Climate Control and Ozone Depletion

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Climate Control and Ozone Depletion

• Chapter 19

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19-1 How Might the Earths Temperature and
Climate Change in the Future?

• Concept 19-1 The overwhelming scientific
  consensus is that the earths atmosphere is
  warming rapidly, mostly because of human
  activities, and that this will lead to
  significant climate change during this century.

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Global Warming and Global Cooling Are Not New

• 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

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Estimated Changes in the Average Global
Temperature of the Atmosphere

• Over the past 900,000 years, the troposphere has
  experienced prolonged periods of global cooling
  and global warming.
• Since the end of the last ice age a little more
  than 10,000 yrs ago, the temperature has been
  relatively stable.

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Estimated Changes in the Average Global
Temperature of the Atmosphere

• For the past 1,000 years temperatures have
  remained fairly stable but began to rise during
  the last century.
• This increase coincides with the beginning of the
  industrial revolution, large scale deforestation,
  and the widespread use of fossil fuels.

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Estimated Changes in the Average Global
Temperature of the Atmosphere

• A record of CO2 measurements taken at the top of
  Mauna Loa volcano in Hawaii since 1958.
• Commonly known as the Keeling Curve after
  Charles David Keeling who supervised the
  measurements

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Estimated Changes in the Average Global
Temperature of the Atmosphere
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Estimated Changes in the Average Global
Temperature of the Atmosphere
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How Do We Estimate Past Temperature Changes?

• Scientists can estimate the changes in Earths
  past by analyzing
• Direct temperature measurements since 1861
• Tree rings
• Pollen from the bottom of deep lakes/bogs
• Bat dung deposited in caves over 1000s of yrs.
• Ocean floor sediments
• Radioiostopes in rocks and fossils
• Past glaciation formations
• Air bubbles in ancient glaciers

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

• Scientists analyze the gas isotopes found in tiny
  air bubbles trapped in ice cores to learn about
  past
• troposphere composition
• temperature trends
• greenhouse gas concentrations
• solar activity
• snowfall amounts
• forest fire activity

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Our Climate, Lives, and Economies Depend on the
Natural Greenhouse Effect

• Three major factors shape the earths climate
• The sun
• The Oceans store CO2 and heat, evaporate and
  receive water, move stored heat to other parts of
  the world
• The Greenhouse effect that warms the earths
  lower troposphere and surface because of the
  presence of greenhouse gases

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Our Climate, Lives, and Economies Depend on the
Natural Greenhouse Effect

• The Earths average temp is 57º F (14º C)
• Without the natural greenhouse effect the average
  temp. would be -2º F (-19º C)

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Our Climate, Lives, and Economies Depend on the
Natural Greenhouse Effect

• The major atmospheric greenhouse gases are
• Water Vapor (H2O) the most abundant greenhouse
  gas, warmer air holds more water vapor (positive
  feedback)
• Carbon Dioxide (CO2) enters the atmosphere
  through the burning of fossil fuels, solid waste,
  trees and wood products, etc. It is removed from
  the atmosphere or sequestered when it is
  absorbed by plants as part of the carbon cycle.
• Methane (CH4) emitted during the production and
  transport of fossil fuels, from livestock and
  other agricultural practices, and by the decay of
  organic waste in municipal solid waste landfills.
• Nitrous Oxide (N2O) emitted during agricultural
  and industrial activities and during combustion
  of fossil fuels and solid waste.

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Atmospheric Levels of CO2 and CH4, Global
Temperatures, and Sea Levels
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Human Activities Emit Large Quantities of
Greenhouses Gases

• Since the Industrial Revolution (1860-2004)
• Average concentrations of CO2, CH4, and N2O
  emissions are much higher
• Mostly due to burning of fossil fuels,
  agriculture, and deforestation

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Human Activities Emit Large Quantities of
Greenhouses Gases

• Countries with the largest CO2 emissions
• United States (25)
• China (5)
• European Union (27 countries)

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The Atmosphere Is Warming Mostly Because of Human
Activities

• In 1988, the UN established the Intergovernmental
  Panel on Climate Change (IPCC).
• It includes more than 2,500 climate scientists in
  more than 130 countries.
• Its 2007 report indicated a 9099 likelihood
  that the lower atmosphere is warming AND that
  human activity is responsible for most of the
  recent warming.
• Evidence that supports the major conclusions of
  the IPCC
• The 20th century was the hottest in the past 1000
  yrs.
• 19062005 Ave. tropospheric temp increased about
  0.74C
• 19702005 Annual greenhouse emissions up 70
• Past 50 years Arctic temp rising almost twice as
  fast as the rest of the earth

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The Atmosphere Is Warming Mostly Because of Human
Activities

• Evidence that supports the major conclusions of
  the IPCC
• Glaciers and floating ice sheets are melting and
  shrinking at increasing rates
• Prolonged droughts increasing
• During the last century, sea level rose by 10-20
  cm, mostly due to runoff from melting and
  land-based ice and the expansion of ocean water
  as temperatures rise.
• Warmer temps. in Alaska, Russia, and the Arctic
  are melting permafrost releasing more CH4 into
  the troposphere.
• The range and distribution of plants and animals
  is shifting towards the poles.
• In the mid-latitudes, spring is coming earlier
  and fall is coming later.

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The Atmosphere Is Warming Mostly Because of Human
Activities
May 30, 1868
May 30, 2005
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Feedback Loops Positive and Negative

• Some factors can amplify (positive feedback) and
  some can dampen (negative feedback) projected
  global warming

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Is a Hotter Sun the Culprit?

• Is a hotter sun the culprit? No.
• Since 1975, the troposphere has warmed while the
  stratosphere has cooled.
• A hotter sun would cause the entire atmos. to
  warm

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Can the Oceans Save Us?

• The oceans can absorb large amounts of CO2
• 25-30 of man-made CO2 is absorbed by the ocean
• Some is converted into carbonate salts that sink
  to bottom
• Some is used by marine plants
• Problems
• The warmer water is, the less CO2 it can hold
• As the oceans warm, more CO2 will have to stay in
  the atmosphere and warm the planet even more
• Positive feedback loop
• CO2 levels increase ocean acidity
• Also decreases CO2 solubility in ocean water
• Effect on coral reefs dissolves the calcium
  carbonate

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There Is Uncertainty about the Effects of Cloud
Cover on Global Warming

• Warmer temperatures create more clouds that could
  shade and cool the troposphere, but water vapor
  is also a greenhouse gas.
• 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 contrails on climate temperature?

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Outdoor Air Pollution Can Temporarily Slow
Global Warming

• Aerosol and particulate pollutants produced by
  human activities can cool the atmosphere through
  a process called global dimming. The high
  amounts of pollutants can actually help to shade
  the planet.
• Ironically, global warming will accelerate as
  particulate and SO2 pollution is reduced.
• Creates a cooling effect that may have partially
  masked the effects of global warming
• This is why we have seen a slightly lower
  global temp. increase than
  some
  climate models predicted.

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What Is the Scientific Consensus about Future
Temperature Change?

• Mathematical models used for predictions
• They represent simplified models of major
  processes that interact to determine the average
  temperature and greenhouse gas content of the
  troposphere.
• Most models show
• Global warming will continue to occur at a rapid
  rate
• Human factors are the major cause of temperature
  rise since 1950
• Human activities will play an ever increasing
  role in the warming trend during the next century

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Simplified Model of Some Major Processes That
Interact to Determine Climate
Troposphere
Ice and snow cover
Shallow ocean
Land and soil biotoa
Natural and human emissions
Deep ocean
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Core Case Study Studying a Volcano to
Understand Climate Change

• NASA scientists correctly predicted that the 1991
  eruption of Mount Pinatubo in the Philippines
  would cool the average temperature of the earth
  by 0.5o C over a 15 month period and then return
  to normal by 1995.

• Particulates and SO2 were the main reasons for
  the temp. decrease.
• The success convinced scientists and policy
  makers that climate model projections should be
  taken seriously.

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Comparison of Measured Temperature from 18602007
and Projected Changes
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19-2 What Are Some Possible Effects of a Warmer
Atmosphere?

• Concept 19-2 The projected rapid change in the
  atmosphere's temperature during this century is
  very likely to increase drought and flooding,
  shift areas where food can be grown, raise sea
  levels, result in intense heat waves, and cause
  the premature extinction of many species.

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19-2 What Are Some Possible Effects of a Warmer
Atmosphere?

• Important distinction
• Global Warming vs. Climate Change
• Global warming the temperature of the
  troposphere increasing as a result of an increase
  in the natural greenhouse effect
• Climate change a broader term referring to any
  changes in the Earths climate as a result of a
  warmer troposphere

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19-2 What Are Some Possible Effects of a Warmer
Atmosphere?

• Remember we are not talking about local weather,
  we are talking about global climate.
• A rapid increase in the temperature of the
  troposphere during this century would give us
  little time to deal with its harmful effects.
• Many scientists fear a tipping point after
  which rapid/severe climate changes cannot be
  prevented.
• Plant/animal distribution and ocean/atmosphere
  circulations are based on the current global
  climate.
• What if the climate changes??

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Severe Drought Is Increasing The Browning of
the Earth

• Drought accelerates global warming, leads to more
  droughts
• Severe lack of water
• Growth of trees and other plants will slow
• Less CO2 taken out of atmosphere
• Also, more forest and grass fires will add CO2 to
  the atmosphere
• Groundwater, lakes, and rivers will be depleted
  because of lack of precip., increased
  evaporation, and increased need to agricultural
  irrigation.

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Ice and Snow Are Melting

• Why will global warming be worse in the polar
  regions?
• Because the ice was reflecting 90 of the
  sunlight back into spacewhen it melts it is
  replaced by water which absorbs 90 of the
  sunlight.
• Positive feedback loop

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Ice and Snow Are Melting
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Ice and Snow Are Melting

• The worlds sea ice sheets and land-based
  glaciers are slowly melting.
• The loss of ice is happening much faster than
  scientists thought possible.
• Why should we care if snow and ice are melting?
• Arctic ice regulates the temperature and
  precipitation of regions to the south (North
  America, Europe)
• Mountain glaciers play a vital role in the water
  cycle and the availability of fresh water for
  hundreds of millions of people.
• Drinking
• Agriculture

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Ice and Snow Are Melting
2004
1948
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Sea Levels Are Rising

• Average sea level has been slowly rising and the
  rate is increasing

• 2/3 of the rise is the from the thermal expansion
  of warm water
• The remaining 1/3 of the rise is from the melting
  of land-based ice
• Floating ice is already in the water (buoyancy)

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Sea Levels Are Rising

• 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
  (groundwater)
• Submergence of low-lying islands in the Pacific
  and Indian Oceans and the Caribbean

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Areas of Florida to flood if average sea level
rises by one meter
Sea Levels Are Rising

• 13 of the worlds urban population lives near
  sea level
• Many cities would be devastated by even
  relatively small increases in sea level

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Permafrost Is Likely to Melt Another Dangerous
Scenario

• As arctic temperature increases, permafrost melts
  and the organic matter in soils and lake bottoms
  decomposes, releasing CH4
• Effect on global warming
• Warmer air can release methane gas stored in
  bogs, wetlands, and tundra soils and accelerate
  global warming.

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Ocean Currents Are Changing but the Threat Is
Unknown

• Ocean currents act like large conveyor belts
  redistributing heat all over the planet.
• Global warming can change ocean currents by
  increasing the temp. of the water, adding large
  amounts of freshwater from melting ice, and
  increasing salinity by increasing evaporation.

• The temp. of water greatly effects the temp. of
  the air above it.

• Many areas have warmer climates despite their
  higher latitudes that will change if the ocean
  currents change

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Extreme Weather Will Increase in Some Areas

• By altering ocean currents and air circulation,
  global warming can both excessive warming or
  cooling.
• This will lead to prolonged heat waves and
  droughts in some areas and prolonged heavy rains
  and increased flooding in other areas.
• Hurricanes and typhoons feed off the warm ocean
  waters. If these waters are warmer, that means
  more energy for the storms and stronger storms.

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Global Warming Is a Major Threat to Biodiversity

• Habitat loss and ecosystem changes will cause
  many species to seek new habitats or face
  extinction.
• Specialist species that cannot evolve or migrate
  fast enough are the most vulnerable.
• An estimated 30 of land plants/animals could go
  extinct with only a 2ºC temp. increase

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Changes in Average Ocean Temperatures, Relative
to Coral Bleaching Threshold
Global Warming Is a Major Threat to Biodiversity

• Most susceptible ecosystems
• Coral reefs, polar seas, coastal wetlands, alpine
  and arctic tundra

Exploding Populations of Mountain Pine Beetles in
British Columbia, Canada
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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
• However, it will be less productive soil not as
  fertile
• Loss of productivity could be offset by a longer
  growing season

• Genetically engineered crops developed to be more
  tolerant to drought and temperature extremes

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Climate Change Will Threaten the Health of Many
People

• Global warming will increase human deaths from
• Heat stroke
• Increased flooding
• Malnutrition and starvation from disruption of
  food supply
• Spread of tropical diseases to temperate regions
• More insects, microbes, toxic molds, and fungi
• Increase in some forms of air pollution, more O3
• Decreased amount of vital natural capital
• Increased number of environmental refugees
• Increased poverty

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19-3 What Can We Do to Slow Climate Change?

• Concept 19-3A To slow the rate of global warming
  and climate change, we can increase energy
  efficiency, sharply reduce greenhouse gas
  emissions, rely more on renewable energy
  resources, and slow population growth.
• Concept 19-3B Governments can subsidize energy
  efficiency and renewable energy use, tax
  greenhouse gas emissions, set up cap-and-trade
  emission reduction systems, and help to slow
  population growth.

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Dealing with Climate Change Is Difficult

• Climate change is such a difficult problem to
  deal with because
• The problem is global
• The effects will last a long time
• It is a long-term political issue
• The harmful and beneficial impacts of climate
  change are not spread evenly
• Many actions that might reduce the threat are
  controversial because they can impact economies
  and lifestyles

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What Are Our Options?

• Mitigation the act of decreasing or reducing
  something
• Taking actions aimed at reducing the extent of
  global warming by reducing the production of
  greenhouse gases or their emission into the
  atmosphere
• We can improve energy efficiency, rely more on
  carbon-free renewable energy resources, and find
  ways to keep much of the CO2 we produce out of
  the troposphere.
• Adaptation change along with the changing
  climate
• We recognize that some warming is unavoidable and
  devise strategies to reduce its harmful effects,
  or live with the outcome.

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Solutions Global Warming, Methods for Slowing
Atmospheric Warming
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Case StudyIs Capturing and Storing CO2 the
Answer?

• Carbon sequestration - removing CO2 from the
  atmosphere and storing it

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Ways to Prepare for the Possible Long-Term
Harmful Effects of Climate Change
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Governments Can Help Reduce the Threat of
Climate Change

• A program to slow and adapt to global warming now
  is very likely to cost less than waiting and
  having to deal with its harmful effects later.
• Governments can tax greenhouse gas emissions and
  energy use, increase subsidies and tax breaks for
  saving energy, and decrease subsidies and tax
  breaks for fossil fuels.
• Getting countries to agree on reducing their
  greenhouse emissions is difficult.

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The Kyoto ProtocolInternational Climate
Negotiations

• In 1997, delegates from 161 countries met in
  Kyoto, Japan to negotiate a treaty on global
  warming which went into effect January, 2005.
• It requires 38 participating developed countries
  to cut their emissions of CO2, CH4, and N2O to
  5.2 below their 1990 levels by 2012.
• This represents a reduction of 2010 levels by 29
• The protocol implements a cap-and-trade program
  that involves setting a cap or limit on
  emissions.
• If a country emits less than their allowed limit,
  they can sell the remaining allowances to another
  country.
• Many countries distribute their allowance to
  specific companies or power plants.
• Developing countries were excluded.

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The Kyoto ProtocolInternational Climate
Negotiations

• 191 countries have signed and ratified the
  protocol.
• U.S. signed the protocol but has not ratified it.
• Developing countries such as China, India and
  Brazil were considered exempt
• Belief that it would hurt the U.S. economy
• The U.S. did not sign, but 10 U.S. states and 740
  U.S. Cities are participating.
• The Kyoto Protocol will have little effect on
  global warming without support and action by the
  U.S., China, and India.

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Some Are Reducing Their Carbon Footprints

• What is your carbon footprint?
• The impact you have of the Earth (in terms of CO2
  emissions) through your actions, decisions, and
  purchases.
• Carbon neutral a balance between the amount of
  carbon released into the atmosphere and the
  amount sequestered or removed from the atmosphere

• U.S. cities, states, businesses, and schools are
  taking initiatives to reduce carbon emissions