Physical Anthropology: Exam 2

Global Population Milestone

Hit 8 billion in 2022; projected to reach 10 billion by 2057.

Consequences of Population Growth

Resource depletion (food, water, energy), increased pollution and greenhouse gases, rapid urbanization with infrastructure strain.

Megacities

Extremely large cities with populations over 10 million; struggle with infrastructure, disease control, and resource management.

Urbanization Trend

More people moving from rural areas into cities; by 2050, about 70% of humans will live in urban areas.

Habitat Loss

The #1 cause of species extinction; occurs when humans destroy natural environments for farming, housing, mining, and development.

Biodiversity Loss

Reduction in variety of life on Earth; we're currently in Earth's 6th mass extinction event, caused by humans.

Ecosystem Services

Natural processes that benefit humans (Examples: bees pollinating crops, forests filtering water, wetlands controlling floods, oceans absorbing CO2).

Why Biodiversity Matters

When we lose species, we lose ecosystem services; damages the natural systems that human survival depends on.

The Anthropocene Era

A new geological era where human activity is the dominant influence on planet's climate and environment; 'Age of Humans.'

Activities Defining the Anthropocene

Industrialization, nuclear testing, plastic pollution, massive fossil fuel burning that changed atmospheric and ocean chemistry.

The 3 Types of Fossil Fuels

1. Solid (Coal), 2. Liquid (Petroleum/Oil/Gasoline), 3. Gas (Natural Gas/Methane)

Why Called 'Fossil' Fuels?

Made from remains of ancient plants and animals that were buried and compressed millions of years ago.

Coal Formation

Ancient plants buried in swamps → compressed over millions of years → turned into coal (solid carbon).

Petroleum Formation

Ancient marine organisms buried → heat and pressure over millions of years → turned into oil and natural gas.

Fossil Fuel Combustion Chemistry

When burned, carbon in fuel combines with oxygen from air → produces CO2 (carbon dioxide) and releases energy.

Gas to CO2 Weight Ratio

1 pound of gasoline creates 3.2 pounds of CO2 (6 lbs gas = 19.2 lbs CO2); weight increases because carbon combines with oxygen.

Methane (CH4)

An 'even worse' greenhouse gas than CO2; much more powerful at trapping heat in atmosphere (about 25-80x more potent).

The 3 Main Sources of Methane

1. Livestock (enteric fermentation - cow burps/gas), 2. Landfills (rotting garbage), 3. Fossil fuel extraction (leaks from gas wells and coal mines)

Enteric Fermentation

Digestive process in ruminant animals (cows, sheep) that produces methane; released through burps and flatulence.

Livestock and Climate Change

Animal agriculture, especially cattle, is major methane source; produces more greenhouse gases than all transportation combined.

Landfill Methane

Organic waste decomposing without oxygen in landfills releases methane; can be captured and used for energy.

'Consuming Earth's Capital'

We're using up natural resources (forests, fossil fuels, aquifers) rather than living off renewable 'interest'; unsustainable.

Feedback Loop - Climate

Melting glaciers and permafrost release more greenhouse gases → causes more warming → causes more melting; self-accelerating process.

Permafrost Melting Danger

Frozen soil in Arctic contains massive amounts of trapped methane and CO2; as it melts, releases these gases, accelerating warming.

The 6 Intersecting Global Threats

1. Population growth, 2. Rising temperatures, 3. Falling water tables, 4. Ocean acidification, 5. Saltwater intrusion, 6. Food shortages

Population Growth Threat

More mouths to feed with limited resources; puts pressure on food production, water supplies, and ecosystems.

Rising Temperatures Threat

Changes where and what crops can be grown; increases extreme weather events; disrupts traditional farming.

Falling Water Tables

Pumping groundwater out of aquifers faster than rain can refill them; eventually leads to wells running dry.

Aquifer Depletion

Underground water reserves being drained; some aquifers took thousands of years to fill but are being emptied in decades.

Ocean Acidification

Oceans absorb CO2 from atmosphere → forms carbonic acid → makes ocean water more acidic → kills coral reefs and shellfish.

Why Ocean Acidification Matters

Coral reefs support 25% of marine species; shellfish with calcium carbonate shells dissolve in acidic water; disrupts marine food chains.

Saltwater Intrusion

As sea levels rise, salt water leaks into fresh groundwater near coasts; makes water undrinkable and soil unfarmable.

Food Shortage Threat

All the other 5 factors (population, temperature, water, acidification, saltwater) combine to make farming unpredictable and reduce yields.

Strategy: Stabilizing Population

Improving education (especially for women) and healthcare; educated women have fewer, healthier children.

Strategy: Conservation

Protecting 30% of planet's land and water from development; preserving biodiversity and ecosystem services.

30x30 Goal

Protect 30% of Earth's land and oceans by 2030; international conservation target.

Strategy: Sustainable Agriculture

Using 'precision farming' techniques to save water and soil; crop rotation, reduced tillage, targeted fertilizer use.

Wind Energy

Turbines convert kinetic energy from wind into electricity; renewable, no emissions during operation.

Solar Energy - Passive

Designing buildings to naturally catch and store sun's heat; uses architecture rather than technology (large south-facing windows, thermal mass).

Solar Energy - Photovoltaic (PV)

Solar panels that convert sunlight directly into electricity using semiconductor materials.

Hydroelectric Energy

Using dams on rivers to capture energy from falling water; most established renewable energy source.

Ocean Energy

Using movement of tides and waves to generate electricity; consistent and predictable energy source.

Geothermal Energy - Vents

Using heat from deep volcanic areas to generate steam for electricity; common in Iceland, New Zealand, parts of California.

Geothermal Energy - Residential

Using steady temperature of ground just a few feet down to heat/cool homes; ground is warmer than air in winter, cooler in summer.

Ground Source Heat Pumps

Geothermal system that moves heat between house and ground; extremely efficient for heating and cooling.

Biofuels (Plant Alcohols)

Turning corn, sugar cane, or algae into ethanol to use as fuel; renewable but requires land and water.

Ethanol

Alcohol fuel made from fermenting plant sugars; can be mixed with gasoline or used alone in modified engines.

5 Renewable Energy Technologies

1. Wind, 2. Solar (passive & PV), 3. Water/Hydro, 4. Geothermal, 5. Plant Alcohols/Biofuels

Why Renewables Matter

Don't produce greenhouse gases during operation; won't run out like fossil fuels; reduce air pollution.

Carbon Footprint

The total amount of greenhouse gases produced by human activities; measured in tons of CO2 equivalent.

Greenhouse Effect

Certain gases trap heat in atmosphere like glass in a greenhouse; natural process that makes Earth habitable, but excess causes warming.

Enhanced Greenhouse Effect

Human activities have increased greenhouse gas concentrations, trapping more heat than natural levels; causes global warming.

Paris Climate Agreement

International treaty where countries agreed to limit global temperature rise to below 2°C; requires reducing emissions.

Renewable vs. Nonrenewable Resources

Renewable = can be replenished naturally (sun, wind, trees if managed); Nonrenewable = finite supply (fossil fuels, minerals).

Tragedy of the Commons

When shared resources (oceans, atmosphere, forests) are overexploited because individuals benefit from use but share costs of depletion.

Sustainable Development

Meeting current needs without compromising ability of future generations to meet their needs; balancing economy, environment, society.

Precision Agriculture

Using GPS, sensors, and data analysis to apply exact amounts of water, fertilizer, and pesticides only where needed; reduces waste and environmental impact.

Water Table

The upper surface of underground water (aquifer); level drops when we pump out water faster than rain replenishes it.

Why 'Human Disconnect'?

Humans have become disconnected from natural systems that sustain us; modern lifestyle obscures where food, water, energy come from and impact of our consumption.