Influences of Ozone Layer Depletion and Climate Change on UV-radiation: Impacts on Human Health and the Environment Janet F. Bornman and Nigel D. Paul, co-chairs

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Influences of Ozone Layer Depletion and Climate
Change on UV-radiationImpacts on Human Health
and the EnvironmentJanet F. Bornman and Nigel
D. Paul, co-chairs
Environmental Effects Assessment Panel EEAP
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Depletion of strato-spheric ozone (O3)
Stratospheric chemistry, climate
UV-B radiation
O3 depleting substances
ODS applications, substitutes
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Environmental Effects Assessment Panel EEAP
The role of the Environmental Effects Assessment
Panel
Effects of ozone depletion
Effects of climate change
Consequences for life on Earth
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UV changes in relation to impactsHuman health
Terrestrial ecosystemsAquatic ecosystemsCarbon
and other global chemical cyclesAir
qualityMaterials
Environmental Effects Assessment Panel EEAP
KEY FOCUS AREAS (Full Assessment Report 2010)
INTERACTIONS Ozone depletion, climate change, UV
radiation
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Ozone depletion, climate change, UV radiation
KEY OUTPUTS
Assessment of future predictions of the effects
of O3, clouds aerosols for
UV-B radiation causing sun-burn
UV-B radiation involved in human vitamin D
production
Ecosystems, construction materials
UV-B radiation, 280-315 nm
Environmental Effects Assessment Panel
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Ozone depletion, climate change, UV radiation
Current UV-B radiation compared with 1980
Measurable effects of ozone depletion but also
large variability in UV-B radiation due to clouds
aerosols
Southern Hemisphere cloudier overall than
corresponding Northern Hemisphere (global
satellite data)
At mid-latitudes increases in UV-B radiation by
ca 5
Environmental Effects Assessment Panel
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Ozone depletion, climate change, UV radiation
Projected future changes in UV ozone and clouds
Environmental Effects Assessment Panel
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The Montreal Protocol has PREVENTED large
increases in sun-burning UV
1980 2020 2040 2065
Total chlorine (ppbv) 2 11.5 20 40
O3 (DU) 310 250 220 100
Maximum UV Index 10 12.5 15 30
UV Index an estimation of the UV important for
damage to human skin
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Human health
KEY OUTPUTS
Environmental Effects Assessment Panel
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Human health
Exposure to sunburning UV-B radiation is a major
environmental risk for skin cancers
The Montreal Protocol has PREVENTED large
increases in skin cancers that would have
resulted from uncontrolled ozone
depletion ALTHOUGH incidence currently is high
M. Norval
Environmental Effects Assessment Panel
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Human health
Environmental Effects Assessment Panel
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Human health
Need to balance the risks of over-exposure to UV
radiation with the potential beneficial effects
Importance of vitamin D
Vitamin D is produced in the skin following UV-B
irradiation
Supports bone health
May decrease risk of - several internal
cancers - autoimmune infectious diseases -
cardiovascular diseases
Effectiveness of oral vitamin D supplements, and
the health effects of very high vitamin D status
are both unclear
Environmental Effects Assessment Panel
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Human health
Solar UV-B at mid-high latitudes are below that
required for adequate Vitamin D synthesis from
Autumn-Spring
Balance between sun-burning UV-B radiation and
that needed for vitamin-D, and the effects of
future environment change remain unclear
Environmental Effects Assessment Panel
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Human health
Combined effects of climate change solar UV
radiation

• Higher temperatures may lead to more skin
  cancers
• For the same UV exposure, for every 10oC
  increase, there is an estimated 3-6 increase in
  skin cancers

• Several indications of further interactions
• Increase in certain infectious diseases (malaria,
  Lyme)
• Increase in allergic diseases
• Suppression of the immune response to disease
• Increased photosensitivity of the skin (temp.,
  dust -deserts)

Environmental Effects Assessment Panel
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Terrestrial ecosystems
KEY OUTPUTS
Assessment of effects of ozone depletion since
1980 on current plant productivity
Environmental Effects Assessment Panel
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Terrestrial ecosystems
Plant growth has been reduced by ca 6 in
response to increased UV radiation in areas of
significant ozone depletion
Growth reductions are due to direct damage plus
diversion of plant resources towards protection
and repair

• Loss of green pigment
• Reduced growth

UV
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Terrestrial ecosystems
Plant growth has been reduced by ca 6 in
response to increased UV radiation in areas of
significant ozone depletion
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Terrestrial ecosystems
Combined effects of predicted climate change UV
radiation plants and ecosystems

• Moderate drought decreases UV sensitivity in
  plants
• - More frequent drought rising temperatures
  reduce productivity

• Increasing temperature, rainfall leads to spread
  of plant pests
• - Increased UV-B radiation large effects on
  plant interactions with pests because of induced
  chemical compounds

Important implications for food security and
quality
Environmental Effects Assessment Panel
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Terrestrial ecosystems
Combined effects of predicted climate change UV
radiation plants and ecosystems
Climate-change-related reduced cloud cover (low
latitudes) Deforestation and other land-use
changes
Increased UV radiation exposure
Environmental Effects Assessment Panel
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Terrestrial ecosystems
Impacts of climate change land-use change on
organisms and ecosystems
Impacts of climate change changes in
stratospheric ozone on UV radiation (includes
increased UV-B radiation in some regions)
Implications for food security food
quality Ecosystem responses to UV radiation
climate
Environmental Effects Assessment Panel
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Aquatic ecosystems
KEY OUTPUTS
Assessment of the effects of future changes in UV
radiation, and interactions with other
environmental change on
Aquatic organisms and ecosystem processes
Sensitivity of waterborne human pathogens to UV
radiation
Environmental Effects Assessment Panel
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Aquatic ecosystems
Main factors affecting the quantity quality of
UV radiation received by aquatic organisms
Environmental Effects Assessment Panel
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Aquatic ecosystems
Dissolved organic matter determines UV
penetration into water

• Quantity quality of UV radiation received by
  aquatic organisms depends on
• Water properties
• Ozone levels
• Clouds
• Elevation

Penetration of UV-B, UV-A radiation visible
light in an alpine lake
High UV irradiance Low levels of dissolved
organic matter increased penetration
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Aquatic ecosystems

• Changes in climate and UV are expected to
• - Increase inputs of organic matter in some areas
  of the oceans
• Increase the degradation of dissolved organic
  matter
• The balance will vary between different oceanic
  regions, but in many areas, aquatic organisms
  will be exposed to increased UV radiation

Dissolved organic matter is a key limiting factor
for UV penetration in to water bodies
Environmental Effects Assessment Panel
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Aquatic ecosystems
Combined effects of predicted climate change UV
radiation global change processes
Environmental climate-driven changes may exceed
protective strategies to adapt to UV radiation
Environmental Effects Assessment Panel
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Aquatic ecosystems
Impacts of changes in temperature, CO2 and
acidity on aquatic organisms and ecosystems
Impacts of climate change changes in
stratospheric ozone on UV radiation penetrating
into water bodies
Implications for food security Ecosystem
response to UV radiation climate
Environmental Effects Assessment Panel
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Carbon and other global chemical cycles
KEY OUTPUTS
Assessment of the effects of future changes in UV
radiation and interactions with other
environmental change on
The cycling of carbon and other elements
The potential for feedbacks through changes in
global element cycles
Environmental Effects Assessment Panel
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Carbon and other global chemical cycles
Ecosystem responses to UV radiation and climate
change will affect global chemical cycles,
resulting in feedbacks into environmental change
and its effects
Environmental Effects Assessment Panel
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Carbon and other global chemical cycles
Interactions between continuing changes in UV
radiation and the effects of other components of
environmental change are diverse and
complex Interactions are best defined in the
oceans and involve - Decreased uptake of
atmospheric CO2 by the oceans - Increased
production and release of nitrous oxide from
the oceans
Ecosystem response to UV radiation and climate
change will affect global chemical cycles,
resulting in feedbacks into environmental change
and its effects
Environmental Effects Assessment Panel
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Carbon and other global chemical cycles
Resulting increase in atmospheric CO2 may
enhance global warming beyond current predictions
Environmental Effects Assessment Panel
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Carbon and other global chemical cycles
Environmental Effects Assessment Panel
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Tropospheric air quality
KEY OUTPUTS
Assessment of the interactive effects of ozone
depletion and other components of environmental
change on tropospheric ozone (at low
mid-latitudes), and other tropospheric air
pollutants
Assessment of effects on human health and
ecosystems of breakdown products of ODS
substitutes (HCFCs and HFCs)
Environmental Effects Assessment Panel
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Tropospheric air quality

• UV initiates production of hydroxyl radicals
  (OH), which are atmospheric cleaning agents,
  destroying many air pollutants, ODS,
  photochemical smog
• With O3 recovery, less UV, as a result OH is
  predicted to decrease globally by ca 20 by 2100

Potential for increased photochemical smog, with
negative effects on human health and the
environment
Environmental Effects Assessment Panel
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Tropospheric air quality
Surface (tropospheric) O3 in mid-latitudes is
predicted to increase because of climate change
and interactions with atmospheric chemistry
Drivers used in the models for this -
doubling of CO2 - 50 increase in emissions of
plant compounds (isoprene) - doubling of
emissions of soil-derived NOx (from human
activity, and from the ocean)
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Tropospheric air quality
CFC replacements break down into trifluoroacetic
acid (TFA) but this is currently judged to
present a negligible risk to human health or the
environment
Environmental Effects Assessment Panel
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Materials damage
KEY OUTPUTS
Assessment of effects of UV radiation and climate
change on construction materials
UV radiation degradation of plastics wood
Damage due to high temperatures, humidity,
atmospheric pollutants
Assessment of availability of technologies as
protective measures/agents
Environmental Effects Assessment Panel
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Materials damage
Effect of climatic variables on light-induced
degradation of materials , effectiveness
Environmental Effects Assessment Panel
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Materials damage
UV radiation and climate change shorten useful
outdoor lifetimes of materials

• Development of technologies to counteract these
  effects of UV radiation and climate change
• - allows service lifetimes of materials to be
  maintained or improved
• Use of plastic nanocomposites wood-plastic
  composites
• Increased use of nanomaterials as stabilisers

Environmental Effects Assessment Panel
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Environmental Effects Assessment Panel EEAP
Current future climate change interactions with
UV radiation add to the uncertainty of many
aspects of environmental impacts