Chapter 19 Global Warming & Ozone Loss © Brooks/Cole Publishing Company / ITP Tuesday 3/29/11 1) 2) 3) 4) 5) 6) Inconvenient Truth Review Current Event – Global Warming & Coffee Phet – Molecules & Light Compare Global Warming & Ozone Loss Sticky Analysis of CFCs & Skin Cancer Compare Kyoto vs Montreal Protocols Electromagnetic Spectrum Black Body Radiation Earth radiation magnified 500x Infrared Absorbance of CO2 Infrared Absorbance of Water Infrared Absorbance of CH4 Infrared Absorbance of N2O Absorbance Simulation of Gases http://phet.colorado.edu/en/simulation /molecules-and-light Table 18-1 Problem Comparison Green House Effect Ozone Shield Where in the Atmosphere? Troposphere 0-17 miles up Stratosphere 11-30 miles up What process occurs? Traps infrared (IR) heat near surface Filters ultraviolet (UV) radiation from the Sun Oxygen O2, ozone O3 What natural gases H2O, CO2, are involved? CH4 (methane) What are important CO2, CH4, CFCs, CFCs, halons, human inputs? N2O (nitrous oxide) CCl4, etc. What problems result? Global warming, rising sea levels Ozone depletion, skin cancers International Reports • http://www.ipcc.ch/ipccreports/assessments -reports.htm • IPCC Reports on Global Warning Issue Activities • Your Contribution to Global Warming • Sea Level Rises – Topography • An Inconvenient Truth An Inconvenient Truth It ain’t what you don’t know that gets you into trouble, it’s what you know that just ain’t so. Mark Twain Green House Gases 1. What are greenhouse gases and what processes produce them? • 80% CO2 – burning fossil fuels • CH4, methane – livestock manure, • N2O, nitrous oxide – fuel burning, crop & forest burning • SF6, PFCs, HCFCs – industrial processes Green House Effect 2. How do greenhouse gases cause global warming? • See page 28 & 29 of AIT • Solar energy reaches the Earth. • The Earth re-radiates some as infrared, IR. • Green house gases like CO2 absorb IR before it escapes and hold the energy in the atmosphere. • As green house gases accumulate in the atmosphere, more & more energy is trapped in the atmosphere. Atmospheric CO2 Concentrations (1 of 2) 3. Scientists have measured atmospheric CO2 concentration from 1958 to today. What has been the trend in global atmospheric CO2 concentration over the past 50 years since scientists started directly measuring it? • See page 36 & 37 • determine slope of steady increase • m = (380-315)ppm/ (2005-1958)yr • = 65/47 ppm/yr = 1.4 ppm/yr • 381ppm in 2005 vs 280 ppm baseline, % increase? • 381/280 = 136% or a 36% increase. Atmospheric CO2 Concentrations (2 of 2) 3. Why does the line go up and down each year? See pages 32-35 • Most of the Earth’s land mass is in the Northern Hemisphere. • During the Spring & Summer the Northern Hemisphere draws in CO2 during its growing season. • During the Fall & Winter the Northern Hemisphere releases CO2 as plants slow photosynthesis and a lot decomposes. • The Southern Hemisphere has a much smaller effect. Historical CO2 vs Temperature 4. What is the relationship between global atmospheric CO2 concentrations and mean global atmospheric temperature over the past 600,000 years? Gore says this is like the fit of South American and African continents; explain what he means by this. • See page 66 & 67. • Antarctic ice core measurements show that global temperatures closely mirror global CO2 levels. Cyclical Pattern? 5. Explain the evidence that suggests that the warming period we are in is not just part of a "natural cyclical phenomenon". • See page 64 & 65. • Over the last 1000 years, glacial ice cores show 3 previous warming periods, none of them compare to the present warming period in persistence or intensity. • See page 67. • The present CO2 levels far exceed any CO2 levels measured over the past 650,000 years and they continue to climb steeply. Winston Churchill 1936 The era of procrastination, of half-measures, of soothing and baffling expedients, of delays, is coming to a close. In its place we are entering a period of consequences. What was he talking about? Hitler’s Nazi Invasions How does this relate to global warming? The consequences of global warming are already impacting our world. Effects of Global Warming A. Melting of floating sea ice & impacts 1. Minimal sea level change ( page 142 & 143) • Only 1/8 of sea ice is above the sea level. 2. Polar bear populations (and others) page 147 • Polar bears depend on diminishing ice pack for seal hunting grounds. They are drowning at record rates. 3. Acceleration of global warming due to changes in sunlight reflection & absorption (see page 145) • Sea ice reflects sunlight and minimizes absorption. • Melted sea ice exposes sea water which absorbs sunlight, heats up and melts the sea ice even faster in a __________ feedback loop. Outline 1. Natural Global Processes • What is the greenhouse effect? • What is the ozone shield? 2. What Problems Result from Human Inputs • Global warming • Ozone depletion 3. Solutions 4. Summary © Brooks/Cole Publishing Company / ITP pollution – undesirable change in physical, chemical, or biological characteristics of air, water, soil, or food that can adversely affect humans or other living organisms. Fig. 18–3 © Brooks/Cole Publishing Company / ITP 1. Natural Global Processes • Greenhouse Effect • Ozone Shield • Questions – What? – Where? – Gases involved? – Human inputs? – What problems result? © Brooks/Cole Publishing Company / ITP What is the Greenhouse Effect? Greenhouse Effect: a natural process that traps heat near the Earth’s surface. • short wave radiation in • long wave radiation out • re-radiation downward by “greenhouse gases” in atmosphere Fig. 4–7 © Brooks/Cole Publishing Company / ITP Human inputs? c) CH4 (continued) Greenhouse Effect: • methane (CH4) • nitrous oxide (N2O) d) N2O Fig. 19–2 c & d © Brooks/Cole Publishing Company / ITP 2. What Problems Result from Human Inputs? • Global Warming • Ozone Depletion • Questions – Are they proven? – What are potential consequences? – What can be done? © Brooks/Cole Publishing Company / ITP How Does This Relate to the Carbon Cycle? • Sources of Increased Atmospheric CO2 – Burning Fossil Fuels (see Fig. 5–5) – Deforestation • Carbon Balance: increased atmospheric CO2 less than expected based only on input – about 49% remains in atmosphere – about 29% uptake by oceans – carbon balance: about 22% unaccounted for © Brooks/Cole Publishing Company / ITP Consequences of Increased Greenhouse Gases Fig. 19–6 © Brooks/Cole Publishing Company / ITP Climate Changes During Past 900,000 Years Fig. 19–3 • Past climate based on study of Antarctic glaciers • Cycles of Ice Ages lasting about 100,000 years • Interglacial Periods lasting 10,000 to 12,500 yrs © Brooks/Cole Publishing Company / ITP Climate During Past 160,000 Years • End of last ice age about 10,000 yr BP • Now in warm interglacial period • Based on ice core data, analysis of trapped gas • Correlation between CO2 & mean temperature Fig. 19–4 © Brooks/Cole Publishing Company / ITP What is the Scientific Consensus? • Mean global temperature rose about 0.6º C (1º F) in past 100 years • Increase is real, not explained by natural variation in solar radiation • Warming greater at poles than equator, greater at night, mostly Fig. 19–5 troposphere © Brooks/Cole Publishing Company / ITP Future Scenarios General Circulation Models (GMCs) used to predict future climate • Projected warming of 1 to 3.5 º C between 1990 & 2100 • Likely scenario: doubling of CO2 (from 280 ppm to 560 ppm) before 2100 leading to warming of 2º C Fig. 19–5 © Brooks/Cole Publishing Company / ITP Role of Ocean • Storage of CO2 in deep water • Warming could decrease ability of ocean to serve as “sink” for carbon Fig. 19–7 © Brooks/Cole Publishing Company / ITP Ecological Implications • Shift of habitat to higher latitudes • Shift of habitat to higher elevations • Potential large loss of biodiversity Fig. 19–8 © Brooks/Cole Publishing Company / ITP 3. Solutions Solutions to Global Warming Fig. 19–9 © Brooks/Cole Publishing Company / ITP Solutions to Global Warming Fig. 19–10 © Brooks/Cole Publishing Company / ITP Human inputs? a) CO2 Greenhouse Effect: • carbon dioxide (CO2) – 75% developed countries – 22% U.S. b) CFCs • chlorofluorocarbons (CFCs) Fig. 19–2 a & b © Brooks/Cole Publishing Company / ITP Where? • Greenhouse Effect: • in troposphere • Ozone Shield: • in stratosphere 11-16 miles up What is the Ozone Shield? Ozone Shield: a natural process that filters ultraviolet (UV) radiation before it reaches the lower atmosphere. Human inputs? • Ozone Shield: • Chlorofluorocarbons (CFCs) • other stable halogen–containing gases (halogens = chlorine, fluorine, & bromine) b) CFCs What Natural Gases? •Greenhouse Effect: water H2O carbon dioxide CO2 methane CH4 •Ozone Shield: oxygen O2 ozone O3 © Brooks/Cole Publishing Company / ITP How Does Depletion Occur? • CFCs stable, move from troposphere to stratosphere • UV breaks off chlorine molecule (Cl) from CFC • Cl acts as a catalyst to break down ozone (O3) – catalyst – promotes a chemical reaction without itself being used up in the reaction – shifts equilibrium of oxygen / ozone reaction: O2 O3 © Brooks/Cole Publishing Company / ITP How Does Depletion Occur? Fig. 19–12 © Brooks/Cole Publishing Company / ITP Consequences of Ozone Depletion • Increase in skin cancer & cataracts, especially in southern hemisphere • More ozone near earth’s surface, produced in photochemical smog – lung problems, suppressed immune response, cancer © Brooks/Cole Publishing Company / ITP What are the Consequences of Increased Ozone Depleting Gases What are the Consequences of Ozone Depletion? • Increase in skin cancer & cataracts, especially in southern hemisphere • More ozone near earth’s surface, produced in photochemical smog – lung problems, suppressed immune response, cancer What is the Ozone Hole? • Seasonal thinning of the ozone layer has resulted at the poles, especially in the southern hemisphere. • Recent models suggest the hole may not get larger. Comparing Ozone Loss How does the ozone loss over the North Pole compare to the South Pole? Projected total ozone loss, averaged over 2010-2019, during September for the Antarctic (left) and during March for the Arctic (right). According to the model used to make these projections, during this period the severity of ozone loss over the Arctic may approach that over the Antarctic. Dark red represents ozone depletion of 54% or more; light blue, 1830%; dark blue, 6-12%. Solutions to Ozone Depletion • phase out use of ozone–depleting chemicals – halons, CFCs, methyl chloroform, methyl bromide • phase in use of CFC substitutes – non–halogen aerosol propellants, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), hydrocarbons (HCs), ammonia, water & steam, terpenes, helium Summary Problem Comparison Green House Effect Ozone Shield Where in the Atmosphere? Troposphere 0-11 miles up Stratosphere 11-30 miles up What process occurs? Traps infrared (IR) heat near surface Filters ultraviolet (UV) radiation from the Sun Oxygen O2, ozone O3 What natural gases H2O, CO2, are involved? CH4 (methane) What are important CO2, CH4, CFCs, CFCs, halons, human inputs? N2O (nitrous oxide) CCl4, etc. What problems result? Global warming, rising sea levels Ozone depletion, skin cancers