Global Climate Change

Scientific Evidence

1. Global Temperature Regulation: certain molecules regulate our atmosphere

• greenhouse gases: absorb infrared energy and heat up atmosphere (CO2, N2O, and CH4)

Greenhouse Effect: different wavelengths of light are absorbed by greenhouse gases, the surface, and some is reflected

• the more greenhouse gases present in atmosphere the more heat is trapped

• reflected energy can be absorbed as well

2. Human Activities

Effect on Greenhouse concentration: activities have dramatically increased the concentration of gases in the atmosphere

• increase of CO2 through energy production, reduction of CO2 regulators, erosion and weathering

  • combustion

  • removal of trees, pollution of oceans (less cover, phytoplankton, regulators)

  • increased erosion releases CO2

Measuring Ancient Greenhouse Gases

1. Ice Cores: track the amount of CO2, N2O, Ch3 in the pre-historic past

   • CH4 retains the most energy but has the lowest concentration, we focus mostly on CO2/N2O

   • drill into ice sheet, pull up long cylinder of ice

   • observe layers: annual layers and ash layer indicate time

   • bubbles contain gases

   • past to 100,00 in the past

2. Other records: fossils of corals, plants, geology, and glaciers

   • out issue is the rate

Signs of Climate Change

1. Changes in plant hardiness zones: in USA hardiness zones are shifting north

2. Arctic Sea-Ice: floating ice that goes through annual cycles

   • measure the location and volume of boundaries

   • last 15 years, there has been a consistent reduction

   • summer ice could be gone by 2050 (influences geopolitics)

3. Ice mass Reduction: melting arctic ice doesn’t increase seal level, but melting ice from landmass (antartica) increases sea level

   • Arctic Ice: 4 year freeze/thaw cycle

   • Albedo: how reflective an object is 0-1, glacial Ice= 0.5-0.7, fresh snow= 0.9, average ocean= 0.06

     • melting of arctic ice means less albedo and more energy absorbed into the oceans, and the same time cold water is increased which impact warm currents and climate

IPCC: Intergovernmental Panel on Climate Change,