Presentation on theme: "G. Tyler Miller’s Living in the Environment Chapter 18"— Presentation transcript:
1 G. Tyler Miller’s Living in the Environment Chapter 18 Climate Change and Ozone LossG. Tyler Miller’s Living in the Environment Chapter 18
2 Key Concepts Changes in Earth’s climate over time Factors affecting climatePossible effects of global warmingAdapting to climate changeHuman impacts on the ozone layerProtecting and restoring the ozone layer
3 Past Climate ChangesTemperature and climate have been changing throughout the earth’s history.Climate shifts have occurred due to volcanic emissions changes in solar input, continents moving on shifting plates, meteor strikes, and other factors.Alternating cycles of freezing and thawing are known as glacial and interglacial periods.Antarctic ice cores indicate the current interglacial period could last another 15,000 years.Direct temperature records go back to 1861.The Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 to evaluate possible future climate changes.
4 Past Climate Changes Past global temperatures Recent trends in global temperaturesToday’s global average temp 59oF, 15oC
5 The Earth’s Natural Greenhouse Effect A natural process called the greenhouse effect warms the lower troposphere and surface. Incoming solar must be balanced by equal amt. of outgoing energy.A large process also takes place at the earth’s surface due to heat absorbed by surface water. Provides an natural cooling effect on earthThe earth’s average surface temperature is about 15 degrees Celsius.(59 F)The two major greenhouse gases are water vapor and carbon dioxide. Water vapor has remained constant. Carbon dioxide has fluctuated ppm
7 Table 21-1 Major Greenhouse Gases from Human Activities Table 21-1 Page 464Greenhouse GasCarbon dioxide (CO2)Methane (CH4)Nitrous oxide (N2O)Chlorofluorocarbons(CFCs)*Hydrochloro-fluorocarbons (HCFCs)Hydrofluorocarbons(HFCs)HalonsCarbon tetrachlorideHuman SourcesFossil fuel burning, especially coal (70–75%), deforestation, and plant burningRice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelinesFossil fuel burning, fertilizers, livestock wastes, and nylon productionAir conditioners, refrigerators, plastic foamsFire extinguishersCleaning solventAverage Time in the Troposphere100–120 years12–18 years114–120 years11–20 years (65–110 years in stratosphere)9–39015–3906542Relative Warming Potential (compared to CO2)123296900–8,300470–2,000130–12,7005,5001,400
8 Climate Change and Human Activities Humans have increased levels of greenhouse gases in the troposphere by use of fossil fuels, farming, use of inorganic fertilizers, burning forests, etc.Greenhouse gases are at higher levels than in the past 160,000 years.Burning of fossil fuels has generated much of the CO2 increase.Deforestation and clearing grasslands release CO2 and N2O.Increased cattle raising, and other livestock, has added methane release.Use of inorganic fertilizers in rice cultivation releases N2O into the troposphere.
9 Estimated long term varation in average global temp. of the atmosphere and average CO2 levels in past 160,00years.
10 U.S. and Greenhouse Gases 4.6% of the world’s population, yet 24% of emissions of CO2From just U.S. coal burning exceeds 146 other nations with 3/4th of world populationPer capita yearly 500 tonsAlso large CH4
11 Is the troposphere warming? There is considerable and mounting evidence that the troposphere is warming “quickly”Rate of changeIPCC found:1) 20th Century warmest in past 1,000 years
12 Is the troposphere warming? 2) Since 1861 global avg. temp increase 0.80C or 1.40F (mostly post 1980)3) 16 of the warmest years on record occurred since 1980 (hottest 1998 followed by 2001 and 2003)4) Glaciers around world melting quickly and poles warming more pronounced5) Global sea levels rose 4-8 inches during 20th Century and continue to rise.
13 Is the troposphere warming? Few skeptics still exist, most just argue it is not human caused warmingGlobal warming versus Global climate change--- what is the difference?Do NOT confuse it with ozone depletion
14 New TerminologiesGlobal warming refers to temperature increases in the troposphere, which can cause climate change.Global climate change is a broader term that refers to changes in any aspects of the earth’s climate.
15 Factors Affecting the Earth’s Temperature Changes in solar outputChanges in Earth’s albedoModerating effect of oceansClouds and water vaporAir pollution
16 Clouds 50–55%Snow 80–90%City 10–15%Forest 5%Grass 15–25%Bare sand 30–60%Oceans 5%Figure: The Albedo or reflectivity of the incoming solar energy.
17 Warning Signals From Glaciers Positive Feedback: more ice melting = more warming = more ice melting….Melting floating ice has little impact on sea level rise (WHY?)“Fresher” water in ocean, what are the consequences?
18 Warning Signals From Glaciers Mount Kilimanjaro glacier free in 15 years?80% of South American glaciers gone also in 15 years?Less fresh water sourcesTourism lossAny good impacts?
19 Projecting Future Changes in Earth’s Climate Climate modelsApparent influence of human activitiesCould be natural changes
20 Climate modelsScientists have developed complex mathematical models of the earth’s climate system.Inputs:Solar energyEarth’s landIceGreenhouse gasesClouds, winds, water vapor
22 Natural and human emissions TroposphereCooling from increaseCO2 removal by plants and soil organismsCO2 emissions from land cleaning, fires, and decayWarmingfromdecreaseAerosolsHeat andCO2 removalHeat andCO2 emissionsGreenhousegasesIce and snow coverShallow oceanLand and soilLong-termstorageNatural and human emissionsDeep ocean
23 IPCC Reports “Best Science” IPCC (Intergovernmental Panel on Climate Change)1990, 1995, 2001 and now 2007 reportsThree Major Finding From 20011) Latest climate models closely match changes since 1850
24 IPCC Reports “Best Science” 2) “There is strong evidence that most of the warming observed over the last 50 years is attributable to human activities.”3) It is likely that the world will warm 1.4oC to 5.8oC (2.5oF to 10.4oF) between 2000 and 2100
25 Ocean Storage of CO2 and Heat Ocean currents act to redistribute heat arriving at equator moving it north.Example: Gulf StreamDeep ocean currents not well understood.
26 Ocean Storage of CO2 and Heat Evidence has shown that ocean currents have shifted and even stopped during times in the past.Effect of salinity levels (cold, salty water more dense)“Day After Tomorrow” movie effect…
27 Ocean Storage of CO2 and Heat Oceans also act to trap about 29% of CO2 released into the atmosphere as part of global carbon cycle.
28 Cloud Cover Warmer Troposphere = More Evaporation = More Clouds = WARMER OR COOLER?Why might it be apositive feedback?negative feedback?
29 Cloud Cover Day versus Night Impacts Thick clouds versus thin clouds High clouds versus Low cloudsLatent heat release during cloud formation
30 Possible Benefits from a Warmer Atmosphere Less severe wintersMore precipitation in some dry areasLess precipitation in some wet areasIncreased food production in some areasExpanded population and ranges of some species
32 Solutions: Dealing with the Threat Scientists debate the causes, how rapidly the changes might occur, the effects on humans and ecosystems, and the responses that should be taken.Economists and policymakers disagree on whether:economic costs of reducing greenhouse gas emissions are higher than the economic benefits;developed countries, developing countries, or both should take responsibility for reducing greenhouse gases; andactions to reduce greenhouse gas emissions should be voluntary or required.Four schools of thought have emerged from this controversy.
33 Dealing with the Threat of Climate Change There is little disagreement that our planet is warming, where most disagreement lies is in what to do about it.1) Are economic costs of reducing greenhouse gases higher than benefits?
34 Dealing with the Threat of Climate Change 2) Developed or developing countries, how should take responsibility?3) Voluntary cuts or mandatory laws?Arguments transcend politics, economics, scientific, cultural….
35 Solutions: Dealing with the Threat OptionsDo nothingDo more researchAct now to reduce risksPrecautionary principle
36 What can be done? Improve energy efficiency Reduce fossil fuel use Renewable energy sourcesReduce population growthReduce deforestationCarbon sequestration
38 Removing CO2 from the Atmosphere Coalpower plantTanker deliversCO2 from plantto rigOil rigTreeplantationCO2 ispumped downfrom rig for deepocean disposalAbandonedoil fieldSwitchgrassCrop fieldCO2 is pumpeddown to reservoirthrough abandoned oil fieldSpent oil reservoir isused for CO2 deposit= CO2 deposit= CO2 pumpingRemoving CO2 from the Atmosphere
39 What Can You Do?Reducing CO2 EmissionsDrive a fuel-efficient car, walk, bike, carpool,and use mass transitUse energy-efficient windowsUse energy-efficient appliances and lightsHeavily insulate your house and seal all draftsReduce garbage by recycling and reuseInsulate hot water heaterUse compact fluorescent bulbsPlant trees to shade your house during summerSet water heater no higher than 49°C (120°F)Wash laundry in warm or cold waterUse low-flow shower head
41 What is Being Done to Reduce Greenhouse Gas Emissions? The Kyoto Protocol, developed in 1997, would require 39 developed countries to cut emissions of some gases by about 5.2% below 1990 levels by 2012.Developing countries would not have to make cuts until a later date.By mid-2004, it had been ratified by more than 120 countries.In 2001, President George W. Bush withdrew the U.S. from the Kyoto Protocol.Scott Barnett, an expert on environmental treaties, believes the Kyoto Protocol is a badly thought out agreement and it will not work.
42 Many countries, companies, cities, states, and provinces are reducing greenhouse gas emissions, improving energy efficiency, and increasing their use of carbon-free renewable energy.Great Britain reduced its CO2 emissions to its 1990 level by the year 2000, well ahead of the Kyoto target goal.China reduced it CO2 emissions by 17% between 1997 and 2000 by phasing out coal subsidies, shutting down inefficient coal-fired electric plants, and restructuring its economy toward use of renewable energy resources.Some major global companies have established targets to reduce their greenhouse gas emissions by 10–65% from 1990 levels by 2010.Estimates are that current emissions of greenhouse gases must be cut by at least 50% by 2018 to stabilize concentrations at their present levels.
43 Loss of the Ozone Layer: Reasons for Concern Increased incidence and severity of sunburnIncrease in eye cataractsIncreased incidence of skin cancerImmune system suppressionIncrease in acid depositionLower crop yields and decline in productivity
44 Long-lived chemicals and ozone level The first chlorofluorocarbon (CFC) was discovered in Many use, became very popular and dream chemicals.2. In 1974, chemists Rowland and Molina found that CFCs were lowering the average concentration of ozone in the stratosphere.3. Four major conclusions from their research:a. CFCs remain in the atmosphere because they are insoluble in water and chemically unreactive.b. Over 11–20 years, these chemicals are lifted into the stratosphere, mostly by convection currents and turbulent mixing of air.c. CFC molecules break down under the influence of high-energy UV radiation. Chlorine is released and is highly reactive. Fluorine, bromine, and iodine are also released. This causes ozone to be broken down faster than it is formed.d. These CFC molecules can last in the stratosphere for 65–385 years.4. In 1988, after 14 years of delay tactics, the CFC industry acknowledged and agreed to stop manufacturing them.5. Rowland and Molina received the Nobel Prize in chemistry for their work. (1995).
45 Ozone Depleting Chemicals Chlorofluorocarbons (CFCs)Halons(used in fire extinguishers)Methyl bromide (dry cleaning)Carbon tetrachlorideMethyl chloroformHydrogen chloride
46 Former Uses of CFCs Air Conditioners Refrigerators Spray cans Cleaners for electronic partsSterilizing medical instrumentsFumigants for granaries and cargo ships
47 Seasonal Ozone Layer Thinning at the Poles During four months of each year, up to half of the ozone in the stratosphere over Antarctica is depleted.Ozone loss is often called the ozone hole, but it is actually ozone thinning.The total area of stratosphere that suffers from ozone thinning varies from year to year. In 2003, the area was the second largest ever.The primary culprits are CFCs and other ODCs.
48 The polar vortex is a swirling mass of very cold air that is isolated from the rest of the atmosphere for several months.Ice crystals in this mass collect CFCs and other chemicals and set up conditions for formation of CIO, the molecule most responsible for seasonal loss of ozone.As sunlight returns to Antarctica in October, the light stimulates CIO molecules and within a matter of weeks the ozone is reduced by 40–50% on average.It is predicted that the worst ozone thinning will be between 2010 and 2019.
49 Increased UV radiation reaching the earth’s surface from ozone depletion is harmful to human health, crops, forests, animals, and materials. Figure lists the effects of ozone depletion.Exposure to UV radiation is a major cause of skin cancers.Caucasians are most susceptible to melanomas.
51 Natural Capital Degradation Effects of Ozone Depletion Human HealthWorse sunburnMore eye cataractsMore skin cancersImmune system suppressionFood and ForestsReduced yields for some cropsReduced seafood supplies from reduced phytoplanktonDecreased forest productivity for UV-sensitive tree speciesWildlifeIncreased eye cataracts in some speciesDecreased population of aquatic species sensitive to UV radiationReduced population of surface phytoplanktonDisrupted aquatic food webs from reduced phytoplanktonAir Pollution and MaterialsIncreased acid depositionIncreased photochemical smogDegradation of outdoor paints and plasticsGlobal WarmingAccelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases
52 Solutions: Protecting the Ozone Layer CFC substitutesMontreal Protocol : 1987; 35 nations to cut CFC by35% in 2000Copenhagen Protocol: phase out of all ozone depleting chemicals
53 Protecting the Ozone Layer If we immediately stop, it will take 50 years to return to 1980 levels and about 100 years to return to pre-1950 levels.The goal of the 1987 Montreal Protocol was to cut emissions of CFCs by about 35% between 1989 and 2000.The Copenhagen Protocol, adopted in 1990 and 1992 that accelerated the phase out of key ozone-depleting chemicals.These agreements have now been signed by 177 countries.A study in 1998 stated that ozone depletion has been cooling the troposphere and helped to disguise as much as 30% of the global warming.Restoring the ozone layer could lead to increased global warming, but the alternative is worse.