Presentation is loading. Please wait.

Presentation is loading. Please wait.

G. Tyler Miller’s Living in the Environment Chapter 18

Similar presentations

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 Loss G. Tyler Miller’s Living in the Environment Chapter 18

2 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

3 Past Climate Changes Temperature 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 temperatures Today’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 earth The 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

6 What is the Greenhouse Effect
Fig: 6-14

7 Table 21-1 Major Greenhouse Gases from Human Activities
Table 21-1 Page 464 Greenhouse Gas Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Chlorofluorocarbons (CFCs)* Hydrochloro- fluorocarbons (HCFCs) Hydrofluorocarbons (HFCs) Halons Carbon tetrachloride 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 Average Time in the Troposphere 100–120 years 12–18 years 114–120 years 11–20 years (65–110 years in stratosphere) 9–390 15–390 65 42 Relative Warming Potential (compared to CO2) 1 23 296 900–8,300 470–2,000 130–12,700 5,500 1,400

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 160,00 years.

10 U.S. and Greenhouse Gases
4.6% of the world’s population, yet 24% of emissions of CO2 From just U.S. coal burning exceeds 146 other nations with 3/4th of world population Per capita yearly 500 tons Also large CH4

11 Is the troposphere warming?
There is considerable and mounting evidence that the troposphere is warming “quickly” Rate of change IPCC 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 pronounced 5) 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 warming Global warming versus Global climate change--- what is the difference? Do NOT confuse it with ozone depletion

14 New Terminologies 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 earth’s climate.

15 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

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 sources Tourism loss Any good impacts?

19 Projecting Future Changes in Earth’s Climate
Climate models Apparent influence of human activities Could be natural changes

20 Climate models Scientists have developed complex mathematical models of the earth’s climate system. Inputs: Solar energy Earth’s land Ice Greenhouse gases Clouds, winds, water vapor


22 Natural and human emissions
Troposphere Cooling from increase CO2 removal by plants and soil organisms CO2 emissions from land cleaning, fires, and decay Warming from decrease Aerosols Heat and CO2 removal Heat and CO2 emissions Greenhouse gases Ice and snow cover Shallow ocean Land and soil Long-term storage Natural and human emissions Deep ocean

23 IPCC Reports “Best Science”
IPCC (Intergovernmental Panel on Climate Change) 1990, 1995, 2001 and now 2007 reports Three Major Finding From 2001 1) 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 Stream Deep 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 a positive feedback? negative feedback?

29 Cloud Cover Day versus Night Impacts Thick clouds versus thin clouds
High clouds versus Low clouds Latent heat release during cloud formation

30 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

31 Some Possible Effects of a Warmer World

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; and actions 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
Options Do nothing Do more research Act now to reduce risks Precautionary principle

36 What can be done? Improve energy efficiency Reduce fossil fuel use
Renewable energy sources Reduce population growth Reduce deforestation Carbon sequestration


38 Removing CO2 from the Atmosphere
Coal power plant Tanker delivers CO2 from plant to rig Oil 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 Removing CO2 from the Atmosphere

39 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

40 Figure Page 483

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 sunburn Increase in eye cataracts Increased incidence of skin cancer Immune system suppression Increase in acid deposition Lower 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 tetrachloride Methyl chloroform Hydrogen chloride

46 Former Uses of CFCs Air Conditioners Refrigerators Spray cans
Cleaners for electronic parts Sterilizing medical instruments Fumigants 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.

50 Squamous Cell Carcinoma
Melanoma Squamous Cell Carcinoma Basal Cell Carcinoma

51 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

52 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

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.

Download ppt "G. Tyler Miller’s Living in the Environment Chapter 18"

Similar presentations

Ads by Google