Climate Change

• International Panel on Climate Change (IPCC), concluded human pollutants are to blame for global climate change (2006)
• How the Warming Occurs

  1. The sun produces a range of radiation (UV, Visible and IR)

  2. Most wavelengths are let through the atmosphere and strike the surface of the earth

  3. When high energy UV wavelengths hit the earth’s surface, they convert to lower energy wavelengths (IR)

  4. Infra Red wavelengths give off heat instead of light and are trapped by the atmosphere
• Greenhouse effect

  A natural process that leads to a warmer Earth (it would be 33oC cooler without it), beneficial for life on this planet
• Greenhouse Gases

  • CFCs
  • CH4
  • NO2
  • CO2
• Order of abundance of Greenhouse Gases

  • CO2
  • CH4
  • NO2
  • CFCs
• Burning 1 gallon of gas puts 5.5 pounds of CO2 in the air
• Change in atmospheric gas concentrations since industrial revolution (pre-industrial values): Carbon Dioxide: 280ppm-380ppm, Methane: 714ppb-1740ppb, Nitrous Oxide: 270-319ppb (Source: IPCC 2006 report)
• A melting of the ice caps will decrease the albedo of the earth


  This will be a positive feedback to global warming
• Glacial thaw


  Land-based ice caps will melt, fresh water into ocean (Atlantic Gulf Stream)
• Thermal expansion of water


  Water expands when it heats up
• Seas are projected to rise up to ONE meter in the next 100 years, affecting agricultural areas & cities at sea level
• The oceans absorb CO2, leading to ocean acidification
• Projected Temp Changes

  1. Mean surface temperature should increase .1- .16oC per decade for the next 50 years (IPCC, 2006)

  2. Northern hemisphere should heat up more than Southern hemisphere
• Developed Vs Developing Nations

  Developed nations produce most greenhouse gases (70-75%), impacts will be felt by developing nations
• International agreements to deal with climate change: Limit warming to 2 degrees above pre-industrial levels, preserve carbon sinks (forests), aid developing countries in efforts, mitigate damage caused by climate change $$
• Previous sections of the course covered local air pollution problems such as photochemical smog impacting urban areas like LA
• Previous sections of the course covered regional air quality issues like acid deposition affecting regions where coal burning is common
• This section of the course will cover global atmospheric issues similar to discussions of Ozone depletion
• The International Panel on Climate Change (IPCC) is tasked with digesting current scientific information related to global climate change
• The IPCC has concluded that the current observed warming of the climate is anthropogenic
• Human emissions of greenhouse gases are driving the atmospheric change
• The IPCC has recommended dramatic reductions in global greenhouse gas emissions to slow the warming process
• All countries except the U.S. have signed onto the Paris Climate Accord to reduce greenhouse gases and slow climate change
• The Greenhouse Effect is the process by which the earth traps heat from the sun
• Solar energy from the sun is in the form of visible and UV light, which passes through the atmosphere
• When visible light hits the earth's surface, it is converted to heat energy (infrared radiation IR)
• Greenhouse gases in the atmosphere trap heat energy, not allowing it to easily escape
• Greenhouse gases include carbon dioxide CO2, Methane CH4, nitrogen dioxide NO2, and halons like CFC’s
• Water vapor (H2O) is the main greenhouse gas but is not anthropogenic
• Greenhouse gas concentrations in the atmosphere fluctuate seasonally but remain relatively constant over geological time
• Increasing greenhouse gas concentrations lead to warming periods, while decreasing concentrations lead to ice ages
• Climate changes resulting from changes in greenhouse gas concentrations occur over thousands of years
• Water vapor and aerosols like SO2 reflect sunlight back into space and act as agents of global cooling
• Without water vapor and aerosols, the earth would be much warmer
• Spheres change the earth’s climate on a global scale

  Global impact
• Ice ages and warming periods are a natural part of living on earth
• Anthropogenic climate change is different from natural occurrences due to the time factor
• Discussion on "Air Bubbles in Ancient Ice" presents evidence for anthropogenic climate change
• Since the industrial revolution, humans have been burning fossil fuels as their main energy source
• Concentrations of greenhouse gases in the atmosphere have increased in an extremely short period of time