 Montreal Protocol and its follow-up agreements on protecting the ozone layer. Current measurements show a maximal extent of the ozone hole of some 20 million square kilometres this year. By comparison: the record low value of September 2000 is just under 30 million square kilometres. Recovery is also revealed by the thickness of the ozone layer – the lowest current values for the layer’s thickness are higher than those of the last 30 years.
"Monitoring and analysing ozone values and other demanding climate research activities have been important topics for decades at the Institute of Atmospheric Physics and the Earth Observation Center as well as at many other DLR research units. With our measurements, analyses and models we are bringing together at DLR a broad foundation of data that can be useful when seeking approaches and courses of action relating to climate change and the ozone layer– which is anchored in the new Strategy 2030 ", relates Prof. Markus Rapp, Director of DLR’s Institute of Atmospheric Physics.
Since the ozone hole has its greatest extent in Antarctic springtime, measurements collected in September and October are particularly meaningful. For the current assessments, the DLR specialists consulted the latest measurement data from the European satellite instrument GOME-2. "Since we now have many years’ worth of information gathered from satellites, it is possible to immediately detect changes and analyse them scientifically. Our work is closely integrated in international activities", explains Dr.-Ing. Diego Loyola of DLR’s Remote Sensing Technology Institute.
There are two main reasons for the positive development evident in this year’s reduced chemical breakdown of the ozone layer in the Antarctic. The first reason is the warming of the Antarctic stratosphere in September 2017. Temperatures vary due to natural fluctuations in stratospheric dynamics from year to year, and in warmer years stratospheric ozone breaks down to a much smaller extent.
The second reason for this year’s smaller ozone hole is that fact that the current concentrations of chlorine in the stratosphere – including chlorofluorocarbon (CFC) –are much lower than they were at the end of the last century, so not as much ozone can be destroyed. Current measurements show some 15 percent lower chlorine concentrations than in 2000. This demonstrates the great success of the Montreal and London Protocols, which regulate the production and use of ozone-destroying substances. The environmental accords of 1987 and 1990 were signed by all member states of the United Nations and are binding under international law.
"If the Montreal Protocol and the follow-up agreements continue to be strictly followed, we can assume that the ozone layer will recover and that the ozone hole will close up again in the next decades", states Prof. Dr Martin Dameris of DLR’s Institute of Atmospheric Physics.
Farewell, ozone hole?
Recovery of the ozone layer will continue over the next few years. By 2060 at the latest the ozone hole will be a thing of the past – that is shown by the results of simulations carried out with numeric climate chemistry models, also at DLR, and published in the reports of the World Meteorological Organization (WMO).
Global monitoring of the ozone layer continues with the launch of the European earth observation satellite Sentinel-5P on 13 October 2017. On board that satellite the "TROPOMI" spectrometer (TROPOspheric Monitoring Instrument) will measure at high spatial resolution climate-relevant trace gases in the atmosphere like ozone (O3) and air pollutants like nitrogen oxide (NO2) and sulphur oxides (SO2). These data can be used for even more precise measurement of air pollution and forecasts based on climate models. The German Remote Sensing Data Center at DLR in Oberpfaffenhofen established the ground segment and is responsible for systems operation. TROPOMI data are analysed at DLR’s Remote Sensing Technology Institute and processed for use in future climate research.