Jan. 9, 2024

Our environment includes all of Earth’s biotic components and the abiotic components with which we interact. There needs to be a clear, comprehensive definition of the environment because there are legal, social and economic aspects; it’s not just science.

Environmental science is the study of how the Earth’s natural systems function, how humans are influenced by those systems, and how we are influencing those systems.

Science is a systematic process for learning about the world and testing the understanding. Science can also refer to the accumulated body of knowledge that results from that process.

*When discussing topics in this field, do not use the word “problems”. Instead replace it with “issues”.

Environmental Science is not Environmentalism. It focuses on the pursuit of knowledge about the natural world; scientists try to remain objective.

Environmentalism is a social movement dedicated to protecting the natural world.

Environmental science is not ecology. Environmental science is interested in human impacts on these ecosystems and is interested in the consequences for humans.

Perspectives and worldviews

• Decisions are shaped by both knowledge and ethics
• How to quantify value?
  • Utilitarian value: importance to human welfare
  • Ecological value: importance to humans and to natural ecosystems
  • Intrinsic value: individual organisms or species or natural ecosystems have an inherent right to exist
• Values often reflect different world views
• Anthropocentric worldview
  • Human needs are the most important consideration
  • Set values according to implications for people
• Biocentric worldview
  • All species and individual organisms have intrinsic value
  • Humans unique/special but not more “worthy” than other species
• Ecocentric worldview
  • Values connections among species and non-living ecosystem components
• Frontier worldview
  • Humans have a right to exploit nature without constraint
  • Resources are unlimited because we can always find new stock or substitutes
• Sustainability world view
  • Moderate resources exploitation according to ecological/intrinsic/aesthetic values
  • Can be anthropocentric or ecocentric
• Management worldview
  • Treating the planet like a factory; how many resources can we pull out of the planet?
• Stewardship worldview
  • Possessing an ethical responsibility to care for nature
  • Encouraging environmentally beneficial forms of economic growth and discourage environmentally harmful forms
• Environmental wisdom worldview
  • Nature exists for all species, humans are not incharge of earth

Jan. 11, 2023

Sustainability: resources and impacts

• Resources
  • Perpetual vs renewable vs non-renewable
  • Goods, services and intrinsic value
  • Carrying capacity and the tragedy of the commons
  • Perpetual resources: resources that you're unable to change or impact; resources that last forever (ex. Sunlight, wind, etc.)
• Human impacts
  • Population growth and technological advances
  • IPAT and ecological footprints
  • Ecological footprints and biocapacity

Non-renewable resources

• Supply can be depleted; the resource does not replenish itself
  • Oil, coal, minerals
• Once used, the resource is no longer available as it will not be replenished during the lifetime of humans
• Mined rather than harvested

Renewable resources

• The stock is the harvestable portion of the resource
• Overharvesting = stock depletion
• Renewable resource management
  • Balance the use of a resource with its protection and preservation
  • Rate of use < rate of replenishment = sustainable
  • Rate of use > rate of replenishment = environmental degradation (stock depletion)
  • “Natural capitol” = living off the interest of sustainable resources
  • The concept of stock depletion also applies to abiotic resources

Resources as goods and services

• Goods
  • Tangible material things
  • Extracted from the environment
  • Food, water, minerals, etc.
• Services
  • Functions and processes vital to living organisms
  • E.g. soil recycling, climate regulation
  • Hard to put a price on

*Money isn't the money measure of value. There is also intrinsic value: the notion that something has a right to exist independent of its value to people.

Tragedy of the commons

• Unregulated exploration leads to resource depletion
• Resource users are tempted to increase use until the resource is gone
• What is the solution?
  • Private ownership
  • Voluntary organization to enforce responsible use?
  • Governmental regulation?

Carrying capacity

• Carrying capacity is a measure of a systems ability to support life

# of individuals of a species that can be sustained by the biological productivity of a given area of land

• • Earth's carrying capacity is limited

Human activities

• Human activity affects the environment
• But people's perceptions/values vary
• People can disagree about what constitutes a problem
• Increase in human population = increase in human impacts

Human impact involves more than population size

• IPAT
  • Total impact (I) on the environment as the product of population (P), affluence (A), and technology (T)
  • Population (P) x Consumption per person (affluence, A) x Technological impact per unit of consumption (T) = environmental impact of population (I)
  • I = P x A x T

*affluence defines how wealthy someone is

Ecological footprint

• Environmental impact of an individual or population
• Amount of biologically productive land and water required to provide the raw materials a population consumes and absorb the waste produced
• Opposite of carrying capacity

Jan. 15, 2023

Ecological footprint continued

Biocapacity: The capacity of a terrestrial or aquatic system to be productive and to absorb waste, including CO2

- Humans have surpassed planets biocapacity

Sustainability

• Related to carrying capacity
• An environmentally sustainable society preserves its natural capital and lives off its income
• Sustainable development uses resources to satisfy current needs without compromising the future availability of resources
• Often think of sustainable solutions as meeting

- environmental goals

- economic goals

- social goals

• “strong sustainability” recognizes that economic and social systems can only function within the limitations of the natural world

Science as a process

• Make repeated specific observations
• Collect data
• Generalize from the data
• Inductive reasoning
• Observations and inductive reasoning leads to questions
• Form logical hypotheses (tentative answers)
• Make predictions
• Deductive reasoning
• Test predictions using new observations and experiments

*an observation may lead to multiple hypotheses

• Failure to falsify a hypothesis does not prove it true
• You can never prove a hypothesis true
• But testing in many ways can increase confidence

Jan. 16, 2024

Peer-reviewed literature vs Grey literature

• Grey literature
• Grey literature sources include materials produced by government ministries, NGOs, industry, etc.
• Not necessarily unreliable, but has not passed through peer review and is not consistently indexed or organized
• Government and NGO reports, statistics, patents, conference papers

Primary, secondary and tertiary literature

• Primary
  • Describes original research; first hand information; describes hand on results of getting new information
  • Includes research papers in peer-reviewed journals, dissertations, technical reports, conference proceedings
  • Papers in peer reviewed journals usual;y have a distinctive structure
    • Abstract
    • Introduction
    • Methods
    • Results
    • Discussion
    • Literature cited
• Secondary
  • Interprets and synthesizes primary sources
  • Includes review articles, meta analysis, monographs and specialist textbooks
  • May be published in peer review journals
  • May have the same structure as primary research papers
• Tertiary
  • Provides summaries and condensed versions of primary and secondary literature
  • Includes textbooks, dictionaries, encyclopedias

Consensus science, frontier science, junk science

• Consensus (sound) science
  • theories and data that are widely accepted by scientists who are experts in the field
• Frontier science
  • not yet widely tested
  • Still a topic of dispute among researchers in a field
• Junk science
  • Content that is misleadingly presented as sound science, e.g., that hasn't been subject to peer reviews
    • Problems when junk science is presented as sound
    • Problems when sound science being presented as junk

Source credibility

• 5 Ws
  • Who is the author? Authority
  • What is the purpose of the content? Accuracy
  • Where is that content from? Publisher
  • Why does the source exist? Purpose & objectivity
  • How does the source compare to others? What’s what
• SMART
  • Source
    • Who or what is the source?
  • Motive
    • Why do they say what they do?
  • Authority:
    • Who wrote it?
• Review
  • Does anything jump out as untrue?
• Two source Test
  • • How does it compare to another source?
• CRAAPO
  • Currency
    • How timely is the information?
  • Relevance
    • How important is the info to your needs?
  • Authority and credibility
    • Source of the information (author and publisher)
  • Accuracy & Reliability
    • Truthfulness/correctness of the information?
    • Is it well researched?
• Purpose & Intended Audience
  • Reason the information exists
  • Objectivity & bias
  • Objective vs. subjective, opinion vs fact, author’s agenda

Jan. 22, 2024

Testing hypotheses: observation vs. experimentation

• Look for, or create variation in the hypothesized causal factor (the independent variable)
• And measure the effect on the dependant variable
• In a manipulative experiment (aka controlled experiment), you manipulate the dependant variable
  • Establishes causation, bt may not be impossible
• Observational studies use naturally occurring variation on the dependant variable
  • Correlative, but preserves real world complexity

*in the context of science, a theory is broader in scope than a hypothesis, general and can lead to new testable hypotheses and supported by a large body of evidence in comparison to hypothesis

Systems and models

• A system is combination of regularly interacting parts or components that form a collective entity
• Synergistic interactions occur when processes interact, such that the whole is greater than the sum of the parts
  • Collective properties are based on the summation of the parts, e.g. # of animals in a population
  • Emergent properties arise from interactions among the parts, e.g. from competition, predation, mutualisms
• Systems have inputs, flows (throughouts) and outputs
• A system may interact with other systems
• Open stems exchange energy and matter with other systems
• Closed systems receive energy inputs and produce energy outputs but do not exchange matter with other systems
• Complex systems have multiple subsystems
  • Environmental entities are complex systems with interact with each other
  • E.g., river systems consist of hundreds of smaller tributary subsystems
  • To solve environmental problems, all appropriate systems must be considered

Feedback loops

• Environmental systems often contain feedback loops
• Feedback loop: a systems output serves as input to the same system
• Positive feedback loop
  • Feedback from the initial change pushes the system further towards one extreme or the other
  • E.g., melting glaciers and sea ice
• Negative feedback loop
  • Output that results from a system moving in one direction acts as input that moves the system in the other direction
  • Neutralize one another's effects
  • E.g., thermostat, predator prey system

Time delays and tipping points

• Homeostasis: a system maintains constant or stable internal conditions, e.g., through negative feedback loops
• Time delays between stimulus and response affect feedback loops
• Tipping points are thresholds beyond which a system's behavior changes
• Resistance vs resilience

Jan. 23, 2024

Matter

• Matter is all material in the universe that has mass and occupies space
• Building block types of matter are elements (individual building blocks are atoms)
• Matter cannot be destroyed or created
  • Law of conservation of matter

Organic matter

• Organic compounds are based on curtains or carbon atoms
  • May include other elements such as nitrogen, oxygen, sulfur and phosphorous
• So, water (H2O) is inorganic
• Hydrocarbons contain only carbon and hydrogen
• Most organic molecules are pliers, i.e., chains of similar subunits
• Proteins are chains of amino acids
• Primary protein structure: sequence of a chain of amino acids
• DNA & RNA are chains of nucleotides
• Carbohydrates are chains of simple monosaccharides
• Plastics are synthetic (human-made) polymers
  • Nylon, teflon, kevlar
  • Many are derived from petroleum hydrocarbons

Energy

• Energy is always conserved
  • I.e., the total amount of energy in the universe is fixed
  • First law of thermodynamics: energy cannot be created or destroyed
• But energy can change form one form to another, and when it does:
  • Second law of thermodynamics: when energy is changed from one form to another, some useful energy will change to lower-quality, less useful energy
• Entropy: systems tend to move toward increasing disorder (organized to unorganized)
• And yet, life is highly organized
• To stay organized, living things use solar energy either directly or indirectly

*Characteristics of matter and energy are essential to understanding the ecosystem process

Ecosystems

• Ecosystem: all organisms and nonliving entities that occur and interact in a particular area at the same time
  • Includes abiotic and biotic components
  • Ecology: the study of interactions of organisms with one another and their abiotic environment
• Ecosystem ecology: study of energy and material flow among biotic and abiotic components of systems
• Structure and functional processes
• Energy flows through ecosystems and is processed and transformed
• Matter is recycled within ecosystems
• At a planetary scale, the ecosphere includes a biotic compartment; the biosphere and different abiotic compartments; lithosphere, hydrosphere, atmosphere

Jan. 25, 2024

Energy flows

• Energy Flows through ecosystems and is processed and transformed

Producers

• Autotrophs are producers
  • Produce their own “food” from the sun's energy
• Photosynthesis
  • Turns light energy from the sun into chemical energy
• Chloroplasts
  • Organelles in plant cells that use the energy to link together carbon atoms from CO2

Consumers

• Heterotrophs are consumers
  • Obtain energy and nutrients from organic matter
• Heterotrophs include
  • Herbivores
  • Carnivores
  • Detritivores
  • Decomposers
• Break down glucose, releasing CO2 (aerobic respiration)

Food chains and food webs

• Food chains are simplified description of how matter and energy move through an ecosystem
• Organisms are assigned trophic levels based on who eats who

• Food webs capture some of the complexity missing from food chains

Ecological efficiency

• Ecological efficiency = % of usable energy transferred from one trophic level to the next
  • Typically 10% (range 2-40%)
• Energy flow pyramid/productivity pyramid

Productivity

• Gross primary productivity (GPP)
  • Rate at which primary producers convert solar energy into chemical energy (i.e., biomass)
• Net primary productivity (NPP)
  • GPP minus rate at which producers use stored energy or metabolic needs/aerobic respiration
• NPP sets an upper limit on populations of consumers

Variations in productivity

• High net primary productivity: ecosystems whose plants rapidly convert solar energy to biomass

Limits

• Nutrient availability can limit productivity
  • Nutrients: elements and compounds required for survival that are consumed by organisms
    • Macronutrients: nutrients required in relatively large amounts (nitrogen, carbon, phosphorus)
    • Micronutrients: nutrients needed in smaller amounts

Energy flows; matter cycles

• Matter is recycled within ecosystems

Jan. 29, 2024

Biogeochemical cycles (nutrient cycles)

• Movement of nutrients through ecosystems
  • Atmosphere, hydrosphere, lithosphere and biosphere
• Pools (reservoirs): where nutrients reside for varying amounts of time
• Flux: movement of nutrients among pools, which change over time and are influenced by human activities
• Sources: pools that release more nutrients than they accept
• Sinks: accept more nutrients than they release
• Hydrologic cycle
• Carbon cycle
• Nitrogen cycle
• Phosphorus cycle

Hydrologic cycle

• Water is essential for biochemical reactions and is involved in nearly every environmental system
• Damming rivers increases evaporation and infiltration
• Altering the surface and vegetation increases runoff and erosion
• Spreading water on agricultural fields depletes rivers, lakes and streams
• Removing forests and vegetation reduces transpiration and lowers water tables
• Emitting pollutants changes the nature of precipitation
• Possibly our most serious impact is overdrawing groundwater for drinking, irrigation and industrial use

Carbon cycle

• Carbon is the foundation for living organisms
  • Found in carbohydrates, fats, proteins, bones
• Most carbon is associated with sedimentary rock
• Burning fossil fuels moves carbon from the ground to the air
• Cutting forests and burning fields moves carbon from organisms to the air
• Today’s atmospheric CO2 reservoir is the largest in the past 650, 000 years
  • Driving force behind climate change
• Missing carbon sink puzzle: > 2 billion metric tons of carbon per year unaccounted for
  • May be in plants or soils of northern forests

Nitrogen cycle

• Nitrogen is a big part of many organic molecules, especially proteins
• Nitrogen is 78% of the atmosphere but N2 gas is inert
  • Nitrogen fixation: nitrogen gas is mixed (made into ammonia (NH3)) by nitrogen-fixed bacteria
    • Ammonium ions (NH4+) are usable by plants

• Synthetic production of fertilizers by combining nitrogen and hydrogen and synthesize ammonia
  • Humans are fixing as much nitrogen as nature does
  • Farming legumes
• Agricultural runoff “fertilizers” aquatic systems
  • Algal blooms are followed by die-offs
  • Decomposition creates BOD (biochemical oxygen demand)
  • Reduces dissolved oxygen in water (hypoxia)

Eutrophication

• Nutrient over-enrichment leads to blooms of algae, increased production of organic matter, ecosystem degradation
• 

Jan. 30, 2024

Phosphorus cycle

• Phosphorus (phosphate) is a key component of cell membranes, DNA, RNA, ATP and ADP
• Phosphorus is not naturally occuring, what you are finding/seeing is actually phosphate
• Most phosphorus is within rocks and released by weathering
• Because environmental concentrations are naturally low, phosphorus is a limiting factor for plant growth
• Food webs: plants take up phosphorus when it is dissolved in water
• Very slow process
• Mining rocks for fertilizer moves phosphorous from the soil to water systems
  • Wastewater discharge also releases phosphorus
• Runoff containing phosphorus causes eutrophication of aquatic systems
• Household detergents maye contain phosphorus
• Nitrogen and phosphorus are responsible for the gulf of maine dead zone due to spreading nitrate and phosphate across the land

Evolution

• Evolution: changes in a population's genetic makeup through successive generations: genetic change over generations
• Genes mutate; individuals are selected; populations evolve
  • Microevolution: small genetic changes within a population that do not give rise to new species
    • Every population has a gene pool made up of all the different versions of each gene (alleles) = genetic diversity
    • Mutation causes random changes in DNA sequences; mutation is the ultimate source of genetic diversity
    • Evolution through natural selection occurs when variability in a heritable trait leads to differential reproduction
    • Adaptive trait increase lifetime reproductive success by increasing survival or reproductive rate
    • Natural selection can be directional, stabilizing or diversifying

• • Speciation: changes leading to new biological species (populations that can't interred with one another)
    • Can be allopatric or sympatric
    • Allopatric: two different population heading off in different directions
    • Sympatric: two species appear within a single population
    • Biological species concept: species are groups of populations that are reproductively isolated from one another; cannot have fertile offspring if mated

• • Macroevolution: long-term, large-scale changes in the number and types of species

Feb. 1, 2024

Extinction

• Extant: a species still living somewhere
• Extirpated: no longer living in a specific place
• Extinct: no longer living at all
• All species evolutionarily become extinct, leading to a background extinction rate (likewise, background speciation rate)

Macroevolution

• Big changes in the diversity of life (above the species level)
  • Mass extinctions, e.g., due to planet-wide environmental change
  • Adaptive radiations (rapid speciation within a lineage)

Ecological niches

• An ecological niche is a species role/ way of life
  • Includes all the factors that affect its survival and reproduction
  • A habitat a is a species’ address; a nice is its occupation
• Niche overlap
  • Fundamental niche vs realized niche
• Niche breadth
  • Generalists vs specialists
• Convergent evolution
  • Similarities evolve in distantly related species due to similar environment constraints or opportunities
  • Same problem -> same solution

Evolution misconceptions

• Individuals evolve
• Goal oriented; e.g., “fish evolved a torpedo shape so they could swim faster”
• Survival of the strongest
• Evolution will find a way

Feb. 5, 2024

Global biomes (terrestrial)

• Biomes are geographically extensive (global) ecological units associated with particular environmental conditions
• Biomes exhibit characteristics difference in mature vegetation
• “Mature vegetation” = types of plants, not species

• Terrestrial biomes result from differences in temperature, precipitation (& seasonality)

Ecoregions (ecozones)

• Ecoregions are based on species composition
• There are 867 identified ecoregions
• NLFLR: “ecoregions are areas that have distinctive, recurring patterns of vegetation and soil development, tha are determined nd controlled by local climate and geology.”

Living in water vs living on land”

• In water~ positives
  • Supper; facilitates dispersal
  • Constant temperature
  • Dissolved nutrients and water
  • Protects from UV radiation
  • Dilutes and disperses pollutants
• In water~ negatives
  • No tolerance for temperature fluctuations
  • Limited light and oxygen
  • Exposure to dissolved pollutants

Different types of aquatic life

• Plankton
  • Phytoplankton (plant like plankton)
  • zooplankton (animal like plankton)
  • Ultraplankton (very small)
• Nekton
• Benthos

Aquatic life zones: marine and freshwater

Feb, 8, 2024

Freshwater: lentic and lotic

• Characteristics of lentic systems depend on nutrients and on water transparency
• Horizontal and vertical zonation (littoral, limnetic, profundal, benthic zones)
• Characteristics of lotic systems depend on flow volume, velocity and seasonality

Wetlands

• Wetlands are shallow, flooded areas
  • Waterlogged soil = different vegetation
• Bogs get water from rain
  • Acidic
  • Sphagnum moss partially decomposes to peat
• Fens are fed by moving ground water
  • Less acidic; more nutrients
• Marches are often near lake or river banks
  • Dominated by herbaceous plants
• Swamps are permanently waterlogged
  • Forested wetlands

Marine (ocean)

• Marine systems require yet another perspective: tides, currents, salinity, nutrients, light
• Open ocean: biggest distinctions relate to depth
• Continental shelves can be more productive, especially of upwelling current provide nutrients
• Seashores differ depending characteristics of the physical environment
  • oxygen , light, temperature, nutrients

Anthropogenic ecosystems

• Characteristics of human dominated ecosystems are due to human activity (intentional or not)
  • Urban-industrial techno-ecosystems
  • Rural techno-ecosystems
  • Agroecosystems

Feb. 12, 2024

Populations

• Species: an aggregation of individuals and populations that can potentially interbreed and produce fertile offspring, and this is reproductively isolated from other such groups
• Population: individuals at the same species that occur together in time and space
  • So, species may consist of multiple populations that are geographically isolated together
• Community: a group of populations of organisms that live in the same place at the same time
  • Community ecology focuses on interactions among population of different species

Characterizing communities

• Physical appearance/structure
  • Affects species composition and interactions
  • Pathiness and edges
• Diversity
  • Richness vs evenness vs diversity
• Niche structure

Characterizing diversity

• Species diversity
  • Richness vs oneness vs diversity
    • Richness: how many species are present
    • Evenness: how many of each species are there? Is each even with each other?

Biodiversity tangent

• What determines diversity?
  • Why is species diversity greatest in the tropics?
    • Area (habitat diversity)?
    • Primary productivity?
    • Time?
    • Disturbance frequency?
  • Bigger islands have higher species richness. Why?
    • Island biogeography (species equilibrium model)
    • Equilibrium between rates of immigration and extirpation
    • Equilibrium depends on island size and distance from the mainland

Implications for reserve/park design: single large or several small (SLOSS)

• A single, big reserve has proportionately more interior habitat
• A curricular reserve has proportionality mor interior habitat than a skinny reserved
• Clumps reserves with connecting corridors to allows for recolonization

Mutualism

• Two or more species benefit from their interactions
  • E.g., pollination: bees, bats, birds, and others transfer pollen from one flower to another
• Symbiosis: a general term for interactions in which two organisms live in close physical contact

Commensalism

• One organism benefits; the other is unaffected
  • E.g., plants create shade for animals

Amensalism

• Not clear whether this ever happens (Large herbivore eating plant with small insects on it? Tree shading grass?)
• One species is destroyed or inhibited and the other remains unaffected

Feb. 13, 2024

Parasitism

• One organism (parasite) depends on another (host) for nourishment or another benefit
• Can be internal (malaria, tapeworm)
• Or free living (ticks, lamprey)
• Some cause little harm and others kill their host (parasitoid)
• Coevolutionary “arms races” between parasites and their hosts

Predation

• Individuals of one species capture, kill, and consume individuals of another species
• One of the primary organizing forces in community ecology
• Predator-prey interactions structure food webs and influence community composition
• Various adaptations are associated with predator-prey interactions
• Predator-prey interactions can drive population dynamics
  • E.g., cycles in population size

Herbivory

• Animal feeds on plant tissue
• Doesn’t necessarily kill the plant, but affects growth and survival
• Plants revolve various defenses
  • Toxic chemicals
  • Spines, thorns, hairs
  • Mutualisms with other species that protect the plant

Competition

• Multiple organisms seek the same limited resources
  • Food, water, space, shelter, mates, sunlight
• Can be intraspecific or interspecific
• Interspecific competition can lead to either competitive exclusion or to species coexistence
• Coexisting species may reach some equilibrium, that's different than either species would reach in isolation
• For coexisting species, the realized niche may differ from the fundamental niche
• Over evolutionary time, competition leads to resource partitioning and character displacement
• Trophic level refers to a rank in the hierarchy
  • Producers
  • Consumers
  • detritivores/decomposers

Disturbance and succession

• Disturbance; an environmental change that disrupts as community
• Succession: a predictable series of changes in a community following a disturbance
  • Primary succession: happens when disturbance eliminates all vegetation and/or soil life
  • Secondary succession: happens when disturbance dramatically alters, but does not destroy all local organisms
• Resistance and resilience as responses to disturbance
• Primary succession occurs after a disturbance eliminates all vegetation and organic material
  • Retreating glaciers, volcanic activity, really intense fires

Primary succession

• First species to appear are usually pioneer species
• Early succession; stages are mostly herbaceous annuals
• Late successional stages are longer levied and shade tolerant

UNSURE OF DATE, NOTES MISSED

Secondary succession

• Occurs after a disturbance drastically alters, but doesn’t destroy local organisms
  • E.g., hurricane, fire, old field
• Facilitation: one stage creates conditions that make an area suitable for the next, e.g., lichens build up soil
• Inhibition: one stage create conditions that hinder other species
• Tolerance: later stage is unaffected by earlier

Succession

• Used to think that succession led to a climax community
• Now view succession as more complex and influenced by chance; maybe different climax communities are possible; maybe a mosaic of vegetation matches in a mature community

Characterizing species roles

• Functional niche
  • E.g., herbivores, carnivores, detritivores; herbaceous plants, shrubs, trees; scarpers, grazers, collectors, predator
• Keystone species have especially strong, or far-reaching effects on their communities
  • E.g., wolves, sea stars, sea otters
  • Effects can involve trophic cascades \

Foundation species and ecosystem engineers

• Foundation species shape communities by creating/modifying habitat

Indicator species

• Indicator species presence/abundance is correlated with some aspect of environmental quality

Non-native/introduced/invasive species

• Invasive species are on-native (exotic) species that spread widely and become dominant in a community
  • Growth-limiting factors (predators, disease) are absent
  • Major ecological effects
• Control manually, or with toxins, or with various specialized treatments

Stability and complexity

• Stability is some combination of
  • Interia: persistence, resistance to perturbation
  • Resilience: ability to recover from perturbation
  • Constancy: consistency, e.g., size of a population
• Unclear whether stability increases with complexity; may depend on how you measure things

Ecological restoration and the precautionary principle

• Restoration ecology: the science of restoring an area to the condition that existed before humans changed it
  • Often not possible
  • Difficult, time consuming, expensive
  • Better to protect natural systems from degradation in the first place
• How do you pick an original state?
• Precautionary principle: if we don't completely understand casual relationships, best to err on the side of caution

Populations

• Species: an aggregation of individuals and populations that can potentially interbreed and produce fertile offspring, and that is reproductively isolated from other such groups
• Population: individuals of the same species that occur together in time and space
• So, species may consist of multiple populations that are geographically isolated from one another

Population size

• Population size refers to the number of individuals present at a given time
• Numbers can increase, decrease, remain stable, or cycle

Population density

• Population density: number of individuals per unit area
  • High densities make it easier to find mates, but increase competition
  • At low densities, each individual may enjoy plentiful resources

Population distribution

• Population distribution: spatial arrangement of organisms within an area; aka dispersion
  • Random: haphazardly located, with no pattern
  • Uniform: evenly spaced
    • Why?
  • Clumped: aggregated (form into a group or cluster)
    • Most common

Demography

• Sex ratio: proportion of males to females
  • 50:50 is common (for evolutionary reasons); in monogamous species, 50:50 sex ratio maximizes population growth
• Age structure: the relative numbers of organisms of each within a population

Changes in population size

• Populations may grow, shrink, or remain stable
• Natality: births within the population
• Mortality: deaths with the population
• Immigration: arrivale of individuals from outside the population
• Emigration: departure of individuals from the population
• Population growth rate formula:
  • (Crude birth rate - crude death rate) + (immigration rate - emigration rate) = population
• BIDE models
• Unregulated population increase by exponential growth
• Steady growth rates cause exponential population growth
  • Something increases by a fixed percent
  • Graphed as a J-shaped curve
• Exponential growth cannot be sustained indefinitely
  • It occurs in nature with a small population and ideal conditions
• Limiting factors determine carrying capacity and restrain population growth
• Carrying capacity: the maximum population size of a species that its environment can sustain
• An S-shaped logistic growth curve
• Limiting factors slow and stop exponential growth
• Carrying capacity changes
• Don't usually see perfect logistics growth
• de density-dependent factors: limiting factors whose influence is affected by population density
  • E.g., at high densities, competition for resources reduces survival or reproduction
• Density-independent factors: limiting factors whose influence is not affected by population density
  • E.g., floods, fires, weather

Variation in reproductive strategies

• Biotic potential: the ability of an organism to produce offspring
• K selected species: long gestation periods and few offspring
  • Low biotic potential
  • Stabilize at or near carrying capacity
  • Good competitors
• R-selected species: reproduce quickly
  • High biotic potential
  • Little parental care

March 4, 2024

Human population growth

• Massive increase in number of people is relatively recent
  • Global pop’n < 1 million for most of human history
  • Big pop’n increase starts ~10,000 years ago
• Can use doubling time to quantify change in rate
• Population increases made possible by cultural evolution, leading to spread of key innovations
  • Industrial and medical technological revolutions
• Number of people is an order of magnitude greater than any other large, wild mammal
• Also have huge numbers of larger domesticated mammals
  • 1.5 billion cows
  • 1.2 billion sheep
  • 1 billion pigs
  • 1 billion goats
  • VERSUS
  • 60 million bison
  • 60 million white tail deer
  • 60 million kangaroos

Variation among countries

• Natural rate of increase = births - deaths
• Total factors in immigration and emigration

March 5, 2024

Demographic transition

• Less developed societies have generally had high birth rates and high death rates, e.g., 40-50 per 1000 people per year
• Birth rate, at least initially stays high
• Later, birth rates decline
• Developed soceieties have low birth rates and low death rates

*ignoring carrying capacity, future population size depends on population policies

Demography

• Describe population age structure
  • How many biological males and females in different age categories?
  • Representative: 0-14
  • Reproductive: 15-44
  • Post Reproductive: 44 and up

Demography and the demographic transition

• Age class structure differs on either side on the demographic transition; helps with understanding delayed responses to population policies

Carrying capacity

• How many people can the world support?
  • Ecological footprint models
• If there are too many people, what should we do about it?
  • Should societies enact policies that restrict family size
  • Effects of social changes and development
  • Gender equality and access to family planning
• Is carrying capacity the right metric?

Potential causes of a human population crash

1. Pandemic

• E.g., bubonic plague (black death) in europe: 85 million → 60 million
• E.g., smallpox
• E.g., spanish influenza (20-4- million deaths)
  • Huge impact on some NL communities
• E.g., HIV-AIDS
  • Developed countries have good access to antiretroviral drugs; still a huge issue in less developed countries

1. Famine, risk factors include

• Large, dense population
• Limited food reserves
• Agriculture in marginal areas
• Social, political and economic factors

1. Reduced carrying capacity
2. Nuclear accident
3. Natural disaster unrelated to population size (e.g., meteorite)

March 7, 2024

*Midterm covers material starting from biomes and aquatic life zones to communities then populations and then human populations

Factors associated with:

• Higher biodiversity
  • Middle stage of succession
  • Moderate environmental disturbance
  • Small environmental changes
  • Physically diverse habitat
  • Evolution
• Lower biodiversity
  • Extreme environmental conditions
  • Large environmental disturbance
  • Intense environmental stress
  • Simplified habitat
  • Introduction of non-native species
  • Geographic isolation

Canada’s forests

• 25% of earth's natural forest (310 million ha)
• More forested land per capita than any other country
• 50% of canadian forest is still intact

Ecological importance

• Structural complexity → many different habitats → biodiversity

Ecosystem services

• Stabilizes soil; prevents erosion
• Slows runoff, lessens flooding
• Purifies water
• Stores carbon, releases oxygen
• Moderates climate

Forest products/economic importance

• Fuel, shelter, transportation, paper
• Softwood: timber from coniferous forests
• Hardwood: timber from deciduous/broadleaf forests
• NTFP (non-timber forest products): medicines, herbs, decorative, edibles)

Old growth vs second growth vs plantation

• Old growth
  • 36% of earth's forests
  • Undisturbed for hundreds of years
• Second growth
  • 57% of earth's forests
  • Resulting from secondary succession
• Tree plantations
  • 7% of earth's forests
  • Managed tract, trees of uniform age

Harvest methods

• Clear cutting: remove all trees at once, often in blocks
  • Cost efficient
  • Some trees like lots of light (black spruce)
  • Greatest impacts on forest ecosystems
  • Mimics some natural disturbances, e.g., fire
  • Increase soil erosion
• Seed-tree cutting
  • Remove almost all the trees
  • Seeds from remaining mature trees help to regenerate the forest
  • No longer have a forest
  • Potential for erosion
• Shelterwood cutting
  • Remove ⅓ of threes then wait 10 years
  • Repeat
  • Remove a final 1/1, but by that time, more young and intermediate trees have grown back
  • Still have a forest and limited erosion
  • Some trees like moderate light (red oak, white pine)

Harvest methods

• Selection cutting: start with an uneven-aged forest and selectively cut some intermediate aged or mature trees
  • Encourages growth of young trees
  • Limits erosion and wind damage
  • Still have a forest
  • Some trees grow best under a canopy (birch, maple)
• Strip cutting: clear-cut one strip and leave an adjacent strip uncut
  • Uncut strips help regenerate the harvested strip
• Clearcutting alternative are different ways to mimic natural disturbances/lessen ecological impact
• Even aged stands vs uneven
• Reforestation (tree planting) produces a tree plantation rather than a forest
• Maxim sustainable yield (MSY)
  • Cut as much as the forest produces in a year
  • Cut trees as soon as they've completed their fastest stage of growth (intermediate staged)
    • Removes habitat for species that need old trees

Missed notes

Degradation of forest roads

• Erosion and sediment runoff
• Habitat fragmentation
• Pathways for non-native species introductions
• Accessibility for human activity and development
• Forestry creates habitat islands

Pests

• Outbreaks of insect species that feed on tree species
• Some are native
  • E.g., tent caterpillar, spruce budworm, mountain pine beetle
• Others are non-native
  • E.g., LDD moth, emerald ash borer

Fire management

• Surface fires burn undergrowth and leaf litter
  • Kill seedlings and small trees but mature trees survive
• Crown fires are hotter
  • Destroy most vegetative
  • Leap from treetop to treetop
• Ground fires
  • Burn peat and partially decomposed plant matter underground
  • Difficult to put out
• Many forest ecosystems depend on fire
  • Some seeds won't germinate without fire
  • Removes understory litter
  • So, fire suppression can be a problem
• Fire suppression changes the types of fire
• Prescribed burns can be a compromise
• Salvage logging?
• Housing developments
• Forestry = silviculture: try to balance managing forests as ecosystem and as sources of wood products
• Main player is canadian forest services
  • Multiple use policy: forests are to be managed for recreation, wildlife habitat, mineral extraction and various other uses
  • Ecosystem-based management: harvesting resources to minimize impact on the ecosystems and ecological processes
  • Adaptive management: systematically testing different management approaches to improve methods
    • Time-consuming, complicated, resistance to change

*recall

Ecologically extinct: not enough individuals to fulfill a species ecological role in a community

Commercially extinct: not enough individuals for commercials harvesting to be economically worthwhile

Extinct in the wild: but reared in zoos or as pets/ grown as a house or garden plant

How to estimate the current extinction rate

• Current extinction rate is hard to estimate because:
  • Extinctions can take a long time
  • We've only catalogued 1.4-1.8 million of an estimated 10-30 million extant species
• Approaches
  • Compare past and present extinction rates for well-documented species, e.g., mammals and birds
  • Infer from species area curves
• Human activity may also affect speciation rates and the types of species for which adaptive radiation take place

Biodiversity loss & species extinction

• Human arrival is generally associated with extinctions
• What species are most at risk of extinction?

Major causes of biodiversity loss

• Habitat alteration
  • Farming simplifies communities; monocultures
  • Grazing modifies grassland structure and species compositions
  • Clearing forests removes resources organisms need
  • Hydroelectric dams turn rivers into reservoirs upstream
  • Urbanization and suburban sprawl reduce natural communities
  • A few species (i.e., pigeons, rats) benefit from changing habitats
  • Causes:
    • Loss
      • Deforestation, especially of tropical forests
      • Wetland destruction
      • Loss of grasslands
• Fragmentation
  • Many small habitat patches don't equal one large habitat patch
  • Small, local populations can be vulnerable to extirpation
  • Cant support species with large home ranges
  • Ratio of edge to middle changes
  • Recall: island biogeography
• Invasive species
  • Causes:
    • Many introductions are deliberate
      • Important crop and livestock spp are often non-native
      • Introduced species are used for pest control
      • Other introduction are accidental
    • Introduced species may have
      • No natural predators, competitors, parasites, etc.
    • Not all introductions are successful and not all successfully introduced non native species become invasive
• Pollution
• Over harvesting
  • Causes:
    • Hunting, poaching and poorly-regulated harvesting
      • Especially if economic incentive increases with scarcity
• Climate change
  • Global impact on habitat and biodiversity
  • Modified global weather patterns and increases the frequency of extreme weather events stress pollutions
  • Force organisms to shift their geographic ranges
    • But that's not always possible
    • Or, ecosystems may not move fast enough
  • Some animals and plants will cope; others won't

Solutions: regulation

• International
  • International union for the conservation of nature
    • IUCN red list
      • Convention on international trade in endangered species (CITES)
        • International treaty restricting trade in endangered species
        • Appendix I species cannot be traded internationally
        • Appendix II species require a permit
• Canada
  • Committee on the status of endangered wildlife in canada (COSEWIC)
  • Species at risk act (SARA)

Solutions: sanctuaries

• Parks and wildlife reserves
  • Sometimes work but may be too small, in the wrong places, and created for a different purpose
  • Species at risk are often concentrated near human development
• Gene banks and seed banks
• Zoos, aquariums and botanical gardens
  • Great for education and entertainment
  • Limited success introducing species at risk back into the wild
  • Ethical issues

Poster species

• Umbrella species
  • Protecting habitat for one charismatic species indirectly helps the rest of the community or ecosystem
• Flagship species
  • Large, charismatic species used as the public face for conservation efforts

Solutions: reconciliation ecology

• Integrate wildlife and human habitat

Lakes and ponds (lentic)

• Oligotrophic lakes and ponds: low nutrient and high oxygen conditions (low productivity)
• Eutrophic lakes and ponds: have high nutrient and low oxygen conditions
• Eventually, water bodies can fill in through a process of succession
• Inland freshwater seas: large lakes that hold so much water, their biota is adapted to open water

Water diversion and withdrawal

• Diversions have altered river ecology
• Colorado river now often runs dry
• E.g., aral sea used to be fourth-largest lake on earth
• Lost over 80% of its volume in 45 years
  • 60,000 fishing jobs
  • Dust storms as sediment from the former lake bed is blown into the air

Dams and channelization

• Dam: an obstruction placed in a river or stream to block the flow of water so that water can be stored in a reservoir
  • Prevent floods, provide drinking water, allow irrigation, generate electricity
• Most major rivers have been damned
  • 45,000 large dams in > 140 nation
• Benefits:
  • Pqwoer generation
  • Emission reduction
  • Crop irrigation
  • Drinking water
  • Flood control
  • Shipping
  • New recreational opportunities
• Drawbacks:
  • Habitat alteration
  • Fisheries declines
  • Population displacement
  • Sediment capture
  • Disruption of flooding
  • Risk of failure
  • Lost recreational opportunities
• In the US, some dams are being decommissioned
• Restore riparian communities
• Reestablish populations of migratory fish
• Flooding is a normal process
  • Spread nutrient-rich sediments over large areas
• But, floods damage property
• Dikes and levees holds rising waters in channels
• Levees can make floods worse if/when they fail
• Channelization has also been important for transportation
• Other modifications include culverts, stream straightening (and burying)

Draining wetlands

• Is alo diversion
• Promote settlement and farming
• Wetlands were seen as useless swamps
• Now get some recognition of importance
• 1971 Ramsar Convention focuses on protecting globally significant wetlands

Irrigation

• Agriculture is the biggest consumptive user of water; that use is still increasing
  • Amount of irrigated land has doubled since 1960
  • Crop yields can double
• Irrigation can be really inefficient: 45% of water is absorbed by crops via “flood and furrow” irrigation
• Water mining= withdrawing groundwater faster than it can be replenished
• Groundwater is easily depleted because aquifers recharge slowly
• As aquifers become depleted
  • Water tables drop
  • Salt water intrudes in coastal areas
  • Some cities (e.g., mexico city) are slowly sinking
  • Wetlands dry up

Solutions

• pump/pipe.redirect water to where we needed it
• Desalination
• Use less water
  • More efficient irrigation
  • Math crops to climate
  • Personal choices
  • Market mechanisms

Water pollution

• Point source: discrete locations of pollution
  • Factory, sewer pipes
• Nonpoint source: pollution from multiple cumulative inputs over a large area
  • Farms, cities, streets
• Types: nutrient pollution, pathogens and waterborne diseases, toxic chemicals, sediment, thermal pollution

Nutrient pollution

• From fertilizers, farms, sewage, lawns, golf course
  • Leads to eutrophication
• Solutions
  • Phosphate-free detergents
  • Planting vegetation to increase nutrient uptake
  • Treat wastewater
  • Reduce fertilizer application
  • Recall macro and micro nutrients

Suspended sediments

• Sediment can impair aquatic ecosystems
  • Clear cutting, mining, poor cultivation practices
• Effects:
  • Dramatically changes aquatic habitats
  • Fish may not survive
• Solutions:
  • Better management of farms, forests and mining activity
  • Avoid large-scale disturbance of vegetation

Succession

• Used to think that succession led to a climax community
• Now view succession as more complex and influence by chance;maybe different climax communities are possible; maybe a mosaic of vegetation matches in a mature community

In the early 1800s, french start switching from jigging by hand to long lines (aka trawl lines, set lines)

• Requires lots of bait for lots of fish
• Up to 4-5 miles, with a hook every 3 ft
• Higher CPUE (catch per unit effort); efficient
• More capital intensive because of the bait
• Cant have too many dories or get tangles

In the early 1900s, the switch from sail to motorized ships allowed active fishing; outer trawl fleet starts

• Development of freezing leads to stern trawler factory fishing

Factory trawlers

• 1970s
  • USSR: 400
  • Japan: 125
  • Spain: 75
  • France and UK: 40
• Factory fleet caught as many cod in 15 years as all the cod that had been caught from 1497-1750
• Indiscriminate
• Fish 24/7 in any weather; impact on cod spawning
• CPUE, capital
• Fishing in late winter/early spring also disrupts spawning aggregations (mating: march-may)

In the 1970s-1980s Canada extended its authority with a 200 mile limit. The DFO also conducts its own surveys, but has to fight with other interest groups

• More regulation
• Government subsidies increases fisheries investment (bost construction; gear)
• 45% increase on canadian fisher 1977-1981
• Doubling of processing capacity

Commercial catch data unreliable

• High grading: keep the large fish and throw away the little ones to stay within quota
• Misreporting: avoid taxes by under reporting catch and selling some fish by privately on the side
• Bycatch: license is for haddock, but trawl is pulling up cod as well

80s-1992

• Late 1980s: quota cuts
  • 265,000 tonnes → 235,000 tonnes; protests
  • 1990: 190,000 tonnes
  • 1991: only caught 120,000 (couldn't meet quota)
  • 1992: fishery closed for the first time in 500 years
    • Moratorium was supposed to be 2 years
    • Affected 35,000 people directly
    • 40,000 indirectly
    • Many in smaller communities with limited employment options

Management

• Regional quote (total allowable catch; TAC)
• Limit the amount of fish that can be removed from an area; fishery is closed as soon as the TAC is reached
• Leads to a race to fish. Each fishers income depends on their catching as many fish as possible before the quote is reached
  • Over capitalization (bigger boats, better gear)
  • Temptation to fish in bad weather (safety)
  • Processing limitation = market glut
  • No incentive to conserve
  • E.g., halibut longlining

Individual transferable quota (ITQ)

• End the race to fish by allocating shares of the TAC to individual fishers or vessels
  • quotas/defined shares of catch
  • Allocated to individuals fishers or vessels
  • Transferable (buy, sell, lease, trade)
• Each fisher is responsible for keeping within their own quota, which keeps the fleet within its TAC
• Flexibility to schedule fishing around weather and market demand
• If you own the right to fish, the you have an incentive to maintain the value of the right (stewardship)
  • Vessel owners originally given their initial quota then stop fishing and rent the quota to someone else
  • Companies buy out the leases and fisherman become tenants
  • Vertically integrated fishery where the processing company owns the fishing licenses
• owners/operator solution: license owner must be on the boat
• Restrictions on processors bing licenses
• False sense of security
• ITQ is proportion of the TAC
• TAC can still go down depending on the amount of resources available
• Less incentive to over capitalize boats and gear, but strong incentive to over capitalize through cost of licenses
• Crew shares may decline because money is used to pay quota lease or purchase costs
• Excludes newcomers: if you were given a quota when ITQs were introduced then you're in great shape, but if you don't have shares than your excluded from the fishery

Community based management

• Community gets a quota; local community fishing board allocates it along community members
  • Individuals don't own anything directly, so it's easier for newcomers to enter the fishery

Adaptive management

• Set low quota for a fishery and then observe it closely
  • At sea observers

Other management considerations

• Bycatch
• Ghost nets
• Bottom trawls
• Fishing down the food chain
• Shifting baseline

Calculating how many fish there are

• Mark recapture method
  • # tagged the first time/ N
  • # recaptures/ total # 2nd captures
• Issues
  • Growth, mortality, immigration, emigration
  • Does tagging affect recapture?
    • Traphappy
    • Predation risk

Estimating reactive abundance to infer actually abundance

• Standardized surveys
• Catch per unit effort (CPUE)
• CREEL surveys

Maximum sustainable yield (msy)

• Maximum sustainable yield (msy) is the largest catch that can be taken from a species stock over an indefinite period
• Idea is to maintain the population at the level where it has its maximum growth rate
• limitations/risks
  • Simple version ignore size, age, and reproductive status
  • Doesn’t consider ecosystem impacts
  • Doesn’t consider bycatch

Climate

• Climate = long term atmospheric conditions in an area
  • Temperature, moisture content, wind, precipitation, etc.
• Weather = localized conditions over hours or days
• Global climate change = planet-wide trends
  • Temperature, precipitation, storm frequency
• Global warming
  • Refers specifically to temperature (just one aspect of climate change)
• Earth's climate has varied through time, but consensus that rapid changes taking place now are due to human activity

Three main determinants of global climate

• Sun
  • Supplies planets energy
• Atmosphere
  • Absorbs most incoming solar radiation (70%)
  • Reflects the rest (30%, albedo = ability to reflect sunlight)
• Oceans
  • Store and transport heat and moisture

Greenhouse gasses

• Earth's surface absorbs solar radiation and emits infrared
• Greenhouse gases are atmospheric gases that absorb infrared radiation (radiatively active gases) (water vapor is the most important GHG; its concentration hasn't changed)
• Greenhouse gases re-emit infrared energy
  • Some outward (to space)
• Some back down, warming the lower atmosphere and earths surface (greenhouse effect)

Carbon dioxide

• Anthropogenic greenhouse gas of primary concern
• Not the most potent greenhouse gas, but it is extremely abundant; major contributor to global warming
• Human activities have boosted atmospheric concentrations from 280 to 419 ppm (1750-2021)
• Human activities accelerate fluxes between reservoirs in biogeochemical cycles
  • Burning fossil fuels transfer CO2 from lithosphere (‘ground’) reservoirs into the atmosphere
  • Deforestation transfers CO2 from terrestrial reservoirs into the atmosphere
• Human-modified flux from lithosphere exceeds fluxes from atmosphere into carbon sinks
  • Oceans are the main sink
• Since 1750, 365 billion tonnes of carbon in CO2 released to the atmosphere
  • Mostly from the burning fossil fuels and making cement
• Canada is a significant contributor of CO2
• Clearing forests also releases CO2, especially mature forest
• Depletion is short-term if a forest is allowed to grow back, but not if the land is urbanized or used for agriculture
• Impact also depends on what's done with the wood

Methane and nitrous oxide

• Same pattern
• Note the scale on the y-axis
• Methane (CH4)
  • Fossil fuel deposits, livestock, landfills, some crops (rice)
• Nitrous oxide (N2O)
  • Feedlots, chemical manufacturing plants, auto emissions, synthetic nitrogen fertilizers
• Ozone
• Halocarbons (CFCs and HFCs)
• Water vapor
  • Most abundant greenhouse gas; contributes most to greenhouse effect

Estimating effects is messy

• Positive feedback cycles
  • Warming → evaporation → water vapor → more warming → more evaporation
  • Warming → oceans hold less CO2
• Negative feedback cycles
  • Warming → evaporation → more water vapor → cloudiness → reflects solar radiation
• Aerosols (microscopic droplets and particles
  • Black soot absorbs solar radiation
  • White aerosols reflects solar radiation

Radiative forcing

• Radiative forcing = the amount of change in energy that a given factor causes
  • Positive forcing warms the surface; negative forcing cools it
• Compared with the pre-industrial conditions, earth is experiencing radiative forcing of 1.6 watts/m2
  • Enough to alter the climate

Extra complications

• Variation in earth's rotation, solar output, ocean circulation

Proxy indicators

• Proxy indicators: types of indirect evidence that substitute for direct measurements
  • Trapped bubbles in cores from ice caps and glaciers

Direct sampling

• Present day data can be obtained directly
• Atmospheric CO2 has increased from 315 ppm to 419 ppm in 2021
• Seasonal variation is due to photosynthesis (more CO2 absorbed during northern summer)

Models

• Climate models simulate climate processes using information about
  • Atmospheric circulation
  • Ocean circulation
  • Interactions
  • Feedback mechanisms
  • Test models by entering data from the past and running the model to the present
  • Models that only include natural factors dont predicts observed climate trends; models including anthropogenic factors do

Trends and impacts

• Trend: a pattern that persists within a dataset after accounting for short-fluctuations and outliers
• Best summaries of the various datasets are produced by the intergovernmental panel on climate change (IPCC)
• 2021 IPCC sixth assessment report
  • Consensus of global scientific climate research
  • Trends in surface temperatures, precipitation, storms, snow and ice cover, etc
  • Evidence of climate change since industrialization is overwhelming
  • Impact will vary from place to place
• Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1 degrees celsius above 1850-1900 in 2011-2020
• Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred. Human caused climate change is already affecting many weather and climate extremes in every region across the globe. This has led to widespread adverse impacts and related losses and damages to nature and people (high confidence). Vulnerable communities who have historically contributed the least to current climate change are disproportionately affected (high confidence)
• Average surface temperatures have been rising since 1906; most of the increase has been in the last few decades (0.85 degrees)
• 1983-2012 was the warmest period of the last 1400 years
• Predicted increase of 0.7 degrees by 2035, and 1.5-3.0 degrees by 2100
• Changes in precipitation and storm activity will vary by region
  • Some regions receive more precipitation than previously; others receive less
  • Droughts have become more frequent and severe
  • Affects agriculture, soil erosion, drinking water supplies, forest fires
  • Heavy rains contribute to flooding
  • Maybe not # of storms, but intensity
• Temperature also becoming more variable, i.e., more extremes
• Increase in arctic temperatures weakens the polar jet stream
  • Meanders more
  • Atmospheric blocking patterns
• Melting ice and snow
  • Disappearing mountaintop glaciers
    • Risks of sudden floods as ice dams burst
    • Summer water supplies
  • Change in albedo: darker, less reflective surfaces are exposed and absorb more sunlight, causing more melting
  • Melting permafrost makes slopes unstable; may release soil gases leading to further warming
    • Also play havoc with building and road foundations
• Canada's arctic
  • Less snow cover
  • Melting ice sheets (greenland ice sheet)
  • Canada's ice shelves have shrunk by 90% over the past 100 years
  • Warming is accelerating as exposure of darker, less reflective surfaces reduces earth's capacity to reflect light
• Sea level
  • Sea levels rise as glaciers melt and water flows to oceans (15-35%)
  • Warmer water is less dense (30-55%)
  • Ice Sheet melting (20-27%)
  • Melting sea ice doesn't have a big effect
  • Effect of sea level varies from place to place
• Ecosystems
  • Modifies temperature dependant phenomena
    • Timing of migration, breeding
    • Mismatches between different seasonal patterns
  • Spatial shifts in the range of organisms (latitude or elevation)
    • IPCC estimates extinction risk for 20-30% of all species
  • Effect on plants as carbon sinks
  • Reefs: bleaching and ocean chemistry effects
• Social
  • Agriculture: longer growing season but rainfall shifts and mismatch between weather and soil
  • Forestry: growth vs. fire, drought, insect outbreaks
  • Health
  • Economic: less wealthy and more resource dependant are less able to adapt
• Cause
  • IPCC states that most global warming over the last 50 years is likely due to human activity (90% probability)
    • Primarily from increase in GHG from fossil fuels for energy and transportation
    • Also from land-use changes: forestry and agriculture

Options

• IPCC gives different predictions for different representative concentration pathways (RCPs)
  • I.e., different human responses and future GHG emissions
• Responses involve mitigation, adaption and intervention
• Mitigation: make changes that reduce GHG emissions, so that climate change is less severe
  • Renewable energy, different farming and forestry practice
• Adaptation: accept that climate change is happening; do things to minimize the impact
• Intervention: geoengineering - intentional, large scale modifications of global climate
  • Risky, because of unintended consequences
  • People are less likely to take mitigations steps

Mitigation

• Reduce consumption
• Use more efficient appliances
• Use different energy sources
• Carbon capture and storage: remove CO2 from power plant emissions
• Driving less and use public transportation
  • most effective way to conserve energy and reduce pollution
  • Live closer to your workplace, so you can bike or walk
• Automotive technology
  • Hybrid vehicles and EVs

Treaties

• International treaties haven't been very successful
• 1992
  • Unorganized voluntary agreement
  • By 2000. Reduce emissions to 1990 levels…no one did
• Kyoto protocol treaty
  • By 2012, reduce emissions to 1990 levels
  • US never ratified; canada pulled out in 2011
  • Didn’t require same restrictions for countries like china and india, so businesses in industrialized nations argued economic disadvantage
• 2015 paris agreement
  • Voluntary agreement to limit global warming to 2 degrees
  • US withdrew Nov. 2020… and rejoined Feb 2021
  • Norway: ban sales of gas and diesel cars by 2025

Market based tools

• Permit trading programs
  • Use free market to achieve policy goals
  • Chicago climate change was an emissions trading program for greenhouse gas reduction
• Cap-and-trade programs
  • European union emission trading scheme
• Carbon tax