Week 3 Notes – Ecological Footprint, Carbon Accounting & Sustainability

Week 3 structure
- Two separate video lectures this week
- Monday video (this one): Ecological Footprint fundamentals + overview of upcoming assignments
- Thursday video: Detailed walk-through of nutrient pollution and instructions for the SymBio assignment
Deadlines & platforms
- Canvas will list two deliverables for the week:
- “Ecological Footprint — Revised” document (download, complete, and re-upload)
- SymBio activity (opens after Thursday lecture; submission window ≈ 1 week, same model as first SymBio)
Support / communication
- Instructor encourages questions via email
- Reminder: one Thursday questionnaire item revisits the scientific method → students may need to reopen prior lecture slides
Holiday note
- Instructor wishes everyone a happy Memorial Day

Ecological Footprint (EF)
- A measure of the environmental impact an individual, population, or activity imposes on Earth
- Quantifies the biologically productive land & water required to
- produce all resources consumed, and
- assimilate / absorb all resulting waste (including CO₂)
- Units: global hectares (gha)
Global Hectare (gha)
- A standardized hectare whose productivity equals the average of all biologically productive hectares on Earth
- $1 \text{ gha} = 1 \text{ ha (with mean global productivity)}$
Hectare vs. Acre
- $1 \text{ ha} \approx 2.5 \text{ acres}$
- $1 \text{ ha} = 10{,}000\;m^2$
- Rough memory aid given in lecture: “a hectare is ≈ 2.5 times an acre”
Biocapacity
- The supply side counterpart to EF
- Amount of ecological resources Earth (or any region) can regenerate each year
- Influenced by changes in productivity per area or expansion/contraction of productive areas
Environmental-Footprint Standards
- Community-developed “best practices” so that all footprint assessments remain comparable across companies, products, and studies

Carbon Footprint (CF)
- Common shorthand expressing tons of (\text{CO}_2) emitted by an activity, organization, or product
How CF integrates into EF
- EF translates (\text{CO}_2) emissions into the hectares of forest or ocean needed to sequester that carbon
- Forests act as carbon sinks → trees absorb CO₂ for photosynthesis; thus, land area required to offset emissions is counted inside the overall EF
Take-home differentiation
- CF = “How many tons of carbon?”
- EF (carbon component) = “How much land/sea is needed to absorb that carbon?”
- CF is one slice of total EF

Average U.S. EF
- $\approx 10\;\text{gha per person}$
Planetary biocapacity per person
- $\approx 1.8\;\text{gha per person}$
Implication
- U.S. residents use > 5× the globally available biocapacity on a per-capita basis → ecological overshoot

Carrying Capacity ((K))
- Maximum population size an environment can support indefinitely
- Determined by available resources divided by consumption rate
Ecological Debtors vs. Creditors
- Debtors: regions whose EF > biocapacity → using more than local ecosystems can regenerate
- Creditors: regions whose EF < biocapacity → have surplus regenerative capacity
Satellite night-lights image
- Bright clusters = dense human populations
- Instructor’s ethical note: climate impacts often disproportionately burden sparsely populated / polar / developing regions that contributed least to the emissions

Equation introduced (letters noted as slightly ambiguous during lecture): $I = P \times A \times T$
- (I): total Impact (or “Input” in slide)
- (P): Population
- (A): Affluence (consumption per capita)
- (T): Technology (impact per unit of consumption)
Used to conceptualize how changes in any dimension scale overall ecological footprint

Multiple-choice prompt given live
- Correct answer: “Human society functioning in a way that is socially just and living within the means of natural systems”
Lecture definition
- “In a human-scale timeframe, the capacity to endure, thrive, and regenerate without over-burdening Earth’s living systems.”
Sustainable society
- Meets the needs of the present (all individuals) without compromising resources or opportunities for future generations
Rhetorical assignment teaser
- Students asked: “Are your present lifestyles sustainable?” → to be quantified in forthcoming worksheet

Document components
1. Table to log personal consumption & land-use categories
2. Reflective questions on lifestyle sustainability
3. Follow-up questions demanding application of earlier “scientific method” material
Submission tips
- Ensure every field is completed; partial sheets = incomplete
- Link available in Canvas instructions; upload finished PDF/Word as directed

Topic: Nutrient pollution (nitrogen, phosphorus, eutrophication, etc.)
SymBio platform
- Interactive online simulation; will replicate first-week SymBio workflow
- Opens post-lecture; due 1 week later
- Canvas will also host a short graded assignment paralleling the SymBio activity

Disparity in climate impacts
- Populous, affluent regions drive emissions but often avoid worst consequences
- Vulnerable: polar communities, small-island states, and low-emission developing countries
Practical implication
- Emphasizes justice component within sustainability; policies must account for unequal exposure to harm

Review definitions: EF, biocapacity, CF, global hectare, carrying capacity, IPAT
Compare personal EF against 1.8 gha planetary capacity
Finish readings before Thursday; consult scientific-method slides if rusty
Complete both Canvas deliverables; email with questions
Enjoy Memorial Day while keeping sustainability concepts in mind