Transcript Environmental Effects Assessment Panel, EEAP Environmental

Environmental Effects Assessment Panel
22nd MOP
EEAP
Bangkok
Stratospheric
chemistry, climate
SAP
Depletion of stratospheric ozone (O3)
UV-B radiation
O3 depleting substances
EEAP
TEAP
Air
ODS applications, costeffective options
Ecosystem
health and
services
Quality
Human
health
Materials
Environmental Effects Assessment Panel
22nd MOP
EEAP
Bangkok
KEY FOCUS AREAS FROM
THE FULL ASSESSMENT REPORT 2010
Interactions with climate change
Ozone depletion, climate change, UV radiation
KEY FINDINGS
Strong interactions between O3 depletion
& climate change
Future predictions for sun-burning UV-B
radiation - effects of O3, clouds & aerosols
Consequences for human Vitamin D
production
World avoided – implications for effects
(UV-B radiation, 280-315 nm)
Environmental Effects Assessment Panel
Ozone depletion, climate change, UV radiation
Currently
• UV-B radiation: Large variability due to clouds & aerosols
• Mid-latitudes: increased UV-B irradiances: ca 5% relative
to 1980
• Large increases in UV-B radiation in areas of large O3
depletion
sufficient to induce sunburn
• S Hemisphere: cloudier overall than corresponding NH
(global satellite data)
Ozone depletion, climate change, UV radiation
Projected changes in ozone and clouds
• Cloud cover increases at
high latitudes (by ca 5%)
Reduction of UV radiation
(UV already low)
More difficult to achieve
optimal exposure times for
sufficient vitamin D
production
• Cloud cover decreases at
low latitudes by ca 3%
(near the equator)
Increase in UV radiation
(UV already high)
Additional increase in
sunburning-UV of 3 to 6%
The Montreal Protocol has PREVENTED
large increases in sun-burning UV radiation (UV index)
Total chlorine (ppbv)
1980
2
2020
11.5
2040
20
2065
40
O3 (DU)
UV Indexmax
310
10
250
12.5
220
15
100
30
UV Index: an estimation of the UV levels important for the
effects on the human skin calculated using
observed &
currently
predicted chlorine
concentrations
Human health
KEY FINDINGS
Impacts of UV-B radiation on:
Increasing cataract & skin cancer incidence
Decreased immunity
Interactions with climate change
Vitamin D production
Environmental Effects Assessment Panel
Human health
Need for balancing potential beneficial effects of UV with
over-exposure: Importance of vitamin D
• 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 supplementation?
• High vitamin D status beneficial?
Environmental Effects Assessment Panel
Human health
Exposure to sunburning UV-B radiation
Major environmental risk for skin cancers
Cutaneous malignant melanoma
Squamous cell carcinoma
Nonmelanoma
Basal cell carcinoma
M. Norval
Environmental Effects Assessment Panel
Human health
Malignant melanoma
of the eye
• Most common eye cancer
in adults
• May be a link between
UV-B radiation & incidence
A. Cullen
UV-induced allergy
• Occurs in ca 5-20% of the
population
• Often after first
spring/summer exposure
S. Ibbotson
World avoided:
Human health protected
• By 2065: Peak values
of sun-burning UV
radiation could have
tripled at midnorthern latitudes
• With the MP, clear-sky
UV radiation
_only
Sun-burning UV radiation with and
without the Montreal Protocol
slightly greater
than that prior to the
start of O3 depletion
P. Newman, R. McKenzie
Human health
Combinations of climate change & solar UV radiation
• Higher temperatures likely lead to more skin cancers
• For the same UV irradiance: for every 10C increase,
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)
Terrestrial ecosystems
KEY FINDINGS
Decreased plant productivity in areas of large
ozone depletion
Climate change & land-use change:
Regional increased UV-B radiation
UV radiation and climate change:
- Implications for food security & quality
- Evolving ecosystem modifications &
acclimation to UV radiation & climate
Environmental Effects Assessment Panel
Terrestrial ecosystems
Plant productivity & adaptation/repair
•
Plant growth is reduced in response to increased UV
ca 6% reduction in plant growth since 1980 in areas of
significant ozone depletion
•
Caused by:
- direct damage
- increased diversion of plant resources towards
protection and repair processes
•
Consequences:
- long-term effects of reduced plant growth may be
important for potential carbon capture/retention
UV-B radiation causes damage in Antarctic plants
• Green
• Loss of green
pigment used
for energy
capture &
growth
pigment
• Reduced
growth
Pigment loss
+ UV
- UV
High pigment
levels
Microscopic
views
Turnbull et al. 2005
Many plants produce screening pigments that
protect against UV damage (induced antioxidants)
Mosses
Lettuce
+ UV
+ UV
- UV
+ UV
S. Robinson
N. Paul
Terrestrial ecosystems
Combinations of predicted climate change & UV radiation
Effects on plant and ecosystem response
Example 1
•Spread of plant pests with increasing temperature, rainfall
+ >>> UV-B radiation: large effects on plant interactions
with pests
Induces increases in certain compounds
usually decreases plant consumption by e.g. insects
Important implications for food security and quality
Terrestrial ecosystems
Combinations of predicted climate change & UV radiation
Effects on plant and ecosystem response
Example 2
• Moderate drought: decreases UV sensitivity in plants
•
But further decreases in rain + increasing temperatures:
Reduced plant growth and survival
Environmental Effects Assessment Panel
Terrestrial ecosystems
UV radiation and global environmental change
Example 3
Predicted reduced cloud cover (low latitudes)
Deforestation
Land-use changes
Promotes decay of dead plant material
Increased UV
radiation
exposure
important ecosystem process for
nutrient cycling
also CO2 loss to the atmosphere
Aquatic ecosystems
KEY FINDINGS
Increased exposure to UV radiation with climate
change
Potentially greater vulnerability to UV radiation
Changes in UV transparency of waters
-Increased in some regions
-Decreased in others
Consequences for sensitivity of waterborne
human pathogens to UV radiation
Environmental Effects Assessment Panel
Main factors affecting the quantity & quality of
UV radiation received by aquatic organisms
Ozone layer
Clouds,aerosols
UV attenuation
Environmental Effects Assessment Panel
Penetration of UV-B, UV-A radiation and visible light
in an alpine lake
•
High UV irradiance
•
Low levels of dissolved organic matter
>>>
penetration
Irradiance as % of surface
1
10
100
Depth, m
0
5
10
15
20
Environmental Effects Assessment Panel
Aquatic ecosystems
Climate change and solar UV radiation
Environmental climate‐driven changes may exceed
protective strategies to adapt to UV radiation
Increasing temperature
increases breakdown of
dissolved organic material
More UV exposure to
aquatic organisms
Increasing CO2
Increases acidity (low pH)
Decreases skeletal
formation in calcified
organisms
more vulnerable to solar
UV‐B radiation
Biogeochemical cycles
KEY FINDINGS
UV radiation & climate change interactions
accelerate global carbon cycling
Effect of decreased uptake of atmospheric CO2 by
oceans on living organisms
Causes & consequences of increased production
and release of nitrous oxide
Environmental Effects Assessment Panel
Carbon cycling
in terrestrial and aquatic
ecosystems
Solar UV
radiation
Feedbacks
Biogeochemistry
of trace gases
and aerosols
Central to UV
and climate
change
Climate
change
Biogeochemical cycles
Predicted increase in atmospheric CO2 may enhance
global warming beyond current predictions
•
Projected warmer and drier conditions increases
UV-induced breakdown of dead plant material
•
Negative effects of climate change & UV radiation on
aquatic organisms decrease uptake of atmospheric CO2
by the oceans
•
Climate-related increases in run-off of organic material
from land to oceans and UV-induced breakdown of this
material increase emission of CO2 from the oceans
Biogeochemical cycles
Climate-related increase in run-off also increases nitrogen
input in to the oceans; further N inputs from atmosphere
Increasing production of nitrous oxide, (N2O)
Increases O3-depletion
Increases UV radiation
Increases the GH effect
Tropospheric air quality
KEY FINDINGS
Projected increase in tropospheric ozone
(low & mid-latitudes)
Implications of changes in climate, pollutants &
stratospheric O3 on human health & the environment
Likely insignificant effect of breakdown products of
ODS substitutes
-hydrochlorofluorocarbons (HCFCs)
-hydrofluorocarbons (HFCs)
Environmental Effects Assessment Panel
Tropospheric air quality
Future changes in UV radiation & climate will modify
air quality
•
UV initiates production of
hydroxyl radicals (∙OH)
•
A controlling factor of
photochemical smog
•
With O3 recovery, less UV
Consequences
•
•
• ∙OH is an atmospheric
‘cleaning agent,’ destroys
many air pollutants, ODS,
GHGs
• ∙OH is predicted to
decrease globally by ca
20% by 2100
Potential for increased photochemical smog
Negative effects on human health, environment
Tropospheric air quality
Predicted changes in surface ozone between 2000 & 2050
because of climate change and interactions with
atmospheric chemistry
• Further increase in tropospheric O3 in mid-latitudes
(ca 4 ppbv)
• 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)
Breakdown of CFC replacements into
trifluoroacetic acid (TFA)
HFCs, HFOs,
and HCFCs
CF3- CXyH
chlorodifluoroacetic
O
Salt lakes with
no outflow, loss
by evaporation
only – negligible
effects from TFA
O
CF2Cl-C-OH
CF3-C-OH
TFA
Breakdown in
soil and water
Small fraction of
TFA from natural
sources –
negligible effect
TFA: currently judged to present a negligible risk to
human health or the environment
Materials damage
KEY FINDINGS
Implications of climate change for
construction materials
UV radiation degrades plastics & wood
Increased damage with high temperatures,
humidity, & atmospheric pollutants
Current availability of photostabilisers as
protective measures/agents
Environmental Effects Assessment Panel
Effect of climatic variables on light-induced
degradation of materials
+, effectiveness
Polymer
Wood
Increase
in Solar
UV
Increase
in Temp.
Increase
in
Humidity
Increase
in
Pollutants
S, NOx, O3
++++
+++
+
+
+++
++
+++
+
Materials damage
UV radiation and climate change shorten useful
outdoor lifetimes of materials
Improved stabilisation technologies
• Allow service lifetimes of materials to be maintained
or improved
• Some control of deleterious environmental effects
Stabilisers
• Relatively high solar UV radiation stability
• Plastic nanocomposites and wood-plastic composites
• Nanofillers in composites
Environmental Effects Assessment Panel
UV radiation discoloration effects on polymer pigments
• UV-caused chalking from
titanium dioxide in rigid PVC
• Degraded surfaces release
titanium dioxide bound in the
PVC matrix
• UV-caused chalking of vinyl
siding & rundown with rain
Titanium dioxide (TiO2)photostabiliser for plastics
http://www.olympic.com/paint/Learn_How/exterior_problems.aspx
Materials damage
Use of composites to lessen UV degradation of materials
Pine wood surface after 2
years of outdoor exposure
Products made with
wood-plastic composites
Adapted from Fabiyi et al. 2008 & Taylor et al., 2009
LINKAGES: Environmental effects of O3 depletion & its
interactions with climate change
Terrestrial and aquatic
ecosystems
Solar UV
radiation
Current & future climate
change interactions with
UV radiation add to the
uncertainty of many
aspects of environmental
impacts
Human health
Materials
Climate
change