Geography midterm

Ecosystem

A system of living organisms interacting with each other and their physical environment.

Earth as a life-supporting planet

Earth is the only known planet that supports life and receives energy from the Sun.

Current extinction crisis

Species are becoming extinct at rates not seen over the past 65 million years.

Main causes of extinction in the notes

Climate change, pollution, and abrupt human-caused environmental change.

Human impact on environmental change

Human activities often make environmental changes faster and more severe than natural processes would.

Environmental change

The environment is always changing through natural processes such as rain, sunlight, and natural disasters.

Population growth as an ecosystem pressure

A growing human population increases demand for global resources.

Consumption as an ecosystem pressure

Increasing use of global resources places additional pressure on the environment.

Changing values and behaviours

Changes in values, expectations, perceptions, and attitudes can change human behaviours toward the environment.

Long-term view

Environmental planning over more than 15 years.

Mid-term view

Environmental planning over 5–15 years.

Short-term view

Environmental planning over less than 5 years.

Why environmental problems need long-term planning

Problems may take decades to develop and decades to clean up; there is rarely a quick fix.

Environmental trade-offs

Environmental change can create winners and losers, and may also create opportunities.

Ecological benefits of fire

Fire releases nutrients, encourages plant growth, increases decomposition, and supports herbivores and carnivores.

How fire affects forest soils

Fire removes shade, raises soil temperature, and can increase microbial activity and decomposition.

How intense fires can change vegetation

Intense fires can replace trees with grasses and shrubs.

Lodgepole pine adaptation

Heat can release seeds from lodgepole pine cones.

Human uses of fire

Hunting, clearing land for agriculture, and controlling insects and diseases.

Risk of frequent fires

deplete soil nutrients and prevent trees from growing.

Controlled burns

Planned fires used to mimic natural fire and help maintain healthy ecosystems.

When Canadian forest fires are most likely

Between snowmelt and leaf opening, when the ground is warm, dry, and less shaded.

Climate change and wildfires

Climate change can lengthen the fire season and increase fire intensity.

Smoke transport from western Canadian fires

The jet stream can carry fire pollution toward the Atlantic coast.

Health effects of wildfire smoke

Headache, nausea, drowsiness, confusion, death, and increased respiratory and cardiovascular hospital admissions.

Wildfire management

Deciding which fires to let burn and which to contain.

Factors in wildfire management

Species affected, infrastructure, cultural values, smoke, suppression costs, weather, and long-term effects.

Wicked problem

A difficult social, cultural, or policy challenge with incomplete, contradictory, or changing requirements.

Why wildfires are a wicked problem

They are difficult to define, involve stakeholders with different values, and solutions can create new problems.

Big Bang theory

The theory that a massive explosion about 14 billion years ago created the universe.

Age of Earth

Earth formed about 4.6 billion years ago.

Early conditions on Earth

Rocks, oceans, and an atmosphere formed; precipitation helped create a nutrient-rich environment.

First life

bacteria and unicellular life appeared about 3.8 billion years ago.

Early life in the oceans

Early life developed in the ocean because ultraviolet radiation made land dangerous.

Photosynthetic bacteria

About 2.5 billion years ago, they removed methane and added oxygen to the atmosphere.

Ozone layer development

Oxygen in the atmosphere enabled formation of an ozone layer that helped protect life from UV radiation.

First reptiles

Appeared about 308 million years ago and depended on external temperatures.

Mesozoic Era

About 245–65.5 million years ago; known as the age of reptiles, especially dinosaurs.

Dinosaur extinction

Dinosaurs became extinct about 65.5 million years ago after an asteroid impact and major atmospheric cooling.

Rise of mammals

Mammals could regulate their body temperature and expand into a wider range of climates.

Cenozoic Era

The period after 65.5 million years ago, when Earth developed many features of its modern form and large mammals appeared.

First hominids

Ancestors of humans that could walk upright; appeared about 5.4 million years ago

Past mass extinctions

The notes describe five periods when changing carbon dioxide levels, oxygen levels, volcanism, and glaciation caused major losses of life.

Plate tectonics and climate

Movement of land masses changes ocean currents and can contribute to climate change.

Pangaea

The single landmass from which Earth's continents gradually split apart.

Homo ergaster

An early human species that used stone tools and lived in Africa and Europe about 1.8–1.4 million years ago.

Homo erectus

An early human relative that migrated from Africa into Asia and used fire for cooking.

Homo antecessor

An early human species that lived in Africa and Europe and developed primitive speech patterns, according to the notes.

Homo neanderthalensis

A human species that lived roughly 400,000 to 10,000 years ago and may have interbred with Homo sapiens.

Homo sapiens

Modern humans, present for about 200,000 years and the only surviving hominid species.

Human evolutionary advantage

A relatively large brain-to-body ratio helped hominids adapt to new environments as they migrated.

Human migration out of Africa

Humans spread to the Middle East, Australia, China, and eventually North America via the Bering land bridge.

Bering land bridge

A land route exposed by lower sea levels during the last ice age that allowed migration into North America.

Hunter-gatherer societies

Societies relying on wild foods, with limited food supplies and relatively low life expectancy.

Pre-agricultural population

Human population was relatively stable at about 6 million before 12,000 years ago, according to the notes.

Agricultural Revolution

Domestication of plants and animals beginning around 10,000 years ago, increasing and stabilizing food supplies.

Effect of agriculture on population

More reliable food supplies helped increase birth rates and population.

Population around 2,000 years ago

250 million.

Energy before the Industrial Revolution

People relied on recently produced energy from humans, animals, wind, water, and wood.

Industrial Revolution and population growth

Coal-powered technology greatly increased available energy and food production.

Second Agricultural Revolution

Mechanization, including steam engines on farms, increased the amount of food that could be produced.

World population in 1804

1 billion.

World population in 1927

2 billion.

World population in 1973

4 billion.

World population in 1987

5 billion.

World population in 1999

6 billion.

World population in 2026

About 8.3 billion, according to the notes.

Projected world population in 2050

About 9.6 billion

Projected world population in 2100

About 10.9 billion

Rate of natural increase

Crude birth rate minus crude death rate, usually measured per 1,000 people.

Crude birth rate

Number of births per 1,000 people in a year.

Crude death rate

Number of deaths per 1,000 people in a year.

Thomas Malthus

Thinker who predicted population would grow exponentially while food supply grew arithmetically, leading to famine, disease, and war.

Why Malthus's predicted crisis was delayed

New farmland in the Americas and Australia, followed by the Green Revolution, increased food supply.

Neo-Malthusians

People concerned that population growth may exceed food and resource availability.

Green Revolution

Agricultural changes in the 1950s and 1960s that greatly increased food production.

Millennium Ecosystem Assessment

Assessment by about 1,360 experts from 95 countries that reported rapid environmental degradation.

Anthropocene

Proposed epoch describing the significant influence of human activity on Earth, with markers appearing after about 1750.

Evidence used to identify the Anthropocene

Fossil-fuel fly ash, new materials such as concrete and plastic, and sea-level changes.

Fertility rate

Average number of children a woman has during her childbearing years.

Replacement fertility

About two children per couple on average, allowing a population to replace itself over time.

Factors associated with lower fertility

Later marriage and childbearing, and greater access to education for women.

Population pyramid

A bar graph showing population by age groups, typically with males on the left and females on the right.

Effects of high birth rates

A large young population increases demand for childcare, education, and jobs.

Effects of low birth rates

A larger proportion of older people can create labour shortages and increased retirement-care needs.

Zero population growth

A state where population size remains stable overall.

Below-replacement fertility

Fertility below the level needed for a population to replace itself without migration.

Demographic transition Stage I

High birth and death rates; population is relatively stable with little growth.

Demographic transition Stage II

Death rates fall while birth rates remain high, causing rapid population growth.

Demographic transition Stage III

Birth rates fall, slowing population growth.

Demographic transition Stage IV

Low birth and death rates; population is large and relatively stable.

Demographic transition Stage V

Death rates exceed birth rates, so population declines.

Epidemiological transition

Long-term decline in death rates as sanitation, vaccines, infectious-disease knowledge, antibiotics, and nutrition improve.

Why birth rates fell after industrialization

Children became less needed as labour as machinery, paid labour, and consumption changed family economics.

Population trends in developed countries

Slow growth or no growth, with increasing life expectancy.

Population trends in developing countries

More rapid population growth

Kuznets Curve

Idea that environmental damage rises during development, then may decline when wealth allows environmental protection; it does not apply to every situation.

Migration

Permanent movement to a new location; it changes where people live but not the total world population.

Emigration

Leaving a country to live elsewhere.

Immigration

Entering a country from another country.