G. Tyler Miller’sLiving in the Environment
Chapter 18
G. Tyler Miller’sLiving in the Environment
Chapter 18
Climate Change and Ozone Loss
Key ConceptsKey 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
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.
Past Climate ChangesPast Climate Changes
• 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.
Past Climate ChangesPast Climate Changes
Past globaltemperatures
Past globaltemperatures
Recent trends in global temperatures
Recent trends in global temperatures
Today’s global average temp 59oF, 15oC
The Earth’s Natural Greenhouse Effect 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 190-210 ppm
What is the Greenhouse EffectWhat is the Greenhouse Effect
Fig: 6-14
Table 21-1Page 464
Table 21-1Page 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
15–390
65
42
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
Air conditioners, refrigerators, plastic foams
Air conditioners, refrigerators, plastic foams
Fire extinguishers
Cleaning solvent
Relative Warming Potential (compared to CO2)
1
23
296
900–8,300
470–2,000
130–12,700
5,500
1,400
Climate Change and Human Activities 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 160,00years.
U.S. and Greenhouse GasesU.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
Is the troposphere warming?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
Is the troposphere warming?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.
Is the troposphere warming?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 TerminologiesNew 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.
Factors Affecting the Earth’s TemperatureFactors Affecting the Earth’s Temperature
Changes in solar output
Changes in Earth’s 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 GlaciersWarning 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 GlaciersWarning Signals From GlaciersMount 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 Earth’s Climate
Projecting Future Changes in Earth’s Climate
Climate models
Apparent influence of human activities
Apparent influence of human activities
Could be natural changes
Climate modelsClimate modelsScientists have
developed complex mathematical models of the earth’s climate system.
Inputs:• Solar energy• Earth’s land • Ice• Greenhouse gases• Clouds, winds, water
vapor
Troposphere
Aerosols
Greenhousegases
Warmingfromdecrease
Cooling from increase
CO2 removal by plants and soil organisms
CO2 emissions from land cleaning, fires, and decay
Heat andCO2 removal
Heat andCO2 emissions
Ice and snow cover
Natural and human emissions
Land and soil
Shallow ocean
Long-termstorage
Deep ocean
IPCC Reports “Best Science”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
IPCC Reports “Best Science”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
Ocean Storage of CO2 and HeatOcean 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.
Ocean Storage of CO2 and HeatOcean Storage of CO2 and HeatEvidence 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 CO2 and HeatOcean Storage of CO2 and Heat
Oceans also act to trap about 29% of CO2 released into the atmosphere as part of global carbon cycle.
Cloud CoverCloud 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 CoverCloud 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 AtmospherePossible 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
Some Possible Effects of a Warmer World
Some Possible Effects of a Warmer World
Solutions: Dealing with the ThreatSolutions: Dealing with the ThreatScientists 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.
Dealing with the Threat of Climate Change
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
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 ThreatSolutions: Dealing with the Threat
Options
Do nothing
Do more research
Act now to reduce risks
Precautionary principle
What can be done?What can be done?
• Improve energy efficiency
• Reduce fossil fuel use
• Renewable energy sources
• Reduce population growth
• Reduce deforestation• Carbon sequestration
Treeplantation
Coalpower plant
Tanker deliversCO2 from plantto rig
Oil rig
Crop fieldSwitchgrass
Spent oil reservoir isused for CO2 deposit
CO2 is pumpeddown to reservoir through abandoned oil field
Abandonedoil field
CO2 ispumped downfrom rig for deepocean disposal
= CO2 deposit
= CO2 pumping
Removing CO2 from the Atmosphere
Reducing CO2 Emissions
What Can You Do?
• 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
Figure 21-20Page 483
Figure 21-20Page 483
What is Being Done to Reduce Greenhouse Gas Emissions?
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.
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.
Loss of the Ozone Layer: Reasons for ConcernLoss 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 levelLong-lived chemicals and ozone level1. The first chlorofluorocarbon (CFC) was discovered in 1930. 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 ChemicalsOzone Depleting Chemicals
Chlorofluorocarbons (CFCs)Halons(used in fire extinguishers)Methyl bromide (dry cleaning)
Carbon tetrachlorideMethyl chloroformHydrogen chloride
Former Uses of CFCsFormer Uses of CFCs
• Air Conditioners• Refrigerators• Spray cans• Cleaners for electronic parts• Sterilizing medical instruments• Fumigants for granaries and cargo ships
Seasonal Ozone Layer Thinning at the PolesSeasonal 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.
• 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.
• Increased UV radiation reaching the earth’s surface from ozone depletion is harmful to human health, crops, forests, animals, and materials. Figure 21-24 lists the effects of ozone depletion.
• Exposure to UV radiation is a major cause of skin cancers.
• Caucasians are most susceptible to melanomas.
Basal Cell Carcinoma
Melanoma
Squamous Cell Carcinoma
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 LayerSolutions: Protecting the Ozone LayerCFC substitutes Montreal Protocol : 1987; 35 nations to cut CFC by
35% in 2000Copenhagen Protocol: phase out of all
ozone depleting chemicals
Protecting the Ozone LayerProtecting 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.