The Ozone Hole and Southern Hemisphere Climate Change · The Ozone Hole and climate change NASA...
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The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology The Ozone Hole and Southern Hemisphere Climate Change Julie Arblaster Climate Change Science Team, Bureau of Meteorology Climate Change Prediction group, NCAR www.cawcr.gov.au
Transcript of The Ozone Hole and Southern Hemisphere Climate Change · The Ozone Hole and climate change NASA...
The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology
The Ozone Hole
and Southern Hemisphere Climate Change
Julie Arblaster Climate Change Science Team, Bureau of Meteorology
Climate Change Prediction group, NCAR
www.cawcr.gov.au
The Ozone Hole and climate change
NASA
Ozone depletion over
Antarctica of more than 50%
compared to 1980 levels
Predominantly in spring
months, impact on surface
climate in summer
Recovery of the ozone
hole projected by mid-late
21st Century
Stratospheric ozone has
only a minor impact on
global surface temperatures
Ozone depletion and Southern Hemisphere
atmospheric circulation
Son et al 2010
Depletion =>
cooling in
Antarctic
stratosphere =>
changes in
atmospheric
circulation and
rainfall
DRY WET
recent research suggests jet has moved poleward by ~2 latitude since 1979
Ozone depletion and Southern Hemisphere
atmospheric circulation
Southern Annular Mode (SAM) index measures strength & position of winds
SA
M index
=> Ozone impacts SAM & surface climate predominantly in summer
=> Recent trend in the SAM due primarily to ozone depletion
Thompson et al. Nature Geosciences, 2011
Impacts on surface climate
Impacts of increasing summertime SAM (~ozone depletion)
implications for Antarctic sea-ice, ice sheets and
carbon uptake by the Southern Ocean
Thompson et al. Nature Geosciences, 2011
surface temperature & wind sea surface temperature & wind
Impacts on summer surface climate
Impacts of increasing
summertime Southern
Annular Mode
(~ozone depletion)
Warm over New
Zealand, dry in west,
wet in east
Wet and cool over
southern Australia
Thompson et al. Nature Geosciences, 2011
temperature rainfall
rainfall
Kang et al., Science, 2011
Recent studies show these
impacts can be captured by
climate models
Climate model experiments
observed summer
rainfall change from
1979-2000
climate model summer
rainfall change driven by
ozone depletion
What of the future?
Son et al 2010
<= past
future =>
Future changes in the Southern Hemisphere
GHGs
Son et al 2010
Ozone depletion and atmospheric circulation
Thompson et al. Nature Geosciences, 2011
SA
M index
SA
M index
Ozone depletion
and greenhouse
gases act together to
drive past changes
Ozone recovery
and greenhouse
gases drive opposite
changes
Southern Annular Mode (SAM) index measures strength & position of winds
Meehl et al, J Climate, 2012 and Cionni et al 2011
New opportunities to assess the
role of ozone versus greenhouse
gases on the SH circulation in
lead up to IPCC 5th Assessment
Report:
– all models include ozone
recovery into the future – a number of chemistry-climate
models participating – a number of high-top models
participating
Stratospheric ozone depletion
and recovery included in all
participating models
Climate modelling intercomparison project
Future climate change scenarios
a poleward shift in the SH
extratropical circulation
(westerly jet, SAM) is one of
the most robust responses
to global warming
ozone recovery will offset
this shift in austral summer
to some extent
which forcing dominates in
future climate change
scenarios?
=> low-emissions scenario RCP2.6: ozone recovery wins and SH winds shift
equatorward
=> high-emissions scenario RCP8.5: GHGs wins and SH winds poleward
Meehl et al. J Climate 2012
south pole equator
heig
ht
tropopause
Many recent papers on understanding impacts of stratospheric ozone
in recent and future trends
- ties to changes in Tropics eg. Hadley Cell and subtropics
- much work on proposed mechanisms
- potential impacts on extremes
Conclusions
The ozone hole has driven
much of the observed shift in
Southern Hemisphere mid-
latitude winds during summer
with broad impacts on surface
climate
Ozone recovery will offset the
response to climate change to
some extent
?
The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology
Julie Arblaster
Climate Change Science Team, CAWCR
Climate Change Prediction group, NCAR
Email: [email protected]
Thank you www.cawcr.gov.au
