Unit 9.1: The Stratospheric Ozone Depletion

• Troposphere VS Stratosphere

  • These are the two locations for ozone in our atmosphere 

  • Troposphere- produces ozone from photochemical smogs, greenhouse gas effect (can be harmful)

  • Stratosphere - naturally occurring ozone that provides protection from UVB-UVC rays

    • Using that radiation to transform ozone (O3) to atmospheric oxygen (O2)

• Antarctic Spring

  • Antarctic winters can create stratospheric clouds full of ice crystals

  • Crystals melt in the beginning of the spring 

  • Chemical reactions convert less reactive chlorine into a more reactive form

  • Chlorine degrades ozone into atmospheric oxygen (O2)

  • The ozone layer thins

• Chlorofluorocarbons (CFCs)

  • Refrigerant/coolant

  • Propellant

  • Some types of plastics

  • CFCs can escape and enter the stratosphere 

  • UV light removes chlorine from CFCs

  • Free chlorine catalyzes the conversion of O3 to O2

• Effects of Ozone Depletion

  • Thinning of ozone layers, especially at poles

  • Disrupts photosynthesis, both terrestrial and in phytoplankton 

  • Disrupts food chains and food webs

  • Impacts populations of some organisms like amphibians 

  • Impacts human health: skin cancer, cataracts

Unit 9.2: Reducing Ozone Depletion 

• Montreal Protocol - an international treaty that phased out the use of CFCs and their manufacture in 1987

  • They did this upon recognizing CFCs were thinning the ozone layers and harming the environment 

  • However CFCs are persistent, so it will take decades for CFCs currently in the stratosphere to completely dissipate, allowing the ozone layer to fully repairable  

• HFCs (hydrofluorocarbons) replace CFCs

  • No chlorine to catalyze transformation of ozone into atmospheric oxygen

  • Powerful greenhouse gas

Unit 9.3: The Greenhouse Effect

• The greenhouse effect occurs in the troposphere 

• The sun’s solar radiation warms the earth

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

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

• The “greenhouse effect” helps to keep the Earth at a temperature that can support life

• The greenhouse effect and the ozone layer are in two separate layers of the atmosphere

• Greenhouse gasses

  • Carbon dioxide - CO2

    • Vast majority come from combustion, either from transportation or fossil fuels

  • Methane - CH4

    • Comes from enteric fermentation, natural gas and petroleum systems, and several other sources 

  • Water vapor - H2O

    • Condenses and produces precipitation, does not spend much time in the atmosphere

    • Does not play a large role in the greenhouse effect

  • Nitrous Oxide - N2O

    • It is an agricultural source management issue

  • Chlorofluorocarbons (CFCs) - example: CF2Cl2

    • Both CFCs and HFCs are man made

  • Hydrofluorocarbons (HFCs)

    • Substitution for CFCs

  • Tropospheric Ozone - O3

    • Comes from photochemical smog

• Carbon dioxide is a reference molecule for the greenhouse effect, so has a global warming potential (GWP) of 1

• GWPs or various greenhouse gasses: CFCs/HFCs > ozone > nitrous oxide > methane > carbon dioxide

• Carbon dioxide has the greatest overall impact on the greenhouse effect because of its concentration in the atmosphere

• Human activities influence the concentration of various greenhouse gasses in the atmosphere

Unit 9.4: Increases in the Greenhouse Gasses

• Greenhouse gasses that produce the greenhouse effect include carbon dioxide, methane, nitrous oxide, ozone, CFCs, HFCs, and water vapor

• Concentrations of many greenhouse gasses have steadily increased in the atmosphere as a result of human activity 

• Increased greenhouse gasses have led to climate change

• Sea Levels Rise

  • Land ice (example: 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

• Disease vectors expand their range 

• Climate change impacts Ecological Populations

  • Habitat destruction 

  • Loss of food source

  • Timing of food source availability changes 

  • New temperatures beyond range of tolerance

  • New salinity beyond range of tolerance 

  • Increased storm intensity 

  • Increased possibility of fire

  • Impacted annual group behaviors timing of migration, hibernation

• Climate Change Impacts Human Populations

  • Low-income populations

  • Occupational groups

  • People in certain locations

  • Pregnant women

  • People with pre-existing medical conditions 

  • Children 

  • Older adults 

  • People with disabilities 

  • Indigenous people

• Climate Change Has Global Impact

  • Environmental Impacts

    • Changes in ocean salinity and temperature affect marine organisms at every trophic level in many ways

    • Changes in temperature affect terrestrial organisms at every trophic level in many ways

  • Impacts on Humans

    • Impacts include responses to temperature changes, access to food, access to fresh water, and changing land availability 

  • Anthropogenic activities produce the additional greenhouse gasses that drive climate change

    • Many activities - individual actions, agriculture, industry - produce greenhouse gasses 

Unit 9.5: Global Climate Change

• Historical records about climate change

  • We have records over the past 800,000 years that tell us about regular periods of warming, cooling, and carbon dioxide increase and decrease

    • We get this information from ice cores  in arctic areas

    • We can measure how much carbon dioxide is the ice and how melted it is can tell us about warming or cooling

  • Change in temperature could also cause a change in air circulation, global wind patterns, and soil quality  

• Current data shows that the Earth is warming, which is correlated with an increase in the concentration of greenhouse gasses in the atmosphere

• Effects of climate change include rising temperatures, rising seas levels, and displacement of coastal populations 

• Rising Temperatures Melt Global Ice

  • Melting polar ice reveals darker soil and 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 and food, such as polar bears and seals

• Climate Change Leads to Changes in the World Ocean

  • Climate change leads to sea level rise

    • Benefit - new marine habitat created

    • Drawback - increasing depth of ocean impacts organisms that will no longer be in the photic zone

  • Climate change can alter ocean currents 

    • Salinity and temperature changes impact water density, which can impact the ocean conveyor belt

    • Altered ocean currents can impacts terrestrial climate, especially in coastal areas

Unit 9.6: Ocean Warming

• Ocean Warming - the global increase in ocean water temperatures 

  • The amount of warming isn’t uniform across the globe - some ocean areas have warmed more quickly than others

• Effects of Ocean Warming 

  • Increase in greenhouse gasses can lead to a variety of environment problems

    • Rising sea levels from melting ice sheets and ocean water expansions

  • Thermal expansion of the ocean due to ocean warming causes rising sea levels and displacement of coastal populations due to flooding

  • Ocean warming affects marine species in a variety of ways

    • Loss of habitat

      • Negatively impacts hunting and feeding patterns

      • Can impact predator and prey interactions

      • Affects coastlines that impact species using both land and water resources

      • Can push communities out of the photonics 

      • Impacts primary productivity of phytoplankton, the basis for marine food webs

    • Metabolic Changes

      • Marine species will not be able to escape to cooler areas

      • This could weaken organisms and cause them to die

      • Reduction of biodiversity and disruption of trophic structures 

    • Reproductive Changes

      • Organisms weakened by thermal stress do not reproduce well

      • Many marine reproductive patterns are timed based on specific ocean temperatures - disruption of these temperature patterns leads to reproductive harm

    • Coral Bleaching

      • Warming temperatures stress the corals, they expel that algae that gives them color, giving them a bleached color

      • Can recover, but if conditions persist they will die

      • They are the foundation of highly biodiverse reef ecosystems, their loss will disrupt the trophic structure and has a negative impact on the marine ecosystem 

Unit 9.7: Ocean Acidification 

• Ocean Acidification - the decrease of pH of ocean waters

  • The pH scale is logarithmic- each jump of one on the scale is a tenfold increase, so about a 30% increase 

• Like ocean warming, ocean acidification is due primarily to greenhouse gas concentrations in the atmosphere, specifically carbon dioxide

  • The more CO2 is released into the atmosphere, the more the oceans absorb, lowering their pH through specific chemical reactions

• Anthropogenic activities that contribute to ocean acidification are those that lead to increased CO2, including 

  • Burning/combustion of fossil fuels 

  • Vehicle emissions 

  • Deforestation 

• When CO2 is absorbed by seawater a series of chemical reactions occur which result in an increase in hydrogen ions

• The water combines with the carbon dioxide to create carbonic acid, which is a weak acid. The carbonic acid then dissociates into hydrogen ions and bicarbonate ions

• The greater the concentration of hydrogen ions, the lower the pH of the water (more acidic)

• Effects of Ocean Acidification 

  • Increased concentration of hydrogen ions bond with available carbonate ions in seawater, a bicarbonate ion is formed 

    • Marine organism can’t extract this carbonate, making it difficult for them to build shells and exoskeletons 

    • Corals need free carbonate ions to form skeletons as well

    • This loss of calcium carbonate is very harmful for these organisms

• Oceans absorb carbon dioxide, the more carbon dioxide present, the more they absorb, which warms the ocean 

Unit 9.8: Invasive Species

• Invasive Species - an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health

  • Invasive species can be beneficial sometimes, but they are considered invasive when they threaten native species in some manner

  • Non-native species may be introduced into ecosystems accidentally or purposefully 

  • They tend to be niche, generalist, r-selected species 

    • They can withstand a wide variety of abiotic conditions

    • Can survive on a lot of food 

    • Can produce a lot of offspring in a short time, but there is little parental care

    • Exponential growth, mature very quickly 

  • Not every species that is introduced to an ecosystem becomes invasive 

  • Insavises have a competitive advantage over natives

• How are invasive species spread?

  • Transport of lumber and firepower

  • Ballast water in ships, movement of boats and boat trailers, international travel as well 

  • Movement of wind and water

  • On the fur of other animals

• How to Control the Spread

  • Clean boats and boat trailers 

  • Prevent dumping of aquariums and release of exotic pets 

  • Clean hiking gear before going into a new hiking area 

  • Keep firewood wear it was cut to prevent spread of wood-borne pathogens

• How can we Control the Spread?

  • Introduce a competitor species

  • Introduce a predator species

  • Introduce a virus 

  • Physically remove them

  • Release a pesticide to control their spread

Unit 9.9: Endangered Species

• Factors that Lead to Extinction 

  • As habitats are lost or altered globally, many species are threatened with extinction 

  • Extensive Hunting

    • Poaching is illegal hunting, killing or capturing of animals for sale of profit

    • Animals are hunted for food, prized body parts, traditional medicinal uses 

    • Medical research purposes 

    • Sport

  • Limited Diet & Habitat

    • Species who are niche specialists are generally at greater risk of extinction

    • These species typically need specific materials for their diet and habitat to survive, and do not reproduce quickly 

  • Outcompeted by Invasive Species

    • Invasive species have little diet and habitat requirements, so they can out-adapt and out-compete some native species that have a limited lifestyle

• The biological and behavioral traits of a species will determine their risk of extinction when exposed to environmental change 

  • Species that can adapt to these changes better have less of a chance of becoming extinct 

  • Adaptation requires genetic diversity

• Species can migrate to a more favorable environment to avoid extinction, but this could also raise competition in the new environment

• Selective Pressure - any external factor that changes the behavior and fitness of organisms within an environment

  • Examples include 

    • Resource Availability 

      • Food

      • Water

      • Habitat

      • Mates

    • Abiotic Environmental Condition 

      • Temperature 

      • Humidity 

      • Tree cover

      • Salinity

    • Biological Factors

      • Pathogens (viruses, bacteria, and fungi)

      • Diseases

  • Selective pressure determine which genetic and behavioral traits are favorably adapted to the environment and which aren’t 

  • Pressures will change in changing environments, so traits that were once advantageous in an environment may not continue to be so

• Competition can occur within or between species in an ecosystem where there are limited resources 

  • Species seek to limit competition because it’s biologically costly 

• Competition consumes important metabolic resources, so competitive strategies generally evolve to a limit resource conflicts through resource partitioning 

• Organisms may compete within their own species resources, such as 

  • Territory 

  • Food

  • Mates

  • Habitat 

• Competition can become intense enough to eat to a species’ endangerment or extinction when:

  • Trophic relationships are disrupted 

  • There is increased competition invasive species 

  • Resources have become increasingly scarce due to habitat loss or climate change 

• Strategies to Protect Species

  • Legislation - (with enforcement) is one primary way to help protect endangered species 

  • Criminalizing poaching and instituting steep fines and/or punishment for poachers can help curb this practice 

  • Laws prohibiting the harming of endangered species and their habitats, or trade in endangered species 

    • The Lacey Act

    • The Endangered Species Act 

    • The Marine Mammal Protection Act

    • CITES (the Convention on International Trade in Endangered of Wild Fauna and Flora)

  • The establishment of protected areas for species, such as wildlife refuges or national parks

    • Enforcement of conversation practices help as well

Unit 9.10: Human Impacts on Biodiversity 

• HIPPCO - an acronym regarding the main factors leading to decreases in biodiversity

  • Habitat destruction 

  • Invasive species

  • Population growth

  • Pollution

  • Climate change

  • Over exploitation 

• Habitat Fragmentation

  • Occurs when large habitats are broken up into smaller, isolated area

  • Caused by construction of roads and pipelines, clearing of land for agriculture, and logging

  • Not all species are equally impacted by this 

    • Generalists who thrive in abiotic conditions, or species that thrive in areas where two habitats meet can adapt to fragmentation

    • Specialists with specific habitat requirements suffer more

  • Generally decreases biodiversity despite some generalist species having an increase in population

• Climate Change and Habitat Loss

  • Global climate change plays a large role in habitat loss

  • As average global temperature rises, habitats may be lost due to 

    • Coastal inundation from melting ice and permafrost

    • Rising sea levels due to thermal expansion

    • Changes in precipitation patterns due to changing atmospheric and oceanic circulation patterns

  • Climate change has been most intense in northern latitudes; as warming trends continue, these areas will be at most risk for habitat loss and loss of biodiversity 

• Domestication and Loss of Biodiversity

  • Humans have been domesticating organisms for thousands of years

  • Domestication - involves artificial selection, in which organisms with the most desirable traits for humans are crossbred to enhance the occurrence of that in the species

  • Many domesticated species are managed for economic returns, and provide humans with 

    • Food

    • Medicine

    • Labor

    • Pollination Services

  • When humans assume responsibility for the reproduction and selection of traits in another species, genetic diversity will be reduced 

    • Domestication for economic return leads to a loss of biodiversity 

    • Examples of this can be seen in domestic livestock (cattle, sheep, goats, pigs), honeybees, and the agricultural practice of monocropping

• Strategies to Mitigate Biodiversity Loss

  • As global climate change intensifies, it is important that we address current and future losses of biodiversity. Strategies include:

    • The creation of protected areas, such as wildlife refuges and parks

    • The creation of habitat corridors to reduce the negative effects of habitat fragmentation

    • Restoration of lost habitats

    • Sustainable land use practices