Chapter 21 Global Warming and Ozone Loss

An Enormous Cloud of Air Pollutants and Ash from Mt. Pinatubo on June 12, 1991

Global Warming and Global Cooling Are Not New (1) Over the past 4.7 billion years the climate has been altered by –Volcanic emissions –Changes in solar input –Movement of the continents –Impacts by meteors Over the past 900,000 years –Glacial and interglacial periods

Global Warming and Global Cooling Are Not New (2) Over the past 10,000 years –Interglacial period Over the past 1,000 years –Temperature stable Over the past 100 years –Temperature changes; methods of determination

Fig. 19-2, p. 498 Stepped Art

Our Climate, Lives, and Economies Depend on the Natural Greenhouse Effect Without the natural greenhouse effect –Cold, uninhabitable earth

Science: Ice Cores Are Extracted by Drilling Deep Holes in Ancient Glaciers

Human Activities Emit Large Quantities of Greenhouses Gases (1) Since the Industrial Revolution –CO 2, CH 4, and N 2 O emissions higher –Main sources: agriculture, deforestation, and burning of fossil fuels Correlation of rising CO 2 and CH 4 with rising global temperatures Countries with the largest CO 2 emissions

Fig. 19-4, p. 500 Stepped Art

A. Major Greenhouse Gases: H 2 O, CO 2, CH 4, N 2 O, CFC’s 1. P 500, graphs (y-axis: ppm, ppb) a) CO 2 and temperature change 1) fluctuation due to more photosynthesis in summer b) methane and nitrous oxide concentrations have dramatically increased also

c) Methane 1) from landfills, anaerobic decomposition (swamps, rice paddies, termites, cows), leaks in pipeline 2) 25X more effective than CO 2 per molecule (then, why is CO 2 most important greenhouse gas?) 3) can last 9-15 years in troposphere 4) methane hydrate (stable complex below tundra, in deep ocean)

d) nitrous oxide (N 2 O) 1) traps heat in troposphere and depletes ozone in stratosphere 2) released from nylon production, burning biomass and coal, breakdown of nitrates (fertilizer, waste) 3) 230 X more effective than CO 2 per molecule 4) lasts 120 years [perfluorcarbons (CF 4 ) are also greenhouse gases (from Al production)]

CO 2 Emissions B. Developed countries produce 60% of CO 2 emissions from human activities (mostly from fossil fuels) 1. China, US, EU, Indonesia, Russia, Japan, India

The Atmosphere Is Warming Mostly Because of Human Activities (1) Intergovernmental Panel on Climate Change (IPCC) –90–99% likely that lower atmosphere is warming –1906–2005: Ave. temp increased about 0.74˚C –1970–2005: Annual greenhouse emissions up 70% –Past 50 years: Arctic temp rising almost twice as fast as the rest of the earth –Melting of glaciers and floating sea ice –Prolonged droughts: increasing –Last 100 years: sea levels rose 10–20 cm

Computer models predict greenhouse warming 1. most sophisticated climate models are general circulation models (GCM) a) take greenhouse gases, ocean circulation, aerosols from volcanoes and from pollutants b) one idea shows a series of models in sequence, starting with greenhouse effect

Fig. 19-A, p. 502 Sun Troposphere Cooling from increase Aerosols Greenhouse gases Warming from decrease CO 2 removal by plants and soil organisms CO 2 emissions from land clearing, fires, and decay Heat and CO 2 removal Heat and CO 2 emissions Ice and snow cover Shallow ocean Land and soil biota Long-term storage Natural and human emissions Deep ocean

Antarctica Greenland Ocean currents transport heat Gulf Stream blocked by cold, fresh water (less dense) “Day after Tomorrow”

Is a Hotter Sun the Culprit? Since 1975 –Troposphere has warmed –Stratosphere has cooled This is not what a hotter sun would do

Can the Oceans Save Us? Solubility of CO 2 in ocean water Warmer oceans –CO 2 levels increasing acidity –Effect on atmospheric levels of CO 2 –Effect on coral reefs Antarctica’s Southern Ocean and the North Atlantic Ocean –Decrease in CO 2 uptake –Significance on global CO 2 levels

There Is Uncertainty about the Effects of Cloud Cover on Global Warming Warmer temperatures create more clouds –Thick, light-colored low altitude clouds: decrease surface temperature –Thin, cirrus clouds at high altitudes: increase surface temperature Effect of jet entrails on climate temperature

Ice core analysis (air trapped in bubbles in glaciers) shows: a) water vapor concentration has stayed constant b) [CO 2 ] 280 ppm 364 ppm see graph p 465 1) CO 2 level corresponds to temperature levels during past 160,000 yrs -humans appeared 60,000 years ago

7. Average Temperature average temperature rose 0.3% ( ) was hottest half decade (2005 was hottest year) , ocean level rose inches

E. Future 1. Intergovernmental panel on climate change (IPCC) states mean temperature will rise o C between 1990 to northern hemisphere warms faster (more land) 3. as temperature rises, evaporation rises, precipitation increases, more heavy rains and snows 4. due to expansion mostly, ocean level will rise 19 inches ( )

4. Clouds and Albedo a) warming (absorb and reflect heat: high cirrus clouds) or cooling (shade: low cumulus clouds) effect b) albedo: ability to reflect light off earth’s surface 1) melting ice cap reduces albedo ---> temp up (pos fbk loop)

7. human response a) temp up ---> air cond up ---> fossil fuel consump up ---> CO 2 up

G. Effects of a Warmer World 1. if slow ---> relocate, if too fast ---> no time to relocate 2. climate bands move north a) ok for humans if... 1) soil is good for farming 2) money is avail for infrastructure (storage, irrigation) b) N.A. ---> Canada... no China ---> north... yes Ukraine ---> Siberia... no

Melting of Alaska’s Muir Glacier between 1948 and 2004

Sea Levels Are Rising (1) Expansion of warm water Melting of land-based ice What about Greenland?

Science Focus: Melting Ice in Greenland Largest island: 80% composed of glaciers 10% of the world’s fresh water 1996–2007: net loss of ice doubled Effect on sea level if melting continues

More Effects 3. rising sea level ---> flood productive productive wetlands 4. increasing ocean temp ---> destroy coral reefs 5. lakes, streams dry up ---> pop moves 6. trees may not be able to move north fast enough 7. drying ---> wildfires 8. biodiversity down b/c no time for migration 9. rising sea level ---> lowlands and deltas in China. India and Bangladesh flooded a) Netherlands needs $ 3-5 trillion to raise dikes

Sea Levels Are Rising (2) Projected irreversible effect –Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs –Disruption of coastal fisheries –Flooding of Low-lying barrier islands and coastal areas Agricultural lowlands and deltas –Contamination of freshwater aquifers –Submergence of low-lying islands in the Pacific and Indian Oceans and the Caribbean

Low-Lying Island Nation: Maldives in the Indian Ocean

Permafrost Is Likely to Melt: Another Dangerous Scenario Carbon present as CH 4 in permafrost soils and lake bottoms 2004: Arctic Climate Impact Assessment –10–20% of the permafrost might melt this century Effect on global warming

Extreme Weather Will Increase in Some Areas Heat waves and droughts in some areas Prolonged rains and flooding in other areas Will storms get worse? –More studies needed Hurricanes Katrina and Rita

Climate Change Will Shift Areas Where Crops Can Be Grown Regions of farming may shift –Decrease in tropical and subtropical areas –Increase in northern latitudes Less productivity; soil not as fertile Genetically engineered crops more tolerant to drought

H. Solutions 1. expensive to deal with a) boiled frog syndrome: frog won’t complain until it is too late 2. CO 2 from natural gas per joule = 1/2 CO 2 from coal per joule 3. phase out gov subsidies, phase in carbon tax on coal and oil a) based on CO 2 emissions b) reduce other taxes to compensate c) sell greenhouse gas emission credits

Solutions cont. 4. provide energy conserv tech to dev countries a) solar cookers 5. technofixes a) add iron to oceans ---> algae pop. up ---> photosyn up ---> $ billions/yr b) inject sulfate particulates (like volcanic erupt) ---> pollution, O 3 destruction

Avoiding Catastrophe: We Can Reduce the Threat of Climate Change (3) Output solutions –Massive global tree planting; how many? Wangari Maathai (Green Belt Movement) Great Wall of Trees: China and Africa –Plant fast-growing perennials on degraded land –Capturing and storing CO 2 (sequestration)

Some Output Methods for Removing CO 2 from the Atmosphere and Storing It

Case Study: Is Capturing and Storing CO 2 the Answer? (1) Carbon capture and storage (CCS) Several problems with this approach –Power plants using CCS More expensive to build None exist –Unproven technology –Large inputs of energy to work Increasing CO 2 emissions

Case Study: Is Capturing and Storing CO 2 the Answer? (2) Problems with carbon capture and storage cont… –Promotes the continued use of coal (world’s dirtiest fuel) –Effect of government subsidies and tax breaks –Stored CO 2 would have to remain sealed forever: no leaking

Governments Can Help Reduce the Threat of Climate Change Strictly regulate CO 2 and CH 4 as pollutants Cap-and-trade approach Increase subsidies to encourage use of energy-efficient technology Technology transfer

Some Companies and Schools Are Reducing Their Carbon Footprints (1) Major global companies reducing greenhouse gas emissions –Alcoa –DuPont –IBM –Toyota –GE –Wal-Mart (Fluorescent light bulbs, Auxiliary power units on truck fleets)

Some Companies and Schools Are Reducing Their Carbon Footprints (2) Colleges and universities reducing greenhouse gas emissions –Oberlin College, Ohio, U.S. –25 Colleges in Pennsylvania, U.S. –Yale University, CT, U.S. What is your carbon footprint? What can you do?

Kyoto Protocol 161 nations met in 1997 Requires cutting of emissions of CO 2, CH 4, and N 2 O to 5.2% below 1990 levels by 2012 Ratified by120 countries by 2004 In 2001, Bush withdraws US from treaty b/c too expensive, China, etc are exempt

What is being done Great Britain has reached Kyoto goal China has reduced CO 2 emissions BP, DuPont, Toyoto, IBM have established CO 2 emission targets 500 cities (110 in US) have established programs to reduce greenhouse gas emissions

Ozone Depletion in the Stratosphere Less ozone in the stratosphere allows more UV radiation to reach the earth’s surface CFCs are inert, long-lived, and inexpensive In 1974 Rowland and Molina (1995 Nobel Prize in chemistry) found that CFCs were lowering ozone concentrations Ozone Hole (thinning) occurs during 4 month period over Antartica

CFC’s 1) deplete ozone in stratosphere 2) global warming in the troposphere ( times more effective than CO 2 per molecule 3) main sources: from leaking air conditioners, refrigerators, styrofoam, propellants in developing countries 4) lasts in stratosphere yrs 5) Montreal Protocol 36 nations in 1987 agree to phase out CFC’s, deadlines moved up at subsequent meetings (Copenhagen Protocol)

Polar Vortex Swirling mass of air, isolated from rest of atmosphere, collects CFCs In Antarctic spring, CFCs and sunlight produce ClO leading to rapid destruction of ozone, O 3. Affects Australia.

UV Radiation Causes skin cancer: squamous cell, basal cell, and melanoma (highest fatality) Tanning parlors increase incidence of melanoma

Montreal Protocol 1987, 36 countries met Cut CFC emissions by 35% between 1989 and Copenhagen Protocol, 1992, accelerated phasing out (signed by 177 countries) Example of global cooperation

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl 3, breaking off a chlorine atom and leaving CFCl 2. UV radiation Sun Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O 2. The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). The chlorine atom attacks an ozone (O 3 ) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O 2 ). Cl C F O O O O O O O O O O Summary of Reactions CCl 3 F + UV Cl + CCl 2 F Cl + O 3 ClO + O 2 Cl + O Cl + O 2 Repeated many times

Antarctic

Arctic