Environmental Challenges & Population – Study Notes

For math, you need math; For physics, you need math; For chemistry, you need physics and math; For biology, you need chemistry, physics, and math; For earth science, you need biology, chemistry, physics, and math; For environmental science, you need earth science, biology, chemistry, physics, and math.
This slide highlights the interdependence of scientific disciplines and the foundational role of mathematics in understanding environmental issues.

Environment = all living and non-living things around us.
The Earth does not have the capacity to indefinitely absorb human impact and resource consumption at current growth rates (i.e., carrying capacity and sustainability concerns).

Central claim: Humans are the dominant agent of environmental change.
Implication: Human activities (consumption, production, pollution, habitat alteration) drive large-scale ecological shifts.

The central environmental problem is population size and growth over time.
Population timeline (conceptual from the slide):
- Population measured in billions, with a long growth history from the 18th century to present/future projections.
- Milestones illustrated: around the year 1800, global population reached approximately $10^9$ people; by 2015, it surpassed $7 imes 10^9$ .
The slide includes a growth curve from around 0.0–8.0 billions across years including 1750, 1800, 1850, 1900, 1950, 2000, and projections to 2050.

How many people Earth can support depends on sustainability practices.
The key message: carrying capacity is not fixed; it changes with technology, consumption patterns, and efficiency.

Population milestones:
- It took thousands of years to reach approx. $10^9$ around the year 1800.
- By 2015, the global population surpassed $7 imes 10^9$ .
Inequality between countries:
- MDC: Moderately Developed Countries — lower per person incomes, fewer opportunities (example: Mexico).
- LDC: Less Developed Countries — high population, low incomes, high infant mortality, disease, illiteracy (example: Haiti).
This section underscores the growing gap between richer and poorer nations and its relevance to global sustainability.

High rate of resource consumption in highly developed countries, often far exceeding basic survival needs.
Natural Resources: resources that are substances and energy sources from the environment that humans rely on for survival.

Resource classifications:
- Renewable natural resources
- Exhaustible renewable resources
- Non-renewable resources
Examples listed in the slide (noting that exact categorization may vary): Solar, Fresh water, Wind, Wave, Forest products, Biodiversity, Geothermal, Soil, Minerals, Natural gas, Coal.
Global equity in consumption (data excerpt from slide): Highly developed nations represent less than 20% of the world’s population but consume more than half of the world’s resources, including:
- $86\%$ of the aluminum used
- $76\%$ of timber harvested
- $68\%$ of energy produced
- $61\%$ of meat eaten
- $42\%$ of fresh water consumed

Definition: Ecological footprint is a way of measuring human impacts on the planet.
Distinctions:
- Ecological footprints can be considered per person for a given country (e.g., India, France, United States).
- They can also be considered in total for a country (the combined footprint of a population).

The Earth's ecological footprint has been increasing over time.
By the year 2010, humans were using the equivalent of $1.5$ Earths, a level that is not sustainable according to the slide.
This highlights a growing ecological overshoot and the need for changes in consumption, technology, and policy to move toward sustainability.

Interconnectedness of science: Mathematical literacy is foundational across disciplines when analyzing environmental issues (Slide 1).
Sustainability and limits: The carrying capacity concept (Slide 2) frames why overshoot (Slide 10) is a critical concern.
Human-driven change: Recognizing humans as the dominant agent (Slide 3) informs policy, ethics, and governance.
Population dynamics: Growth trends (Slide 4) and milestones (Slide 6) illustrate how demographic change interacts with resource availability and development disparities (MDC vs LDC).
Resource distribution and equity: A stark reminder that wealthier nations consume a majority of resources (Slide 8) even though they represent a minority of the population.
Ecological footprint as a diagnostic tool: Footprints (Slide 9) quantify pressure on biocapacity and help compare per-capita and total impacts across regions (Slide 10).
Ethical implications: The unequal burden of resource use and environmental degradation raises questions about equity, justice, and responsibilities of wealthier societies to poorer ones.
Practical implications: Emphasizes the need for sustainable practices, resource efficiency, and policies that reduce per-capita footprints to align with planetary boundaries.

Population milestones:
- Global population around year 1800: $ext{Population} \approx 10^9$
- Global population by 2015: \text{Population} \approx 7\times 10^9
Per-capita resource use indicators (illustrative):
- Aluminum usage: $86\%$ of world consumption attributed to highly developed nations
- Timber harvested: $76\%$
- Energy produced: $68\%$
- Meat eaten: $61\%$
- Fresh water consumed: $42\%$
Global footprint trend: $ext{Earths used by humans by 2010} = 1.5\ ext{Earths}$