Influences of Ozone Layer Depletion and Climate Change on UV-radiation: Impacts on Human Health and the Environment

Transcription

1 8th ORM, Geneve Environmental Effects Assessment Panel EEAP 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

2 Stratospheric chemistry, climate Depletion of stratospheric ozone (O 3 ) O 3 depleting substances UV-B radiation EEAP ODS applications, substitutes Human health Ecosystem health and services Materials Air Quality

3 EEAP The role of the Environmental Effects Assessment Panel Effects of ozone depletion Effects of climate change Consequences for life on Earth

4 EEAP KEY FOCUS AREAS (Full Assessment Report 2010) UV changes in relation to impacts: Human health Terrestrial ecosystems Aquatic ecosystems Carbon and other global chemical cycles Air quality Materials INTERACTIONS Ozone depletion, climate change, UV radiation

5 *UV-B radiation, nm Environmental Effects Assessment Panel Ozone depletion, climate change, UV radiation KEY OUTPUTS Assessment of future predictions of the effects of O 3, clouds & aerosols for: UV-B radiation causing sun-burn UV-B radiation involved in human vitamin D production Ecosystems, construction materials

6 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% At high latitudes (areas of large O 3 depletion): large increases in UV-B radiation Sufficient to cause sunburn

7 Ozone depletion, climate change, UV radiation Projected future changes in UV: ozone and clouds At high latitudes: cloud cover increases (by ca 5%) Reduction of UV radiation (UV already low) At low latitudes (near the equator): cloud cover decreases by ca 3% Increase in UV radiation (UV already high) Less easy to achieve exposure times needed to produce sufficient vitamin D Greater risk of sun-burn: additional increase in sunburning-uv of 3 to 6%

8 The Montreal Protocol has PREVENTED large increases in sun-burning UV Total chlorine (ppbv) O 3 (DU) Maximum UV Index UV Index: an estimation of the UV important for damage to human skin Reference future calculated using observed & currently predicted chlorine concentrations

9 Human health KEY OUTPUTS Assessment of the effects of UV radiation, and interactions with other environmental change, on human health, including: Immune responses Skin and eye diseases (especially cancers) Vitamin D production

10 M. Norval Non-melanoma Environmental Effects Assessment Panel Human health Exposure to sunburning UV-B radiation is a major environmental risk for skin cancers Cutaneous malignant melanoma Squamous cell carcinoma Basal cell carcinoma The Montreal Protocol has PREVENTED large increases in skin cancers that would have resulted from uncontrolled ozone depletion ALTHOUGH incidence currently is high

11 A. Cullen S. Ibbotson Human health Malignant melanoma of the eye Most common eye cancer in adults and may be a link between its incidence and UV-B radiation UV-induced allergy Occurs in ca 5-20% of the population often after first spring/summer exposure to UV radiation UV-induced immune-suppression Complex effect but increased UV exposure may have significant effects on infectious diseases and auto-immune diseases

12 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

13 Human health Solar UV-B at midhigh 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

14 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 10 o C 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

15 Terrestrial ecosystems KEY OUTPUTS Assessment of effects of ozone depletion since 1980 on current plant productivity Assessment of the effects of future changes in UV radiation, and interactions with other environmental change on: Food security & food quality Ecosystem responses to UV radiation & climate

16 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 Green pigment used for energy capture & growth + UV - UV

17 Terrestrial ecosystems Plant growth has been reduced by ca 6% in response to increased UV radiation in areas of significant ozone depletion - long-term effects of reduced plant growth may be important for potential carbon capture/retention - Interactions with other components of climate change

18 Terrestrial ecosystems Combined effects of predicted climate change & UV radiation: plants and ecosystems - 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 - Moderate drought: decreases UV sensitivity in plants - More frequent drought & rising temperatures reduce productivity Important implications for food security and quality Environmental Effects Assessment Panel

19 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 Reduces plant biomass production Promotes decay of dead plant material Effects on important ecosystem processes including nutrient cycling and CO 2 loss to the atmosphere

20 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

21 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

22 Aquatic ecosystems Ozone layer Clouds,aerosols UV attenuation Main factors affecting the quantity & quality of UV radiation received by aquatic organisms

23 Depth, m Aquatic ecosystems Quantity & quality of UV radiation received by aquatic organisms depends on: Water properties Ozone levels Clouds Elevation Irradiance, % of surface Dissolved organic matter determines UV penetration into water Penetration of UV- B, UV-A radiation & visible light in an alpine lake High UV irradiance Low levels of dissolved organic matter increased penetration

24 Aquatic ecosystems Dissolved organic matter is a key limiting factor for UV penetration in to water bodies 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

25 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 Increasing temperature increases breakdown of dissolved organic material Increasing CO 2 Increases acidity (low ph) Decreases skeletal formation in calcified organisms More exposure of aquatic organisms to solar UV-B Increased vulnerability to solar UV B radiation

26 Aquatic ecosystems Impacts of changes in temperature, CO 2 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

27 Carbon and other global chemical cycles Environmental Effects Assessment Panel 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

28 Carbon and other global chemical cycles Environmental Effects Assessment Panel Ecosystem responses to UV radiation and climate change will affect global chemical cycles, resulting in feedbacks into environmental change and its effects

29 Carbon and other global chemical cycles Environmental Effects Assessment Panel 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 CO 2 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

30 Carbon and other global chemical cycles Environmental Effects Assessment Panel Negative effects of climate change & UV radiation on aquatic organisms Increased run-off of organic matter from land into the oceans UV-induced breakdown of this organic matter Decreased CO 2 uptake by the oceans Increased CO 2 emissions from the oceans (also increased NOx ) Resulting increase in atmospheric CO 2 may enhance global warming beyond current predictions

31 Carbon and other global chemical cycles Environmental Effects Assessment Panel

32 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)

33 Tropospheric air quality UV initiates production of hydroxyl radicals ( OH), which are atmospheric cleaning agents, destroying many air pollutants, ODS, photochemical smog With O 3 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

34 Tropospheric air quality Surface (tropospheric) O 3 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 CO 2-50% increase in emissions of plant compounds (isoprene) - doubling of emissions of soil-derived NOx (from human activity, and from the ocean)

35 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

36 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

37 Effect of climatic variables on light-induced degradation of materials +, effectiveness Materials damage

38 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 Pine wood surface after 2 years of outdoor exposure

39 8th ORM, Geneve Environmental Effects Assessment Panel EEAP 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 Climate change Human health Materials