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ENVIRONMENT
An update on the ozone hole
Amanda C. Maycock
University of Leeds
“Climate Changes over High Southern Latitudes”
RMetS National Meeting, Imperial College, 17 February 2016
The 2014 WMO/UNEP Ozone Assessment Report
Chapter 1: Update on OzoneDepleting Substances (ODSs) and
Other Gases of Interest to the
Montreal Protocol
Chapter 2: Update on Global
Ozone: Past, Present, and Future
Chapter 3: Update on Polar Ozone:
Past, Present, and Future
Chapter 4: Stratospheric Ozone
Changes and Climate
Chapter 5: Scenarios and
Information for Policymakers
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
The 2014 WMO/UNEP Ozone Assessment Report
Twenty Questions and Answers
About the Ozone Layer: 2014
Update
http://www.esrl.noaa.gov/csd/as
sessments/ozone/2014/twentyq
uestions2014update.pdf
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Outline
• Background



Ozone hole formation
Ozone hole by numbers
(short detour to the Arctic)
• How has ozone depletion affected Southern
hemisphere climate?



Large scale atmospheric circulation
Precipitation
Ocean and sea ice
• The future

Ozone recovery and increasing greenhouse gases
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone hole ingredients
Radiation
Ozo
ne
hole
Chemistry
Dynamics
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone hole ingredients
Strong and cold polar vortex
forms in stratosphere each winter
Polar vortex is stronger than in
northern hemisphere because of
reduced planetary wave
generation – main reason we do
not have an Arctic ozone hole
Provides an isolated
environment in which
polar stratospheric
clouds can form
ERA 40 Atlas
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone hole ingredients
50hPa temperature 5090°
Figure 3-1, WMO, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Chemistry and polar stratospheric clouds
Recent sightings of nacreous clouds
Cloud (and aerosol) particles enable
heterogeneous chemical reactions to take place
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone depleting substances in the atmosphere
WMO 20 questions, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone depleting substances in the atmosphere
Newly detected ozone depleting substances
WMO 20 questions, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Laube et al., 2014
Recent measurements of the ozone hole
Source: NASA
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Recent measurements of the ozone hole
Ozone hole area
(millions of km2)
Minimum total
column ozone
(Dobson units)
Source: NASA
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone depletion in the Arctic
Arctic total
column ozone
WMO, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone depletion in the Arctic
Arctic total
column ozone
WMO Bulletin, 2016
Chance of a similar event this year?
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
A hint of ozone recovery?
Timeseries of
“dynamical” component
of interannual polar
column ozone anomaly
Timeseries of polar total
column ozone anomaly
with “dynamical”
component removed
Salby et al., 2011
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
A hint of ozone recovery?
Timeseries of
“dynamical” component
of interannual polar
column ozone anomaly
Timeseries of polar total
column ozone anomaly
with “dynamical”
component removed
Salby et al., 2011
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Lower stratospheric temperature trends (C/decade) 1979-2012
MSU satellite observations
CMIP5 climate models
Figure 4-3, WMO, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Lower stratospheric temperature trends (C/decade) 1979-2012
MSU satellite observations
CMIP5 climate models
Figure 4-3, WMO, 2014
•
•
Enhanced cooling trend over southern polar cap in spring
Captured by models that include ozone depletion
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Pressure-time cross sections of polar climate trends
Temperature
Geopotential height
Thompson and Solomon, 2002
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Pressure-time cross sections of polar climate trends
Temperature
Geopotential height
Thompson and Solomon, 2002
•
Seasonality of the ozone hole means its tropospheric climate
impacts are limited to austral summer
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Latitude-pressure cross section of zonal mean zonal
wind Dec-Feb trend 1960-2000
Trend projects
onto Southern
Annular Mode
(SAM)
Previdi and
Polvani, 2014
Contours show climatology, shading shows trend
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected midlatitude weather?
Zonal wind trend
Jet latitude
Ndara et al., 2013
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected midlatitude weather?
Zonal wind trend
Rossby wave breaking
Jet latitude
Cut-off lows
Ndara et al., 2013
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Trend
Congruent with SAM
500hPa
geopotential
height
Surface air
temperature
/wind
Thompson and
Solomon, 2002
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Trend
Congruent with SAM
500hPa
geopotential
height
Surface air
temperature
/wind
Thompson and
Solomon, 2002
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
The relative roles of ozone and greenhouse gases
2000-1960 sea level pressure changes in a model with prescribed forcings
Ozone depletion
Greenhouse gases
Ozone + GHGs
(Ozone + GHGs) - ozone
Ozone explains majority of observed large-scale circulation trends
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Polvani et al, 2011
How has ozone depletion affected climate?
GPCP observed precipitation trends
Kang et al, 2011
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
GPCP observed precipitation trends
GPCP observed precipitation trends
Model precip trend forced by ozone
Kang et al, 2011
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected the oceans?
Impacts of surface wind stress changes on southern ocean circulation
Waugh et al, 2011
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected the oceans?
Impacts of surface wind stress changes on southern ocean circulation
Waugh et al, 2011
•
•
Increased age in circumpolar deep water and decreased age in
subtropical subantarctic mode water
Suggests changes in ventilation of the southern ocean in recent years
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Has ozone depletion affected Antarctic sea ice?
1978
1990
2002
2014
Sigmond and Fyfe, 2014
•
New results suggest recent Southern hemisphere sea ice changes
cannot be explained by effects of ozone hole
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
How has ozone depletion affected climate?
Figure 4-22, WMO, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
The World Avoided by the Montreal Protocol
Newman et al, 2009
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
The World Avoided by the Montreal Protocol
Newman et al, 2009
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
The World Avoided by the Montreal Protocol
Newman et al, 2009
Climate benefits of the
Montreal Protocol: the
greatest success for
reducing anthropogenic
climate change to date
Velders et al, 2007
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Factors that will affect stratospheric ozone in the future
WMO, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone recovery and future southern hemisphere climate
Total column ozone over southern pole in October
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone recovery and future southern hemisphere climate
Modelled future trends in southern hemisphere jet position
for high greenhouse gas emissions scenario
Austral summer
Austral winter
Barnes et al, 2014
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Ozone recovery and future southern hemisphere climate
Modelled future trends in southern hemisphere jet position
for high greenhouse gas emissions scenario
Austral summer
Austral winter
Barnes et al, 2014
•
•
In summer, ozone recovery opposes greenhouse gas effects
over first half of century
Greenhouse gas effect dominates post-recovery, and in winter
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016
Thank you for your attention
Any questions?
[email protected]
“Climate changes over high southern latitudes”, RMetS meeting, 17 February 2016