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SUMMARY:The ‘ozone hole’ – still a risk? Changes in stratospheric oz
 one and their implications for the troposphere (by Ulrike Langematz)
DTSTART:20190516T120000Z
DTEND:20190516T130000Z
DTSTAMP:20190510T094935Z
UID:presentation-94.series-5
DESCRIPTION:The stratospheric ozone layer protects life on Earth by absorb
 ing harmful ultraviolet radiation from the sun. 90% of the atmospheric ozo
 ne abundance reside in the stratosphere\; nevertheless\, changes in strato
 spheric ozone may directly impact the troposphere. \nWith increasing indus
 trial production of chlorine-containing halogens in the 1960/70s\, stratos
 pheric ozone began to decrease. First scientific studies found that haloge
 ns cause chemical ozone depletion in the stratosphere\, thus explaining th
 e strong decline in stratospheric ozone during the 1980s and 1990s\, when 
 the halogen concentrations grew rapidly. The most dramatic example is the 
 so-called Antarctic ozone hole\, a severe ozone decrease occurring over An
 tarctica each spring. In response\, regulations of the production and use 
 of the so-called ozone depleting substances (ODSs) were adopted by the Uni
 ted Nations in the Montreal Protocol of 1987. As a result of the Montreal 
 Protocol and further amendments and adjustments\, the ODS concentrations b
 egan to level off and slowly decline. Since the beginning of the century\,
  there is also evidence from measurements that stratospheric ozone has sta
 rted to increase. Models consistently project a full return of global mean
  stratospheric ozone to undisturbed\, historical values in the first half 
 of the 21st century. However\, because of complex dynamical and chemical i
 nteractions\, the date of ozone recovery in different atmospheric regions 
 will strongly depend on the future greenhouse gas scenario.\nHere\, an ove
 rview on the evolution of the ozone layer in the recent past is given and 
 new model projections of the future ozone from the upcoming “WMO/UNEP Sc
 ientific Assessment of Ozone Depletion” are presented. The role of clima
 te change for future ozone is discussed as well as the impacts of future o
 zone changes on the troposphere.
LOCATION:SR Wegener Center\, Brandhofgasse 5\, 1st floor
ORGANIZER;CN="Douglas Maraun";ROLE=CHAIR:MAILTO:douglas.maraun@uni-graz.at
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