Unit 9 Review: Global Change, Climate Change, and Biodiversity

Stratospheric ozone is beneficial, absorbing high-energy UV radiation.
UV radiation can cause sunburn, skin cancer, and eye damage.
Ozone (O3) forms when UV radiation strikes oxygen molecules (O2), splitting them into single oxygen atoms.
These single oxygen atoms react with O2 to form O3.

Ozone depletion is a serious climate change issue.
In 1985, a large "hole" or thinning in the ozone layer was discovered over Antarctica.
This thinning is seasonal and caused by anthropogenic (human-made) chemicals.
Halogens like chlorine, fluorine, and bromine are the chemicals involved.
Chlorine is the primary damaging component of chlorofluorocarbons (CFCs).
CFCs were found in aerosols, refrigerants, and manufacturing processes but have been phased out due to the Montreal Protocol.
UV radiation causes CFCs to decompose, releasing chlorine, which reacts with ozone (O3) to form chlorine monoxide (ClO).
Chlorine monoxide reacts with other ozone molecules, breaking them down into Cl and two oxygen molecules (O2).

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

The greenhouse effect is a naturally occurring process that keeps the planet warm.
Heat from the sun (infrared radiation) enters Earth's atmosphere and some is reflected back into space.
Greenhouse gases trap some of this heat, warming the planet and making it habitable.
Too many greenhouse gases can intensify heat trapping, leading to global warming.
Greenhouse gases primarily originate from human causes, such as fossil fuel combustion, which produces carbon dioxide (CO2).

The Kyoto Protocol addresses the greenhouse effect.
It is an agreement to reduce greenhouse gases worldwide, recognizing that most are human-produced.

Greenhouse Gas	Warming Potential	Time in Atmosphere	Source
Water Vapor	Low	Relatively Low	Cycles through the hydrologic cycle.
Carbon Dioxide	1	Varies	The baseline for measuring other gases. Produced through fossil fuel combustion.
Methane	Significantly Stronger than CO2	Varies
Nitrous Oxide	Much Stronger than CO2	Varies
CFCs	Much Stronger than CO2	Varies	Retain large amounts of heat. Phased out under the Montreal Protocol but persist in the atmosphere.

Global warming is a result of increased greenhouse gases.
Climate is not changing uniformly across the planet.
CO2 levels vary seasonally due to plant productivity, but overall show an upward trend.
Atmospheric CO2 increase correlates with human use of fossil fuels and net destruction of vegetation.
Global temperatures show a constant increase, though not evenly distributed worldwide.
Extreme northern latitudes (e.g., North Pole) are experiencing temperature changes of 1-4 degrees Celsius.

Positive feedback loops encourage further warming.
Thawing Tundra Permafrost:
- Increasing temperatures cause thawing of tundra permafrost (permanently frozen ground).
- Thawing releases methane, a strong greenhouse gas, into the atmosphere.
- Increased methane encourages further warming and thaw, creating a cycle.
Melting Ice and Snow:
- Ice and snow have a high albedo (reflectivity), reflecting heat back into space.
- As ice and snow melt, more water is exposed in polar oceans.
- Water has a lower albedo and absorbs more heat from the sun.
- Increased absorption leads to more ice melting and higher temperatures.

Loss of habitat (e.g., ice melting affecting polar bear hunting grounds).
Species moving into different locations as biomes shift.
Diseases spreading further north and south due to species like mosquitoes expanding their range.
Soil productivity changes.
Shifting ocean and wind currents.
Increased ice melting, raising sea levels.
Thermal expansion of the ocean: Water particles become more energetic and move faster as they warm, increasing ocean volume.

Ocean warming occurs as the Earth's surface warms due to trapped heat from greenhouse gases.
Water has a high heat capacity and absorbs heat, increasing ocean temperatures.

Ocean species may experience metabolic and reproductive changes (similar to thermal pollution).
Coral bleaching occurs due to the warming of the oceans.
- Algae living in coral leaves and dies, causing the coral to turn white.

The ocean absorbs carbon dioxide (CO2) from the atmosphere.
CO2 mixes with ocean water (H2O) to form carbonic acid (H2CO3):
$CO2 + H2O ightharpoonup H2CO3$
High levels of carbonic acid make the ocean more acidic over time.
Carbonic acid steals carbonate from organisms that need it to build their shells, hindering their growth.

Endangered Species Act (United States): Protects species from losing habitat and from further harm.
CITES trade agreement (International): Regulates the trade of animals and plants to ensure trade is not detrimental to populations.

Strong legislation to protect species (e.g., Endangered Species Act).
Criminalizing poaching.
Protecting the habitat of species.
Installing habitat corridors to allow species to travel between fragmented areas.
Reintroduction programs (e.g., gray wolves in Yellowstone National Park).
Monitoring land use to make it more sustainable.
Breeding programs (often done in zoos).
Restoring compromised ecosystems and lost habitats.
Reducing non-native and invasive species.