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Climate Change and Ozone Loss Key Concepts Changes in Earth’s climate over time Factors affecting climate Possible effects of global warming Adapting to climate change Human impacts on the ozone layer Protecting and restoring the ozone layer Past Climate Changes Past global temperatures Recent trends in global temperatures Temperature change over past 22,000 years 2 Temperature change (°C) Agriculture established 1 0 -1 -2 End of last ice age -3 Average temperature over past 10,000 years = 15°C (59°F) -4 -5 20,000 10,000 2,000 1,000 Years ago 200 100 Now Temperature change over past 1,000 years Temperature change (°C) 1.0 0.5 0.0 -0.5 -1.0 1000 1100 1200 1300 1400 1500 1600 1700 Year 1800 1900 2000 2101 Average surface temperature (°C) Average temperature over past 130 years 15.0 14.8 14.6 14.4 14.2 14.0 13.8 13.6 1860 1880 1900 1920 1940 Year 1960 1980 2000 2020 The Greenhouse Effect Greenhouse effect Greenhouse gases Table 21-1 Major Greenhouse Gases from Human Activities Average Time in the Troposphere Relative Warming Potential (compared to CO2) Greenhouse Gas Human Sources Carbon dioxide (CO2) Fossil fuel burning, especially coal (70– 75%), deforestation, and plant burning 100–120 years 1 Methane (CH4) Rice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelines 12–18 years 23 Nitrous oxide (N2O) Fossil fuel burning, fertilizers, livestock wastes, and nylon production 114–120 years 296 Chlorofluorocarbons (CFCs)* Air conditioners, refrigerators, plastic foams 11–20 years (65–110 years in stratosphere) 900–8,300 HydrochloroAir conditioners, refrigerators, plastic foams fluorocarbons (HCFCs) 9–390 470–2,000 Hydrofluorocarbons (HFCs) Air conditioners, refrigerators, plastic foams 15–390 130–12,700 Halons Fire extinguishers 65 5,500 Carbon tetrachloride Cleaning solvent 42 1,400 360 340 320 300 280 Carbon dioxide 260 240 220 +2.5 200 0 180 –2.5 –5.0 Temperature change End of last ice age 160 120 80 40 0 Thousands of years before present –7.5 –10.0 Variation of temperature (˚C) from current level Concentration of carbon dioxide in the atmosphere (ppm) 380 Parts per million 410 360 310 260 1800 1900 2000 Year Carbon dioxide (CO2) 2100 Parts per million 2.4 1.8 1.2 0.6 1800 1900 2000 Year Methane (CH4) 2100 320 Parts per million 310 300 290 260 1800 1900 2000 Year Nitrous oxide (N2O) 2100 Climate Change and Human Activities Increased use of fossil fuels Deforestation Global warming Melting icecaps and glaciers Rising sea level Table 21-2 Major Characteristics of Global Warming and Ozone Depletion Characteristic Global Warming Ozone Depletion Region of atmosphere involved Troposphere. Stratosphere. Major substances involved CO2, CH4, N2O (greenhouse gases). O3, O2, chlorofluorocarbons (CFCs). Interaction with radiation Molecules of greenhouse gases absorb infrared (IR) radiation from the earth’s surface, vibrate, and release longer-wavelength IR radiation (heat) into the lower troposphere. This natural greenhouse effect helps warm the lower troposphere. About 95% of incoming ultraviolet (UV) radiation from the sun is absorbed by O3 molecules in the stratosphere and does not reach the earth’s surface. Nature of problem There is a high (90–99%) probability that increasing concentrations of greenhouse gases in the troposphere from burning fossil fuels,deforestation, and agriculture are enhancing the natural greenhouse effect and raising the earth’s average surface temperature (Figure 21-2, bottom right, and Figure 21-11, p. 471). CFCs and other ozone-depleting chemicals released into the troposphere by human activities have made their way to the stratosphere, where they decrease O3 concentration. This can allow more harmful UV radiation to reach the earth’s surface. Possible consequences Changes in climate, agricultural productivity, water supplies, and sea level. Increased incidence of skin cancer, eye cataracts, and immune system suppression and damage to crops and phytoplankton. Possible responses Decrease fossil fuel use and deforestation; prepare for climate change. Eliminate or find acceptable substitutes for CFCs and other ozone-depleting chemicals. Greenland Clouds 50–55% Snow 80–90% City 10–15% Forest 5% Grass 15–25% Bare sand 30–60% Oceans 5% Height above or below present sea level (meters) 0 250,000 0 –130 –426 200,000 150,000 100,000 Years before present 50,000 0 Present Height above or below present sea level (feet) Today’s sea level Projecting Future Changes in Earth’s Climate Climate models Apparent influence of human activities Could be natural changes Troposphere Warming from decrease Aerosols Cooling from increase CO2 removal by plants and soil organisms CO2 emissions from land cleaning, fires, and decay Heat and CO2 removal Heat and CO2 emissions Greenhouse gases Ice and snow cover Shallow ocean Land and soil biota Natural and human emissions Long-term storage Deep ocean Cell Clouds Land Ocean 6.0 5.5 5.0 Change in temperature (ºC) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100 Year Factors Affecting the Earth’s Temperature Changes in solar output Changes in Earth’s albedo Moderating effect of oceans Clouds and water vapor Air pollution Greenland Antarctica Some Possible Effects of a Warmer World Possible Benefits from a Warmer Atmosphere Less severe winters More precipitation in some dry areas Less precipitation in some wet areas Increased food production in some areas Expanded population and ranges of some species Present range Future range Overlap 100 Mean Sea-Level Rises (centimeters) 90 80 70 High Projection Shanghai, New Orleans, and other low-lying cities largely underwater 60 50 40 30 Medium Projection More than a third of U.S. wetlands underwater 20 10 Low Projection 0 2010 2020 2030 2040 2050 Year 2060 2070 2080 2090 2100 Oil rig Coal power plant Tanker delivers CO2 from plant to rig Tree plantation CO2 is pumped down from rig for deep ocean disposal Abandoned oil field Switchgrass Crop field CO2 is pumped down to reservoir through abandoned oil field Spent oil reservoir is used for CO2 deposit = CO2 deposit = CO2 pumping What Can You Do? Reducing CO2 Emissions • Drive a fuel-efficient car, walk, bike, carpool, and use mass transit • Use energy-efficient windows • Use energy-efficient appliances and lights • Heavily insulate your house and seal all drafts • Reduce garbage by recycling and reuse • Insulate hot water heater • Use compact fluorescent bulbs • Plant trees to shade your house during summer • Set water heater no higher than 49°C (120°F) • Wash laundry in warm or cold water • Use low-flow shower head Solutions: Dealing with the Threat of Climate Change Options Do nothing Do more research Act now to reduce risks Precautionary principle Solutions Global Warming Prevention Cut fossil fuel use (especially coal) Shift from coal to natural gas Improve energy efficiency Shift to renewable energy resources Transfer energy efficiency and renewable energy technologies to developing countries Cleanup Remove CO2 from smokestack and vehicle emissions Store (sequester) CO2 by planting trees Sequester CO2 deep underground Sequester CO2 in soil by using no-till cultivation and taking crop land out of production Reduce deforestation Use more sustainable agriculture Limit urban sprawl Reduce poverty Slow population growth Sequester CO2 in the deep ocean Repair leaky natural gas pipelines and facilities Use feeds that reduce CH4 emissions by belching cows Reducing Greenhouse Gas Emissions Kyoto Treaty (1997) U.S. withdraws from Kyoto Treaty (2001) Other reductions in CO2 Loss of the Ozone Layer: Reasons for Concern Increased incidence and severity of sunburn Increase in eye cataracts Increased incidence of skin cancer Immune system suppression Increase in acid deposition Lower crop yields and decline in productivity When did it all begin? • Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group. • They were monitoring the atmosphere above Antarctica from a research station Research Station in Antarctica The Atmosphere • Where and how ozone is formed? • Ozone (O3) forms a layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles. • It is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating (or "splitting") oxygen molecules (O2) to atomic oxygen (O). • The atomic oxygen quickly combines with further oxygen molecules to form ozone (O3 ) Where is the Ozone “hole” ? • Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted at certain times of the year. • This is mainly due to the release of man-made chemicals containing chlorine such as CFC's (Chlorofluorocarbons), but also compounds containing bromine, other related halogen compounds and also nitrogen oxides (NOx). Ozone Depleting Chemicals Chlorofluorocarbons (CFCs) Halons Methyl bromide Carbon tetrachloride Methyl chloroform Hydrogen chloride Former Uses of CFCs Air Conditioners Refrigerators Spray cans Cleaners for electronic parts Sterilizing medical instruments Fumigants for granaries and cargo ships CFC’s in the air Ozone Depletion in the Stratosphere Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2. Sun Cl Cl C F Cl UV radiation Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. Cl Cl O O The chlorine atom attacks an ozone (O3) molecule, pulling an oxygen atom off it and leaving O O O an oxygen molecule (O2). Cl Summary of Reactions CCl3F + UV Cl + CCl2F Cl + O3 ClO + O2 Repeated Cl + O Cl + O2 many times A free oxygen atom pulls the oxygen atom off the chlorine monoxide Cl molecule to form O2. O O Cl The chlorine atom and the O oxygen atom join O to form a chlorine monoxide molecule O (ClO). Seasonal Ozone Layer Thinning at the Poles Ozone thinning (hole) Polar vortex January 1995 October 1995 It’s getting bigger…….. • Satellite measurements in September 2000 revealed that the stratospheric ozone “hole” over the Antarctic had a reached a record 28.3 million square kilometers (some one million sq. km more than the previous record, in 1998). October 1980- October 2002 Total ozone (Dobson units) 400 October monthly means 350 300 250 200 150 100 1955 1960 1965 1970 1975 1980 Year 1985 1990 1995 2000 2005 35 August 6, 2003 30 October 11, 2003 Altitude (kilometers) 25 20 15 10 5 0 5 10 15 Ozone partial pressure (milipascals) Natural Capital Degradation Effects of Ozone Depletion Human Health • Worse sunburn • More eye cataracts • More skin cancers • Immune system suppression Food and Forests • Reduced yields for some crops • Reduced seafood supplies from reduced phytoplankton • Decreased forest productivity for UV-sensitive tree species Wildlife • Increased eye cataracts in some species • Decreased population of aquatic species sensitive to UV radiation • Reduced population of surface phytoplankton • Disrupted aquatic food webs from reduced phytoplankton Air Pollution and Materials • Increased acid deposition • Increased photochemical smog • Degradation of outdoor paints and plastics Global Warming • Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases What are some of the dangers associated with the ozone hole? • Experts predict that an estimated 10 % reduction in the ozone layer will result in a 25% increase in non-melanoma skin cancer rates for temperate latitudes by the year 2050. Skin Cancers Melanoma Squamous Cell Carcinoma Basal Cell Carcinoma Ultraviolet A Ultraviolet B Thin layer of dead cells Hair Epidermis Squamous cells Basal layer Sweat gland Melanocyte cells Dermis Basal cell Blood vessels Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma What Can You Do? Reducing Exposure to UV-Radiation • Stay out of the sun, especially between 10 A.M. and 3 P.M. • Do not use tanning parlors or sunlamps. • When in the sun, wear protective clothing and sun– glasses that protect against UV-A and UV-B radiation. • Be aware that overcast skies do not protect you. • Do not expose yourself to the sun if you are taking antibiotics or birth control pills. • Use a sunscreen with a protection factor of 15 or 25 if you have light skin. • Examine your skin and scalp at least once a month for moles or warts that change in size, shape, or color or sores that keep oozing, bleeding, and crusting over. If you observe any of these signs, consult a doctor immediately. Skin Cancer Fact Sheet • Over half of all new cancers are skin cancers. An estimated 10,250 people will die of skin cancer this year. • More than 1 million new cases of skin cancer will be diagnosed in the United States this year. One person dies of melanoma every hour. More Facts • At current rates one in 37 Americans have a lifetime risk of developing melanoma and one in 65 Americans have a lifetime risk of developing invasive melanoma. • The incidence of melanoma more than tripled among Caucasians between 1980 and 2003. • More than 77 percent of skin cancer deaths are from melanoma. Solutions: Protecting the Ozone Layer CFC substitutes Montreal Protocol Copenhagen Protocol Abundance (parts per trillion) 15,000 No protocol 12,000 1987 Montreal Protocol 9,000 6,000 1992 Copenhagen Protocol 3,000 0 1950 1975 2000 2025 Year 2050 2075 2100