Presentation on theme: "G. Tyler Millers Living in the Environment Chapter 18 Climate Change and Ozone Loss."— Presentation transcript:
G. Tyler Millers Living in the Environment Chapter 18 Climate Change and Ozone Loss
Key Concepts Changes in Earths 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
Temperature and climate have been changing throughout the earths 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. Past Climate Changes Antarctic ice cores indicate the current interglacial period could last another 15,000 years.Antarctic ice cores indicate the current interglacial period could last another 15,000 years. Direct temperature records go back to 1861.Direct temperature records go back to The Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 to evaluate possible future climate changes.The Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 to evaluate possible future climate changes.
Past Climate Changes Past global temperatures Recent trends in global temperatures Todays global average temp 59 o F, 15 o C
The Earths 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 earths surface due to heat absorbed by surface water. Provides an natural cooling effect on earth The earths 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
What is the Greenhouse Effect Fig: 6-14
Table 21-1 Page 464 Table 21-1 Major Greenhouse Gases from Human Activities Greenhouse Gas Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Chlorofluorocarbons (CFCs)* Hydrochloro- fluorocarbons (HCFCs) Hydrofluorocarbons (HFCs) Halons Carbon tetrachloride Average Time in the Troposphere 100–120 years 12–18 years 114–120 years 11–20 years (65–110 years in stratosphere) 9–390 15– Human Sources Fossil fuel burning, especially coal (70– 75%), deforestation, and plant burning Rice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelines Fossil fuel burning, fertilizers, livestock wastes, and nylon production Air conditioners, refrigerators, plastic foams Fire extinguishers Cleaning solvent Relative Warming Potential (compared to CO 2 ) –8, –2, –12,700 5,500 1,400
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.
Estimated long term varation in average global temp. of the atmosphere and average CO2 levels in past 160,00 years.
U.S. and Greenhouse Gases 4.6% of the worlds population, yet 24% of emissions of CO2 From just U.S. coal burning exceeds 146 other nations with 3/4 th of world population Per capita yearly 500 tons Also large CH 4
Is the troposphere warming? There is considerable and mounting evidence that the troposphere is warming quickly Rate of change IPCC found: 1) 20 th Century warmest in past 1,000 years
Is the troposphere warming? 2) Since 1861 global avg. temp increase C or F (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 pronounced 5) Global sea levels rose 4-8 inches during 20 th Century and continue to rise.
Is the troposphere warming? Few skeptics still exist, most just argue it is not human caused warming Global warming versus Global climate change--- what is the difference? Do NOT confuse it with ozone depletion
New Terminologies Global warming refers to temperature increases in the troposphere, which can cause climate change.Global 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 earths climate.Global climate change is a broader term that refers to changes in any aspects of the earths climate.
Factors Affecting the Earths Temperature Changes in solar output Changes in Earths albedo Moderating effect of oceans Clouds and water vapor Air pollution
Oceans 5% Bare sand 30–60% Grass 15–25% Clouds 50–55% Snow 80–90% City 10–15% Forest 5% Figure: The Albedo or reflectivity of the incoming solar energy.
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?
Warning Signals From Glaciers Mount Kilimanjaro glacier free in 15 years? 80% of South American glaciers gone also in 15 years? Less fresh water sources Tourism loss Any good impacts?
Projecting Future Changes in Earths Climate Climate models Apparent influence of human activities Apparent influence of human activities Could be natural changes Could be natural changes
Climate models Scientists have developed complex mathematical models of the earths climate system. Inputs: Solar energy Earths land Ice Greenhouse gases Clouds, winds, water vapor
Troposphere Aerosols Greenhousegases Warmingfromdecrease Cooling from increase CO 2 removal by plants and soil organisms CO 2 emissions from land cleaning, fires, and decay Heat and CO 2 removal Heat and CO 2 emissions Ice and snow cover Natural and human emissions Land and soil Shallow ocean Long-termstorage Deep ocean
IPCC Reports Best Science IPCC (Intergovernmental Panel on Climate Change) 1990, 1995, 2001 and now 2007 reports Three Major Finding From ) Latest climate models closely match changes since 1850
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 1.4 o C to 5.8 o C (2.5 o F to 10.4 o F) between 2000 and 2100
Ocean Storage of CO 2 and Heat Ocean currents act to redistribute heat arriving at equator moving it north. Example: Gulf Stream Deep ocean currents not well understood.
Ocean Storage of CO 2 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…
Ocean Storage of CO 2 and Heat Oceans also act to trap about 29% of CO 2 released into the atmosphere as part of global carbon cycle.
Cloud Cover Warmer Troposphere = More Evaporation = More Clouds = WARMER OR COOLER? Why might it be a positive feedback? Why might it be a negative feedback?
Cloud Cover Day versus Night Impacts Thick clouds versus thin clouds High clouds versus Low clouds Latent heat release during cloud formation
Possible Benefits from a Warmer Atmosphere Less severe wintersLess severe winters More precipitation in some dry areasMore precipitation in some dry areas Less precipitation in some wet areasLess precipitation in some wet areas Increased food production in some areasIncreased food production in some areas Expanded population and ranges of some speciesExpanded population and ranges of some species
Some Possible Effects of a Warmer World
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;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; anddeveloped countries, developing countries, or both should take responsibility for reducing greenhouse gases; and actions to reduce greenhouse gas emissions should be voluntary or required.actions to reduce greenhouse gas emissions should be voluntary or required. Four schools of thought have emerged from this controversy.
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?
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….
Solutions: Dealing with the Threat Options Do nothing Do more research Act now to reduce risks Precautionary principle
What can be done? Improve energy efficiency Reduce fossil fuel use Renewable energy sources Reduce population growth Reduce deforestation Carbon sequestration
Treeplantation Coal power plant Tanker delivers CO 2 from plant to rig Oil rig Crop field Switchgrass Spent oil reservoir is used for CO 2 deposit CO 2 is pumped down to reservoir through abandoned oil field Abandoned oil field CO 2 is pumped down from rig for deep ocean disposal = CO 2 deposit = CO 2 pumping Removing CO 2 from the Atmosphere
Reducing CO 2 Emissions What Can You Do? Drive a fuel-efficient car, walk, bike, carpool, Drive a fuel-efficient car, walk, bike, carpool, and use mass transit and use mass transit Use energy-efficient windows Use energy-efficient windows Use energy-efficient appliances and lights Use energy-efficient appliances and lights Heavily insulate your house and seal all drafts Heavily insulate your house and seal all drafts Reduce garbage by recycling and reuse Reduce garbage by recycling and reuse Insulate hot water heater Insulate hot water heater Use compact fluorescent bulbs Use compact fluorescent bulbs Plant trees to shade your house during summer Plant trees to shade your house during summer Set water heater no higher than 49°C (120°F) Set water heater no higher than 49°C (120°F) Wash laundry in warm or cold water Wash laundry in warm or cold water Use low-flow shower head Use low-flow shower head
Figure Page 483
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.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 Developing countries would not have to make cuts until a later date.Developing countries would not have to make cuts until a later date. By mid-2004, it had been ratified by more than 120 countries.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.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.Scott Barnett, an expert on environmental treaties, believes the Kyoto Protocol is a badly thought out agreement and it will not work.
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 Estimates are that current emissions of greenhouse gases must be cut by at least 50% by 2018 to stabilize concentrations at their present levels.
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
Long-lived chemicals and ozone level 1.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).
Ozone Depleting Chemicals Chlorofluorocarbons (CFCs) Halons(used in fire extinguishers) Methyl bromide (dry cleaning) Carbon tetrachloride Methyl chloroform Hydrogen chloride
Former Uses of CFCs Air ConditionersAir Conditioners RefrigeratorsRefrigerators Spray cansSpray cans Cleaners for electronic partsCleaners for electronic parts Sterilizing medical instrumentsSterilizing medical instruments Fumigants for granaries and cargo shipsFumigants for granaries and cargo ships
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.
The polar vortex is a swirling mass of very cold air that is isolated from the rest of the atmosphere for several months.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.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.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.It is predicted that the worst ozone thinning will be between 2010 and 2019.
Increased UV radiation reaching the earths 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.
Effects of Ozone Depletion Natural Capital Degradation 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
Solutions: Protecting the Ozone Layer CFC substitutes Montreal Protocol : 1987; 35 nations to cut CFC by 35% in 2000 Copenhagen Protocol: phase out of all ozone depleting chemicals
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 levels. The goal of the 1987 Montreal Protocol was to cut emissions of CFCs by about 35% between 1989 and 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.