Global Climate Change

Global Climate Change

1. Definitions

   • Climate: An area's long-term atmospheric conditions (Temperature, moisture, wind, precipitation)
   • Weather: Short term conditions at localized sites
   • Global climate change: Describes trends and variations in Earth's climate ( Temperature, precipitation, storm frequency)
   • Greenhouse gases: Atmospheric gases that absorb infrared radiation (Water, vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons (chlorofluorocarbons [CFCs])
     • Greenhouse gases re-emit infrared radiation, losing some energy to space
     • Greenhouse effect: Phenomenon in which energy travels downward, warming the atmosphere and the planet's surface.
       • Global warming potential: The relative ability of one molecule of a greenhouse gas to contribute to warming
       • Temperature changes have been greatest in the Arctic
         • Average surface temperatures on Earth have increased 0.9c (1.6F) in the past 100 years
   • Paleoclimate: Climate of the geological past
   • Proxy indicators: Indirect evidence that serve as substitutes for direct measurements
     • Cores in sediment beds preserve pollen grains and other plant remnants
       • Three rings include age, preoccupation, droughts, and fires
   • Storm surge: the temporary and localized rise in sea level from high tides and winds from storms
     • 53% of people in the United States live in coastal areas
   • Mitigation: strategy of pursuing actions that reduce greenhouse gas emissions to lessen severity of future climate change
   • Adaptation: Strategy of cushioning ourselves from the impacts of climate change

2. Global warming:An increase in Earth's average temperature

3. Causes

   • Climate change and global warming refer to current trends
     • Precipitation has increased worldwide by 2% over the last century
     • As oceans water warms, it expands in volume
     • Wet areas will get wetter; dry areas will get drier
     • Climate change threatens coral reefs
       • Warmer waters contribute to coral bleaching, which kills corals.
       • Increased CO2 leads to ocean acidification
         • Oceans have already decreased by 0.1 pH unit
   • Three factors influence climate
     • The sun
       • The sun supplies most of the planet's energy
         • The absorbed energy powers winds, waves ,evaporation & photosynthesis
     • the atmosphere
       • The atmosphere and water absorb about 70% of the incoming solar radiation (and reflect 30% into space
         • As Earth's surface absorbs solar radiation, the surface increases in solar radiation and emits infrared radiation
     • the oceans
   • Carbon dioxide is not the most potent greenhouse gas it is however it is present in the largest concentration
     • Deforestation contributes to rising atmospheric CO2

4. Effects

   • Global warming modifies temperature-dependent phenomena
     • Plants bloom earlier in the spring Insects emerge earlier Birds are migrating and animals are breeding earlier
   • 20-30% of species will be threatened with extinction
   • Climate change affects society
     • warmer temperatures and more CO2 may initially boost crop yields
       • But more warming will lead to shortened growing sessions, decreased production, crops being more suspectible to droughts,
     • Forestry increased fires, invasive species
     • Economics: Costs will outweigh benefits of climate change
       • External costs of damages will be $10-350/ton of carbon

5. Who or What is To Blame?

   • Scientists agree that increased greenhouse gases are causing global warming