APES Unit 9 | AP Exam Review

Troposphere

• Ozone (O₃) from photochemical smog; harmful

• Greenhouse gases/greenhouse effect

Ozone Layer

Naturally-occurring ozone (O₃) that provides protection from UVB-UVC rays

Stratospheric Ozone

UVA - 5% absorbed

UVB - 95% absorbed

UVC - 100% absorbed

UVB

• UV light in the 240-315 nm will disrupt the bond of the ozone molecule & convert this ozone back to oxygen

• Peak ozone destruction occurs at 254 nm wavelength of UV light

UVC

• UV light below 240 nm will disturb the bond of the oxygen molecule & form 2 oxygen atoms

• These oxygen atoms will quickly attach to natural oxygen to form ozone

• Peak ozone generation occurs at 185 nm wavelength of UV light

Antarctic Spring

1. Antarctic winters can create stratospheric clouds of ice crystals

2. Crystals melt in the beginning of the spring

3. Chemical reactions convert less reactive chlorine to a more reactive form

4. Chlorine degrades ozone into atmospheric oxygen (O₂)

5. The ozone layer thins

Chlorofluorocarbons (CFCs)

• Refrigerant/coolant

• Propellant

• Some types of plastics

Effects of Ozone Depletion

• Thinning of ozone layers, especially at poles

• Disruption of terrestrial photosynthesis

• Disruption of photosynthesis by phytoplankton

• Disruption of food chains/webs

• Impacts populations of some organisms like amphibians

• Impacts human health: Skin cancer, cataracts

Montreal Protocol

A landmark international treaty, adopted in 1987, that aims to protect the ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS)

Antarctic Ozone

Seasonal thinning of the ozone layer that occurs over Antarctica each spring, primarily due to the presence of chlorine and bromine from ozone-depleting substances & unique meteorological conditions

HCFCs

Hydroflourocarbons

• No chlorine to catalyze transformation of ozone into atmospheric oxygen

• Powerful greenhouse gas

Greenhouse Effect (Keeps Earth Warm)

• Some energy is reflected, some energy is re-radiated as heat back into space

• Some re-radiated heat is absorbed by greenhouse gases in the troposphere, then emitted again toward the surface of the Earth as heat

• Helps keep the Earth at a temp that can support life

Greenhouse Gases

• Carbon Dioxide - CO₂

• Methane - CH₄

• Water vapor - H₂O

• Nitrous oxide - N₂O

• Chloroflourocarbons (CFCs) - CF₂Cl₂

• Hydroflourocarbons (HCFCs)

• Tropospheric ozone - O₃

Carbon Dioxide Emissions

Transportation - 34%

Electricity - 32%

Industry - 15%

Residential & Commercial - 11%

Other (Non-Fossil Fuel Combustion) - 7%

Methane Emissions

Enteric Fermentation - 28%

Natural Gas & Petroleum Systems - 28%

Landfills - 17%

Manure Management - 10%

Other - 9%

Coal Mining - 8%

Nitrous Oxide Emissions

Agricultural Soil Management - 78%

Stationary Combustion - 7%

Industry or Chemical Production - 6%

Manure Management - 4%

Transportation - 4%

Other - 2%

Global Greenhouse Gas Emissions by Economic Sector

Electricity & Heat Production - 25%

Agriculture, Forestry, & Other Land Use - 24%

Industry - 21%

Transportation - 14%

Other Energy - 10%

Buildings - 6%

Global Warming Potentials (GWP)

Carbon Dioxide - 1 [standard]

Methane - 20

Nitrous Oxide - 300

Ozone - 900-1000

CFCs - 4,600 - 10,000

HFCs - 150 - 12,000

Sea Levels Rise

• Land ice (ie. continental glaciers, ice sheets) melts, adding to the volume of water in the ocean

• Thermal expansion of the ocean, due to warming from climate change, increases the volume of the ocean

Climate Change Impacts Populations

1. Habitat destruction

2. Loss of food source

3. Timing of food source availability changes

4. New temperatures beyond range of tolerance

5. New salinity beyond range of tolerance

6. Increased storm intensity

7. Increased possibility of fire

8. Impacted annual group behaviors: Timing of migration, hibernation

Populations Impacted by Climate Change

• Low-income populations

• Occupational groups

• People in certain locations

• Pregnant women

• People w/ pre-existing medical conditions

• Children

• Older adults

• People w/ disabilities

• Indigenous people

Rising Temperatures Melt Global Ice

• Melting polar ice reveals darker soil & water (lower albedo than ice), which drives a positive feedback warming loop

• Melting permafrost releases methane gas, which drives a positive feedback warming loop

• Melting sea ice affects species that depend on the ice for habitat & food, such as polar bears & seals

Causes of Ocean Warming

Ocean warming is the global increase in ocean water temps

• Amount of warming isn't uniform across the globe--some ocean areas have warmed ore quickly than others

Ocean warming is caused by increased greenhouse gases in Earth's atmosphere (ie. carbon dioxide & methane)

• IPCC estimates that our oceans have absorbed 93% of the excess heat from greenhouse gas emissions since the 1970s

Effects of Ocean Warming

Increases in GHG emissions can lead to a variety of environmental problems

• Rising sea levels from:

  • Melting ice sheets

  • Ocean water expansion

Thermal expansion of the ocean due to ocean warming causes

• Rising sea levels

• Displacement of coastal populations due to flooding

Ocean Warming Effects Marine Species

• Loss of habitat

• Metabolic changes

• Reproductive changes

• Coral bleaching

Loss of Habitat (Ocean Warming Effects Marine Species)

• Reduction of sea ice negatively impacts hunting/feeding patterns

• Higher water temps impact predator/prey interactions, as prey migrate to cooler areas

• Sea level rise alters coastlines, impacting species that use both land & water resources

• Rising coastal seas may push some communities out of the photic zone

• Warming oceans may impact primary productivity of phytoplankton, which are the basis of marine food webs

Metabolic Changes (Ocean Warming Effects Marine Species)

• As the ocean warms, marine species may migrate, but can't locally escape to cooler areas -- They're always surrounded by the warmer water

• Organisms are pushed to their biological thermal limits & become weakened or die

• Reduction of biodiversity/disruption of trophic structures

Reproductive Changes (Ocean Warming Effects Marine Species)

• Organisms weakened by thermal stress don't reproduce well

• Many marine reproductive patterns (mating times, egg hatching times, larval development) are timed based on specific ocean temps -- Disruption of these temp patterns leads to reproductive harm

Coral Bleaching (Ocean Warming Effects Marine Species)

• Corals have algae that live within their bodies in mutualistic relationship: Besides helping provide food for the coral, these algae also give corals their unique colors

• Warming ocean temps stress the corals

• When stressed, corals expel their symbiotic algae, which give them a "bleached" appearance

• Corals CAN recover from a bleaching event, but, if the conditions that caused the bleaching continue, this will often lead to the death of the coral

Problems of Coral Bleaching

• Coral colonies are the foundation of highly biodiverse reef ecosystems

• The loss of coral colonies means that there will be a loss of habitat for the other species that depend on them

• This loss will also disrupt the trophic structure of the reef ecosystem

• Degraded reefs are vulnerable to invasive species, which have the potential to create permanent negative ecosystem impacts

Ocean Acidification

Decrease in pH of ocean waters

Contributions to Ocean Acidification

Anthropogenic Activities (that lead to increased CO₂)

• Burning/combustion of fossil fuels

• Vehicle emissions

• Deforestation