Wind scale

Global warming - increased surface temperature due to natural and man-made causes. But……what’s the problem? Questions: 1) What is the problem?: Increased atmospheric temperature. 2) What are the effects?: The effects are numerous. Rising sea level, more frequent and larger floods, shifting climate regions, biology. 3) Natural or man-made?: Both. 4) Should something be done? If so, what? Why? At what cost?

Methods: 1) Examine the processes and cycles involved. 2) Records of past climates and climate changes. 3) Measuring past and present day human activities: industrialization. Conclusions: You decide.

Factors that affect global climate: Fluctuations in solar energy - 11-year sunspot cycle Earth Orbital variations - distance from sun, angle of tilt 10,000-400,000 year cycles Albedo - reflectivity of earth and atmosphere clouds, ice, water, land, and plants Factors that affect local climate: Heat islands caused by cement and asphalt in cities. Smog

Heat island

The Greenhouse Effect: gases in the troposphere absorb and re-radiate infrared radiation (heat). This warms the troposphere and makes the earth habitable. Greenhouse gases: CO2 Carbon Dioxide H2O Water vapor CH4 Methane N2O Nitrous Oxide O3 Ozone

The Greenhouse Effect - it’s natural!

The problem is: Enhanced Greenhouse Effect. Causes: Increased concentration of greenhouse gases. i.e. CO2 Decreased concentrations of ozone in the stratosphere. First: What are the paths of carbon on the earth?

Carbon Cycle - without humans Short time scale Long time scale Medium time scale

Long term cycling of Carbon due to volcanism and metamorphism From Our Changing Planet, Mackenzie, 1997

Human input: ~1.0%/year At this rate, CO2 would double in 70 years!

Mauna Loa Observations Current CO2 concentration: ~360 ppm Anthropogenic CO2 ? Past CO2 concentration: ice core From Our Changing Planet, Mackenzie, 1997

Sources of methane: Decay of organic material in rice paddies, swamps, termite guts, oil and coal production, continental shelf. Earth Science, Tarbuck & Lutgens, 2000

Vostok ice core record CO2 Temperature Methane From Our Changing Planet, Mackenzie, 1997

Putting off the next glaciation for 1000 years? Future effects: Putting off the next glaciation for 1000 years? From Our Changing Planet, Mackenzie, 1997

Effects of global warming? Sea level rises. Earth Science, Tarbuck & Lutgens, 2000

Future effects: Rising temperatures? From Our Changing Planet, Mackenzie, 1997

Ozone and the Antarctic ozone hole: Ozone protects us from harmful UV solar radiation Ozone is created and destroyed naturally in the stratosphere. However, anthropogenic chemical compounds, such as: CFC-11, CFC-12 chlorofluorocarbons (amongst many others!) act as a catalyst in the depletion of ozone.

From Our Changing Planet, Mackenzie, 1997

Chlorine or Bromine or Nitrogen Ingredients: Chlorine or Bromine or Nitrogen UV solar radiation From Our Changing Planet, Mackenzie, 1997

Other ingredients: Polar stratospheric clouds - generated in the austral winter Polar vortex -

Mt. Pinatubo

Ozone movie From Our Changing Planet, Mackenzie, 1997