Speaker
Dr
Rolf Müller
(Forschungeszentrum Jülich)
Description
This talk will describe the evolution of global ozone including ozone
in the polar regions. Conclusions will be largely based on the
WMO/UNEP Scientific Assessment of Ozone Depletion: 2014.
There are now several indications that the ozone layer is beginning to
recover from ODS-induced depletion. Nonetheless, the Antarctic ozone
hole will continue to occur at least until mid-century. Occasional
large Arctic ozone depletion, such as that in spring 2011 and 2016 is
also possible in coming decades. Recovery of polar ozone could be
delayed by increases in stratospheric aerosol that could be caused by
injection of sulphur by large volcanic eruptions or geoengineering.
Upper stratospheric ozone declined during the 1980s and early 1990s,
and has clearly increased by about 5% since 2000. The ozone decreases
until the mid-1990s were dominated by ODS increases. However, from
2000 to 2013 the decline in ODS abundances and the cooling by
increased carbon dioxide are both estimated to have made comparable
contributions to the observed upper stratospheric ozone increases.
In the mid-latitude lower stratosphere (15 to 25 km altitude), ozone
exhibited a long-term decline through the 1980s and early 1990s. Since
2000, ozone at these altitudes has remained approximately stable.
Tropical ozone is strongly dependent on transport, in particularly
tropical upwelling. Observations of changes in temperature and ozone
over the past three to five decades are suggestive of increased
upwelling of air in the tropical lower stratosphere. Therefore, in the
future, a decrease of tropical column ozone is conceivable.
Primary author
Dr
Rolf Müller
(Forschungeszentrum Jülich)
