Chapter 21 Global Climate Change

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Chapter 21Global Climate Change
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Overview of Chapter 21

• Introduction to Climate Change
• Atmosphere and Weather
• Causes of Global Climate Change
• Effects of Climate Change
• Melting Ice and Rising Sea Level
• Changes in Precipitation Patterns
• Effects on Organisms
• Effects on Human Health
• Effects on Agriculture
• Dealing with Global Climate Change

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Atmosphere Structure
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Atmospheric Structure

• Troposphere
• Lowest layer
• Densest layer
• Temperature decreases with altitude
• Contains most of the water vapor and weather
• Stratosphere
• Second layer
• Much less dense than troposphere
• Temperature increases with altitude

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Atmospheric Structure

• Mesosphere
• Coldest layer
• Temperature increases with altitude
• Thermosphere
• Hottest layer
• Temperature increases with altitude
• Exosphere
• Beyond Earths atmosphere merges with
  interplanetary gases

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• Atmospheric Concentrations (Constant)

Constituent Formula Concentration (ppm)
Nitrogen N2 780,840 Oxygen
O2 209,460 Argon
Ar 9340 Neon
Ne 18.18 Helium
He 5.24 Krypton Kr 1.14
Hydrogen H2 .50 Xenon Xe .09
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Atmospheric Concentrations (Variable)

• Constituent Formula Conc. ppm
• Water Vapor H20 .1 30,000
• Carbon Dioxide CO2 350
• Methane CH4 1.67
• Nitrous Oxide N2O .30
• Carbon Monoxide CO .19
• Ozone O3 .04
• Ammonia NH3 .004
• Nitrogen Dioxide NO2 .001
• Sulfur Dioxide SO2 .001
• Nitric Oxide NO .0005
• Hydrogen Sulfide H2S .00005

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History of Earth Climate
http//vathena.arc.nasa.gov/curric/land/global/cli
mchng.html
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• Milankovitch Cycles time periods of oscillations

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Introduction to Climate Change-Mean Annual
Global Temperature 1960-2005
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How Do We Know About Past Climate?

• The geological record of carved mountain valleys,
  scratched bedrock, and glacial debris and
  moraines
• Recently, cores have been removed from the ice at
  Vostok Station in Antarctica.
• The longest cores are about 2000 meters, sampling
  layers of ice deposited as early as 160,000 years
  ago. The ice trapped bubbles of air when it
  froze. The ratio of oxygen isotopes in this air
  indicates the average air temperature at the time
  the bubble was trapped in ice. The bubbles also
  trap atmospheric greenhouse gases that can be
  measured.

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How Do We Know?

• Fossil plants and the distribution of pollen show
  that vegetation has changed, consistent with
  changing climate.
• Pollen from plants, buried in shallow deposits of
  earth, indicate the distribution of vegetation
  since the last glaciations, about 20,000 years
  ago.
• Ancient Plant Distribution describes how
  vegetation has changed as the ice retreated

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How Do We Know?

• The historical record speaks to us for some 2,000
  years and there have been real quantitative
  measurements since about 1850.

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Oceans and Atmosphere

• Oceans Importance
• Role in hydrologic cycle
• Regulation of heat and moisture
• Ocean currents move heat as well as water
• Oceanic physical and biogeochemical processes are
  major regulators of natural atmospheric carbon
  dioxide
• High specific heat of water heats and cools
  slooowly

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Oceans and Atmosphere

• 2. The Oceanic Conveyor System
• A global system that continually exchanges
  water, heat, and salt among all of the oceans and
  between the surface layer and the deep waters

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• The exchange of heat between the ocean and
  atmopshere, as estimated from an inverse model
  (units are in W/m2). Red numbers are regions
  where the ocean undergoes net heating, and blue
  numbers indicate areas where there is net cooling
  ( indicates standard errors of the estimates)
  areas are bounded by observations along the lines
  shown. The model combines oceanic dynamics with
  global hydrographic data base. Macdonald,
  MIT-WHOI PhD Thesis, 1995

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Climate Change Terminology

• Greenhouse Gas
• Gas that absorbs infrared radiation
• Ex Carbon dioxide, methane, nitrous oxide,
  chlorofluorocarbons and tropospheric ozone
• Positive Feedback
• Change in some condition triggers a response that
  intensifies the changed condition
• Infrared Radiation
• Radiation that has a wavelength that is longer
  than that of visible light, but shorter than that
  of radio waves
• Greenhouse Effect
• Increase of heat in a system where energy enters
  (often as light), is absorbed as heat, and
  released sometime later

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Introduction to Climate Change

• Evidence for Climate Change
• 11 of the 12 years between 1995 and 2006 were
  among the twelve warmest years since the
  mid-1800s
• Phenological spring in N. hemisphere now comes 6
  days earlier
• Warming is not due to natural causes
• Human produced greenhouse gases are most
  plausible explanation

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Causes of Climate Change

• Greenhouse gas concentrations increasing

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Causes of Climate Change

• Increased concentration of CO2 (right)
• Burning fossil fuels in cars, industry and homes
• Deforestation
• Burning of forests

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Greenhouse Effect
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Greenhouse Effect
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Greenhouse Animation

• http//epa.gov/climatechange/kids/global_warming_v
  ersion2.html

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Greenhouse Gases

• Carbon Dioxide CO2
• Causes of increased atmospheric CO2
• Combustion of fossil fuels
• Deforestation
• Removal of other vegetation

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Greenhouse Gases CO2

• Review of carbon cycle
• C in CO2 in atmosphere and in water is moved to
  glucose by photosynthesis
• C in glucose is moved to CO2 by cell respiration
• C in glucose is moved to organic molecules by
  synthesis reactions in living things
• C in organic molecules in organisms is moved to
  fossil fuels over millions of years
• C in limestone (CaCO3) is released slowly to CO2
  when exposed to oxygen or water

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Greenhouse Gases CO2

• Largest reservoir of carbon sedimentary rocks
  (limestone)
• Second largest reservoir of carbon top 300m of
  ocean (dissolved CO2), living things in ocean

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Greenhouse Gases

• Water Vapor H2O
• Methane CH4
• Sources fermentation, swamp gas, livestock,
  natural gas production, coal mining, landfill
  emissions, manure
• Nitrous Oxide N2O
• Sources agriculture, combustion of biomass,
  combustion of fossil fuels, anaerobic
  denitrificaiton, acts as a greenhouse gas and
  contributes to ozone depletion

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Greenhouse Gases

• CFCs (anthropoenic)
• CFC chlorofluorocarbon (hydrocarbon halogenated
  specifically with Cl or F)
• 10,000 times more efficient than CO2 in absorbing
  IR radiation
• Uses refrigerants, industrial solvents, fire
  suppressants

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Other Pollutants Cool the Atmosphere

• Atmospheric Aerosols tend to cool the atmosphere
• Both human and natural sources
• Tiny particles that remain in troposphere for
  weeks or months
• Contain many chemicals, but often contain sulfur
• Complicates models of climate change

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Climate Models

• Climate affected by
• winds, clouds, ocean currents, and albedo
• Used to explore past climate events
• Advanced models can project future warming events
• Models are only as good as the data and law used
  to program them
• They have limitations

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Climate Models
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Effects of Global Climate Change

• Ocean as CO2 sink - excess CO2 is starting to
  harm ocean life

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Effects of Global Climate Change- Melting Ice and
Rising Sea Levels

• Sea level rise caused in 2 ways
• Thermal Expansion
• Water expands as it warms
• Melting of land ice
• Retreat of glacier and thinning of ice at the
  poles
• Melting has positive feedback
• Increased melting decreases ice, which decreases
  albedo leading to further warming

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• C\Documents and Settings\kmajka-johnston\My
  Documents\APES\climate change\methane.htm

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Melting Ice and Rising Sea Levels
1957
1998
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Case-In-Point Impacts in Fragile Areas

• Eskimo Inuit live traditional life dictated by
  freezing climate
• Climate change is altering their existence
• Wildlife are smaller or displaced
• Reduced snow cover and shorter river ice seasons
• Thawing of permafrost (right)

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Effects of Global Climate Change- Changing
Precipitation Patterns

• Some areas will get more water, some areas will
  have greater droughts
• Ex Hurricanes will likely get stronger

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Effects of Global Climate Change- Effects on
Organisms

• Zooplankton in parts of California Current have
  decreased by 80 since 1951
• Effecting entire food chain
• Decline in krill around Antarctica
• Caused decrease in penguin populations
• Species have shifted their geographic range
• Migrating birds are returning to summer homes
  earlier
• Food is not available at this time

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Effects on Organisms - Coral Reefs

• Coral reefs can be bleached (right) due to
  increase in water temperature
• Affects coral symbiotes and makes them more
  susceptible to diseases to which they would
  otherwise be immune

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Effect on Organisms - VegetationBeech Tree Range
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Effects on Human Health

• Increased number of heat-related illnesses and
  deaths

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Effects on Agriculture

• Difficult to anticipate
• Productivity will increase in some areas and
  decrease in others
• Rise in sea level will inundate flood plains and
  river valleys (lush farmland)
• Effect on pests is unknown
• Warmer temperatures will decrease soil moisture-
  requiring more irrigation
• Location (i.e. elevation and altitude) where
  certain crops can be grown may have to change

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International Implicationsof Climate Change

• Developed vs. Developing countries
• Differing self-interests
• Differing ability to meet the challenges of
  climate change

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Dealing with Global Climate Change

• To avoid the worst of climate change, CO2 levels
  must be stabilized at 550ppm
• 50 higher than current levels
• Two ways to attempt to manage climate change
• Mitigation
• Focuses on limiting greenhouse gas emissions to
  moderate global climate change
• Adaptation
• Focuses on learning to live with to the
  environmental changes and societal consequences
  brought about by global climate change

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Dealing with Global Climate Change- Relationship
Between Mitigation and Adaptation
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Dealing with Global Climate Change- Mitigation

• Locate/invent alternative fuels to fossil fuels
• Increase efficiency of cars and trucks
• Sequestering carbon before it is emitted
• Plant and Maintain trees to naturally sequester
  carbon

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Dealing with Global Climate Change- Adaptation

• Rising sea levels and coastal populations
• Move inland
• Construct dikes and levees
• Adapt to shifting agricultural zones
• NYC sewer line

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International Efforts to Reduce Greenhouse Gas
Emission

• Kyoto Protocol
• Legally binding
• Provides operational rules on reducing greenhouse
  gases
• US and Australia have not sign it- it will be
  difficult to implement without US backing