Module 1: Global Climate Change and the Greenhouse effect

Global change includes global climate change and global warming

• Global change
  • Change that occurs in the chemical, biological, and physical properties of the planet
  • Fluctuated over the years
  • In recent years, the rates of global change have been much higher
    • Many events have cascading effects
• Global Climate Change
  • Changes in the average weather that occurs in an area over a period of years or decades
  • Can be natural or anthropogenic
• Global Warming
  • The warming of the oceans, land masses, and atm of earth

Solar radiation and greenhouse

The sun earth heating system

• The ultimate source of almost all energy on earth is the sun
• As earth warms, it emits back heat into the atm
• The sun gives out light in form of high energy radiation and visible light
• Earth reflects back this energy in form of infrared waves or heat
• A lot of the UV radiation is absorbed by the ozone layer, some is reflected back into space from reflective surfaces such as clouds, rest is absorbed by earth resulting in earth heating up.
• When earth re-emits energy back into space, some gases can absorb this energy and reflect it back onto earth, heating it even more
  • Greenhouse effect
    • Absorption of infrared radiation by atmospheric gases and reradiation of the energy back towards earth.
• Over long periods of time, this system is fairly stable, however in short time spans, outputs and inputs of energy may be very different.

The gases that cause the greenhouse effect

• N2 and O2 are not greenhouse gases
• H2O is the most common house gas (water vapor)
• GHGs
  • H2O
  • CO2
  • CH4
  • N2O
  • O3
  • CFCs
• O3
  • Ozone is beneficial in stratosphere, but not troposphere
• Greenhouse warming potential
  • An estimate of how much a molecule of any compound can contribute to global warming over a period of 100 years relative to a molecule of CO2