Global Warming Ch. 13

Introduction Is the world getting warmer? If so, are the actions of mankind to blame for earth’s temperature increases? What can/should be done about these issues? Are the potential resolutions worth the cost to implement them?

History of Earth’s Climate Photosynthesis began billion years ago  Produced oxygen and removed carbon dioxide and methane (greenhouse gases)  Earth went through periods of cooling (“Snowball Earth”) and warming Earth began cycles of glacial and interglacial periods ~3 million years ago

Sun Earth’s Temperature Solar Energy Solar Energy Radiative Cooling Radiative Cooling

Sun Earth’s Temperature Solar Energy Solar Energy Radiative Cooling Radiative Cooling

Factors that determine climate Many factors affect it:  1.) Latitude  2.) circulation patterns  3.) local geography  4.) solar activity  5.) volcanic activity

Continued… 1.) Latitude:  Low latitudes equal dark and light  High latitudes are seasonal on light

Continued… 2.) Atmospheric Circulation:  Wind is formed based on Earth’s heat  This influences weather patterns  (Equator = lots of rain)  Wind patterns establish an areas weather  Prevailing Winds (30-60)

Continued… 3.) Oceanic Circulation Patterns:  Great affect on climate  Hold large amounts of heat  El Nino: (WARM PHASE)  Short-term change in location of warm and cold water masses in Pacific Ocean  Lots of moisture in Southern USA and SA  Drought in Australia  La Nina:  Opposite of El Nino (COLD PHASE)

El Nino and La Nina

Main Ocean Currents Adapted from IPCC SYR Figure 4-2

Continued… 4.) Topography:  Mountains and Mt. Ranges affect precipitation patterns  Creates Rain Shadow (dry side of Mt.)

Continued… 5.) Other causes:  Volcanic Activity:  Sulfur dioxide reacts with dust to cause haze  Blocks sunlight  Solar Activity:  Solar maximum: high amounts of UV released  Creates more ozone  Warms stratosphere

13-2: The Ozone Shield Area where ozone is highly concentrated Absorbs UVA and UVB Ozone is made of 3 oxygen atoms

Chemicals that are bad CFC’s (Chlorofluorocarbons)  Thought to be miracle chemical  Non-poisonous  Non-corrosive  No smell  Stable at Earth’s surface  Contains 4 chlorine molecules  These can destroy 100,000 ozone molecules

Process of Ozone Destruction

Ozone Hole: 1985:  Hole over South Pole  Ozone thinned by %  Occurred during the spring 1997:  Arctic North of Canada also showed signs of weakening  45 % below normal

Effects on Humans UV light is dangerous to living things  It destroys DNA and causes mutations  Ex.) Skin Cancer Damaging Effects:  Interferes with Photosynthesis  Kills phytoplankton  Premature aging of skin

Protecting ozone 1987: Montreal Protocol  Nations agreed to sharply cut CFC’s  Used replacement CFC’s  Don’t hurt ozone However CFC’s remain active for years

Ch. 13-3: Global Warming Greenhouse Effect:  When gases and absorb and radiate heat  Major Gases:  Water Vapor  Carbon Dioxide  CFC’s  Methane  Nitrous Oxide

Measuring Carbon Dioxide Measure in ppm’s  Devised by Keeling in the 50’s  Noticed CO2 decreased in summer/ increased in winter  Why? Over 50 yrs of measurement  CO2 increased ( )  ~17 % increase

How certain is Global Warming Scientific community believes increase in global gases = warmer temps  Global Warming However they are not sure how much impact humans are having on it  Cannot accurately model global warming

Ice Sheets Melting? GRACE and Zwally  found melting of Antarctica ice sheet melting  Zwally also concluded Greenland is melting  Why does it matter? Results in rising sea levels

Wildlife Effects Polar Bears  Require pack ice to live  Might eventually go extinct in the wild Sea turtles  Breed on the same islands as their birth  Could go extinct on some islands as beaches are flooded Other species may go extinct as rainfall patterns change throughout the world Polar Bears  Require pack ice to live  Might eventually go extinct in the wild Sea turtles  Breed on the same islands as their birth  Could go extinct on some islands as beaches are flooded Other species may go extinct as rainfall patterns change throughout the world

Effect on Humans & Weather Fewer deaths from cold, more from heat Decreased thermohaline circulation  Cooler temperatures in North Atlantic Precipitation changes  Droughts and famine (some areas)  Expanded arable land in Canada, Soviet Union  More severe storms

Reducing the Risk Kyoto Protocol:  Adopted in 1997  Cut CO 2 emissions by 5% from 1990 levels for  USA refused to sign it

Mitigation of Global Warming Conservation  Reduce energy needs  Recycling Alternate energy sources  Nuclear  Wind  Geothermal  Hydroelectric  Solar  Fusion?