Ch. 3 - Global Climate Changes

Greenhouse gases have natural sources

• Evaporation and evapotranspiration (H2O)

• Volcanic eruptions (CO2 in ash cloud)

• Denitrification: convert nitrate to N2O

  • Chemical reaction by bacteria in wet, anaerobic environments (wet soils)

• Combustion from natural wildfires

• Decomposition

• Digestion

Greenhouse gases have human sources

• Deforestation

• Landfills

• Burning fossil fuels

• Agricultural practice

• Industrial production of new chemicals

CFCs global warming potential is ___ because it can stay in the atmosphere

great

Greatest greenhouse gas contributor

carbon dioxide

Greenhouse gas standardization

converting other gases to equivalent amount of CO2 that would cause same warming effect

CO2 concentration fluctuates _____, overall is increasing

seasonally

Sawtooth pattern

CO2 concentration decreases spring and summer, increases in winter (lack photosynthesis)

Isolated air in ice cores tell us

past atmospheric conditions

• ice layers melt —> trapped air released

• Gas composition is determined

Greenhouse gas accumulation _____ water temperature

increases

• Ocean absorbs 90% excess heat from climate change —> earth would be warmer

Long term changes in earth climate

• Increased storm intensity

• Altered patterns of ocean circulation

• Melting ice sheets and glaciers

Melting ice reflects ____ solar energy into atmosphere, ________ global temperature

less, increasing

Ground surface

uppermost layer: exposed to seasonal temp variation

Active layer

thaws in summer, freezes in winter

Permafrost

permanently frozen ground layer (soil), remains below freezing

Unfrozen ground

Beneath permafrost, remains above freezing due to geothermal heat

Permafrost thaws —>

dead, organic material can now decompose (produces CH4)

Rising sea levels

• Coastal flooding

• Habitat loss

• Salinity change

• Erosion and deposition

Increased evaporation

• More water in atmosphere = intense storms

• More evaporation = dry land surface, drought