Unit 9: Global Change - Climate Change and Biodiversity

Stratospheric ozone is considered the "good" ozone (O3). It absorbs high-energy UV radiation in the atmosphere.
UV radiation can cause sunburn, skin cancer, and eye damage; sunblock helps protect against these effects.
Ozone forms when UV radiation strikes oxygen molecules (O2), splitting them into single oxygen atoms (O).
- These oxygen atoms react with O2 to form ozone (O3).

Ozone depletion was discovered in 1985 with the finding of a "hole" (thinning) in the ozone layer over the Antarctic Pole.
This thinning occurs seasonally due to man-made chemicals from the halogen family, including chlorine, fluorine, and bromine.
Chlorine is the primary concern in ozone depletion because it's a major component of chlorofluorocarbons (CFCs).
- CFCs are found in aerosols, refrigerants, and manufacturing processes.
- Their use has been reduced due to the Montreal Protocol.
UV radiation causes CFCs to decompose, releasing chlorine, which reacts with ozone (O3) to form chlorine monoxide (ClO).
- $CFC + UV \rightarrow Cl$
- $Cl + O_3 \rightarrow ClO$
Chlorine monoxide then reacts with other ozone molecules, breaking them down into Cl and two oxygen molecules (O2).
- $ClO + O3 \rightarrow Cl + 2O2$
- This process depletes the ozone layer.

The Montreal Protocol was created in the 1980s to phase out CFCs and replace them with other chemicals like hydrofluorocarbons (HFCs).
- HFCs don't cause ozone depletion but are strong greenhouse gases.
Protecting the ozone layer helps protect humans, animals, and other organisms from sunburn, skin damage, skin cancer, and eye damage such as cataracts.

The greenhouse effect is a naturally occurring process that keeps the planet warm.
Heat from the sun (infrared) enters the atmosphere and is reflected back out to space; greenhouse gases trap some of this heat, warming the surface.
Too many greenhouse gases intensify heat trapping, leading to a warming trend.
Greenhouse gases primarily originate from human activities (anthropogenic), mainly fossil fuel combustion, which produces carbon dioxide (CO2).
The Kyoto Protocol is an agreement to reduce greenhouse gases worldwide, recognizing that most are produced by humans.

Common greenhouse gases include:
- Water vapor
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
- CFCs
Warming potential refers to how much heat a gas can trap; the higher the potential, the more heat is trapped.
- Carbon dioxide has a warming potential of 1, serving as the baseline.
- Methane has a significantly stronger warming potential than carbon dioxide.
- Nitrous oxide and CFCs have much stronger warming potentials than methane.
Time in the atmosphere also affects warming; the longer a gas lasts, the greater its effect.
Water vapor has a relatively short time in the atmosphere due to the hydrologic cycle.

Global warming results from increased greenhouse gases, causing changes in climate.
Carbon dioxide levels vary seasonally due to plant productivity, but overall show an upward trend.
- Plants take in more CO2 during productive times, causing a zigzag drop in CO2 levels.
- During dormant times, plants take in less CO2, causing the line to go back up.
The increase in CO2 correlates to human use of fossil fuels and net destruction of vegetation.
Global temperatures show a constant increase, though not evenly across the planet.

Extreme northern latitudes (North Pole) experience temperature changes from 1 to 4 degrees Celsius.

Increasing temperatures cause thawing of tundra permafrost (permanently frozen ground).
Thawing releases methane (CH4), a strong greenhouse gas, encouraging further warming.
This cycle continues, with more thawing leading to more methane release and further warming.

Loss of habitat (e.g., ice melting affecting polar bears).
Species moving into different locations as biomes shift north and south.
Diseases spreading further north and south due to species like mosquitoes moving.
Soil productivity changes.
Ocean and wind currents shifting.
Increases in ice melting, raising sea level.
Thermal expansion of the ocean, where water particles move faster and expand as they warm.

Ocean warming occurs as the Earth's surface warms, with greenhouse gases trapping more heat.
Ocean species may experience metabolic and reproductive changes.
Coral bleaching occurs as algae leaves coral due to warming oceans, causing coral to turn white.
Ocean acidification occurs as the ocean absorbs carbon dioxide (CO2).
- $CO2 + H2O \rightarrow H2CO3$ (carbonic acid).
Carbonic acid steals carbonate from organisms that need it to build shells.

Biodiversity is affected by human actions; HIPPO is a way to remember the major factors: H.I.P.P.C.O
- Habitat destruction (including fragmentation).
- Invasive species.
- Population growth of humans.
- Pollution (air and water pollution).
- Climate change.
- Overexploitation of species.
Factors in HIPPO can lead to threatened and endangered species.
The Endangered Species Act in the United States helps protect these species.
Threatened and endangered species are at high risk of extinction.
Factors leading to species becoming threatened and endangered include overexploitation, being specialists, outcompetition by invasive species, and specific habitat requirements.

Endangered Species Act protects species from habitat loss and harm.
CITES Trade Agreement helps countries regulate the trade of animals and plants to ensure trade doesn't harm populations.