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9.1 D.V.1
- The stratospheric ozone layer is important to the evolution of life on Earth and the continued health and survival of life on Earth
- Stratospheric ozone depletion is caused by anthropogenic factors, such as chlorofluorocarbons and natural factors, such as melting of ice crystals in the atmosphere at the beginning of the Antarctic spring.
- A decrease in stratospheric ozone releases the UV rays that reach the Earths surface. Exposure to UV rays can lead to skin cancer and cataracts in humans

9.1 D.V.2
- CFCs break down stratospheric ozone
1. CFCs were used as refrigerants, coolants, propellants, components of plastics
2. CFCs can escape and enter the stratosphere
3. UV light removes chlorine from CFCs
4. Free chlorine catalyzes the conversion of O3 to O2

9.1 D.V.3
- Effects of ozone depletion
1. Thinning of ozone layers, especially at poles
2. Disruption of terrestrial photosynthesis
3. Disruption of photosynthesis by phytoplankton
4. Disruption of food chains/webs
5. Impacts populations of some organisms like amphibians
6. Impacts human health: skin cancer, cataracts

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9.2 D.V.1
- Ozone depletion can be mitigated by replacing ozone-depleting chemicals with substitutes that do not deplete the ozone layer. Hydrofluorocarbons (HFCs) are one such replacement, but some are strong greenhouse gases.

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9.3 D.V.1
- The principal greenhouse gasses are carbon dioxide, methane, water vapor, nitrous oxide, and chlorofluorocarbons (CFCs)
- While water vapor is a greenhouse gas, it does not contribute significantly to global climate change because it has a short residence time in the atmosphere
- The greenhouse effect results in the surface temperature necessary for life on Earth to exist
- Carbon dioxide, which has a global warming potential of 1, used as a reference point for the comparison of different greenhouse gases and their impacts on global climate change. CFCs have the highest GWP, followed by nitrous oxide, then methane

9.3 D.V.2
- Tropospheric gases create the greenhouse effect
1. Greenhouse gases include carbon dioxide, methane nitrous oxide, water vapor, tropospheric ozone, CFCs, HFCs.
2. Most occur naturally, but concentrations are increased via anthropogenic means.
3. CFCs and HFCs are manmade.
4. Water vapor does not contribute significantly to the greenhouse effect, due to its short atmospheric residence time.

9.3 D.V. 3
- Greenhouse gases have different impacts on the greenhouse effect
1. Carbon dioxide is a reference molecule for the greenhouse effect, so has a global warming potential of 1.
2. GWPs of various greenhouse gases: CFCs/HFCs> ozone>nitrous oxide>methane>carbon dioxide
3. Carbon dioxide has the greatest overall impact on the greenhouse effect because of its concentration in the atmosphere.
4. Human activities influence the concentration of various greenhouse gases in the atmosphere

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TOPIC 4 INCREASES IN THE GREENHOUSE GASES

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TOPIC 4 INCREASES IN THE GREENHOUSE GASES

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9.4 D.V.1
- Global climate change, caused by excess greenhouse gases in the atmosphere, can lead to a variety of environmental problems, including rising sea levels resulting from melting ice sheets, ocean water expansion, and disease vectors spreading from the tropic to the poles. These problems can lead to changes in population dynamics and population movements in response.

9.4 D.V.2
Climate impacts: Increased temperatures, precipitation extremes, extreme weather events, sea level rise
Exposure: Extreme heat, poor air quality, reduced food and water quality, changes in infectious agents, population displacement
Health outcomes: Heat-related illness, cardiopulmonary illness, food water and vector-borne disease, mental health consequences
Environmental and institutional context: land-use change, infrastructure condition, ecosystem change, agricultural production and livestock use
Social and behavioral context: age and behavior, race and ethnicity, poverty, housing and infrastructure, education, discrimination, preexisting health conditions, access to care and community health infrastructure

9.4 D.V. 3
Climate change has global impacts:
- environmental- changes in ocean salinity and temperature affect marine organisms at every trophic level in many ways...affect terrestrial organisms at every trophic level
- humans- responses to temperature changes, access to foos, access to fresh water, and changing land availability
- drives climate change- activities are individual actions, agriculture, industry

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9.5 D.V. 1
- The Earth has undergone climate change throughout geologic time, with major shifts in global temperatures causing periods of warming and cooling as recorded with CO2 data and ice cores
- Effects of climate change include rising temperatures, melting permafrost and sea ice, rising sea levels, and displacement of costal populations.
- Winds generated by atmospheric circulation help transport heat throughout the Earth. Climate may change circulation patterns, as temperature changes may impact Hadley cells and the jet stream.
- Climate change can affect soil through changes in temperature and rainfall, which can impact soil's viability and potentially increase erosion.

9.5 D.V. 2
- Earth's polar regions are showing faster response times to global change because ice and snow in these regions reflect the most energy back out to space, leading to a positive feedback loop.
- As the Earth warms, this ice and snow melts, meaning less solar energy is radiated back into space and instead is absorbed by the Earth's surface. This in turn causes more warming of the polar regions.
- Global climate change response time in the Arctic is due to positive feedback loops involving melting sea ice and thawing tundra, and the subsequent release of greenhouse gases like methane

9.5 D.V. 3
- Marine ecosystems are affected by changes in sea level, some positively, such as in newly created habitats on now-flooded continental shelves, and some negatively, such as deeper communities that may no longer be in the photic zone of seawater
- Oceanic currents, or the ocean conveyer belt, carry heat throughout the world. When these currents change, it can have a big impact on global climate, especially in the costal regions.

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9.6 D.V. 1
- Ocean warming is caused by the increase in greenhouse gases in the atmosphere
- Ocean warming can affect marine species in a variety of ways, including loss of habitat, and metabolic and reproductive changes
- Ocean warming is causing coral bleaching, which occurs when the loss of algae within corals cause the coral to bleach white. Some recover and some die

9.6 D.V. 2
- ocean warming is caused by increased greenhouse gases in Earth's atmosphere
- Oceans absorb heat from the atmosphere, so rising levels of heat-trapping GHGs lead to rising sea levels as the ocean thermally expands
- Rising sea levels can cause the displacement of coastal populations due to flooding
- Ocean warming can also impact marine species via: habitat loss, metabolic changes, reproductive changes

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9.7 D.V. 1
- Ocean acidification is the decrease in pH of the oceans, primarily due to increased CO2 concentration in the atmosphere and can be expressed in chemical equations
- As more CO2 is released into the atmosphere, the oceans, which absorb a large part of that CO2, become more acidic
- Anthropogenic activities that contribute to ocean acidification are those that lead to increased CO2 concentrations in the atmosphere: burning of fossil fuels, vehicle emissions, and deforestation
- Ocean acidification damages coral because acidification makes it difficult form to form shells, due to the loss of calcium carbonate.

9.7 D.V. 2
- Environmental problems that affect marine ecosystems: overfishing, destructive fishing practices, increased ocean temperatures, invasive species, oil spills, garbage and plastic debris/pollution, nutrient pollution/eutrophication, mercury spills
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9.8 D.V. 1
- Invasive species are species that can live, and sometimes thrive, outside their normal habitat. Invasive species can sometimes be beneficial, but they are considered invasive when they threaten native species
- Invasive species are often generalist, r-related species and therefore may outcompete native species for resources.
- Invasive species are controlled through a variety of human interventions

9.8 D.V. 2
- Characteristics: r-relates/generalist, some have excellent dispersal methods, early onset of sexual maturity, frequent reproductive events, superior environmental skills
- often outcompete native species
- are non-native species accidentally or purposefully introduced into an ecosystem that threaten or harm native populations

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9.10 D.V.1
- HIPPCO describes the main factors leading to a decrease in biodiversity
- Habitat fragmentation occurs when large habitats are broken into smaller, isolated areas. Causes of habitat fragmentation include the construction of road and pipelines, clearing for agriculture development, and logging.
- The scale of habitat fragmentation that has an adverse effect on the inhabitant of a given ecosystem will vary from species to species within that ecosystem

9.10 D.V. 2
- Global climate change can cause habitat loss via changes in temperature, precipitation, and seal level rises
- Some Organisms have been somewhat or completely domesticated are now managed for economic returns, such as honeybee colonies and domestic livestock. This domestication can have a negative impact on the biodiversity of that organism.

9.10 D.V. 3
- Some ways humans can mitigate the impact of loss of biodiversity include creating protected areas, use of habitat corridors, promoting sustainable land use practices, and restoring lost habitats

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9.9 D.V. 1
- A variety of factors can lead to a species becoming threatened with extinction, such as being extensively hunted, having a limited diet, being outcompeted by invasive species, or having specific and limited habitat requirements
1. As habitats are lost or altered globally, many species are threatened with extinction
2. Factors such as:

- being extensively hunted

- having a limited diet

- being outcompeted by invasive species

- having specific, limited habitat requirements
- Not all species will be in danger of extinction when exposed to the same changes in their ecosystem. Species that are able to adapt to changes in their environment or that are able to move to a new environment are less likely to face extinction.

- biological and behavior traits will determine the risk of extinction when exposed to change

- adaptation requires genetic diversity

- immigration and migration are key

Hunting:
- Poaching is the illegal hunting, killing, or capturing of animals for sale or profit
- Animals are hunted for: Food, Prized body parts, Traditional medical uses, medical research purposes, Sport

Limited diet and habitat:
- Species who are niche specialists are generally at a greater risk of extinction
- Specialists traits: Specific habitat requirements, Limited diet, Low reproductive rates,long gestation periods, Few offspring with high parental care

- As global change intensifies, ecosystems are at risk and specialist species may be less able to adapt to rapid environmental changes

Competition from invasive species
- Invasive species typically r-selected niche generalists
- Generalists who can tolerate a broad range of abiotic conditions and have a varied diet may outcompete native species with more specific requirements---> increased risk of extinction of native species

9.9 D.V. 2
- Selective pressures are any factors that change the behaviors and fitness of organisms within an environment
- Species in a given ecosystem compete for resources like food, territory, mates and habitat, and this competition may lead to endangerment or extinction

Selective pressures and adaptation:
- Selective pressure is any external factor that changes the behavioral and fitness of organisms within an environment
- Selective pressures determine which genetic/behavioral traits are favorably adapted to the environment
- Selective pressures will change in changing environments (some advantageous traits may not always remain advantageous)

Invasive species and competition:
- Under changing environmental conditions, generalist invasives will have a competitive advantage over specialist natives, and may drive the native species to extinction
- Competition can occur within or between species in an ecosystem where there are limited resources
- Competition consumes important metabolic resources, so competitive strategies generally evolve to limit resource conflicts through resource partitioning
- Organisms may compete within their own species or between species such as, territory, food, mates, habitat
- Although competition is normal, species seek to limit competition because it is biologically costly

9.9 D.V. 3
Strategies to Protect endangered species:
- Legislation (with enforcement) is one primary way to protect endangered species
- Criminalizing poaching and institution steep fines/or punishment for poachers can help
- Laws prohibiting the harming of endangered species and their habitats, or the trade in endangered species: The Lacey Act, the Endangered Species Act, The Marine Mammal Protection Act, CITES

- The establishment of protected areas for species such as wildlife refuges or national parks
- Enforcement of conservation practices within protected habitat areas