Contemporary Global Environmental Issues L5-L8

These flashcards cover key vocabulary and concepts from the lecture on contemporary global environmental issues, focusing on climate change, ecosystem interactions, pollution, urbanization, and demographic impacts.

Response Time

time it takes for the climate system to adjust to a change in forcing, 50% of the way towards equilibrium

Positve feedback example

water vapour → increased climate change→ increased water vapour

El Niño

unusual warming of sea surface waters in the east central tropical Pacific Ocean

- Peaks around Christmas Season –

“ Christ Child” “ The Boy”

- occur about every 2-7 years → evolution: develops in late spring/ early summer

peaks around Chirstams and decay in the spring

- first found unusually active in the late 20th century compared to past 700 years

La Niña

- opposite phase of El Nino – unusual cooling of sea surface in the east

- Snowstorms events even if not that cold (?)

- “The girl”

Monsoon

the seasonal reversal of wind direction associated with large continents especially

Asia

- Summer: wind blows from ocean to land

- Winer: wind blows from land to ocean

Monsoon Formation Mechanism

1. Land Sea differences:

- (1) land and water have different heating capacity

- (2) water can store more heat because it is a fluid and can mix heat down for

future release

- 2. Planetary rotation:

- introduces swirl and much stronger winds

- does not generate wind only modifies airflow and speed

- 3. Moisture:

- water vapor, collected over oceans through evaporation condenses over

land and marginal seas releasing vast quantities of heat

- 4. Orography: acts as elevated heat source which intensifies flow and also ducts

flow

Point Source Pollution

Pollution that originates from distinct, identifiable, and localized sources

Examples include discharge pipes from factories, wastewater treatment plants

Non-point Source Pollution

Pollution that comes from diffuse, scattered, and often multiple sources over a broad area, making it difficult to pinpoint a single origin.

Examples include agricultural runoff containing pesticides and fertilizers, urban stormwater runoff, or sediment from construction sites.

Demographic Transition

- transition stages:

1. Preindustrial (high death rate + high birth rate; population low)

2.Transitional (death rate decrease; population grows rapidly)

3. Industrial (birth rate decrease; population growth slow )

4. Postindustrial (birth rate + death rate remain low and stable; population levels off then fall down)

Urban Heat Island

A phenomenon where metropolitan areas experience significantly higher temperatures than their surrounding rural areas.

absorption of solar radiation by dark paved surfaces, reduced vegetation, waste heat from buildings and vehicles

Greenhouse Gas (GHG)

Any gas in the atmosphere that absorbs and emits infrared radiation, thereby trapping heat and contributing to the greenhouse effect which warms the Earth's surface. Major GHGs include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor (H2O).

Advantages of Groundwater Withdrawal

Groundwater withdrawal provides a reliable source of fresh water for irrigation, drinking, and industrial uses, especially in arid regions or during droughts. It is often less susceptible to surface pollution and evaporation compared to surface water sources.

Disadvantages of Groundwater Withdrawal

aquifer depletion, land subsidence (sinking of land), saltwater intrusion in coastal areas, increased pumping costs, and reduced baseflow to rivers and wetlands, impacting ecosystems.

Advantages of Dams

Dams provide multiple benefits such as hydroelectric power generation (clean energy), flood control, irrigation water supply, municipal water supply, and recreational opportunities.

Disadvantages of Dams

displacement of communities, alteration of river ecosystems (e.g., blocking fish migration, changing sediment flow), loss of biodiversity, disruption of natural flood cycles, and potential for dam failure leading to catastrophic flooding.

Adaptation

Adaptation refers to the strategies and measures implemented to adjust to ecological changes caused by climate change

Mitigation

A set of actions and policies undertaken to reduce or prevent the emission of greenhouse gases (GHGs)

Negative feedback example

Cloud radiative feedback

Why polar regions temperature increase so rapidly, more so than other regions?

- Albedo decrease caused by sea ice melting

- Heat transport from the tropics

- Heat accumulates on surface no strong downward transport in ocean

Emission scenarios

- Population growth

- Economic growth

- Sources of energy generation

- Energy use efficiency

Change of temperature due to climate change

likely (90%) to exceed 1.5 degree, unlikely (10%) to exceed 4 degree

Greatest warming over land & Least warming over Ocean

Water availability data

→ 70% of the Earth is covered by water BUT

→ only 2.4 % freshwater

→ only 13% of freshwater is liquid water

→ only 0.02% is readily available for human us

Driving forces and pressure on water resources

Population growth particularly in water short regions (most fundamental)

- Urbanization

- higher water consumption per capita; per unit area

- Higher standard of living

- Increased competition between users and usages

- eg. agricultural(67%) vs industrial(~20%) vs domestic(~10%)

- Climate change (the wet get wetter, the dry get drier)

-pollution

How forests can prevent flooding

- tree roots stabilize soil and aid water flow

- vegetation releases water slowly and reduces flooding

- Tree reduce soil erosion from heavy rain and wind

- steady evapotranspiration→ reduce the amount of water for runoff

How wetland prevent flooding

 -provide natural flood and erosion control

- maintain high water quality→ natural filter

- recharge groundwater→ allow the excess water to slowly penetrate

What affect demograohy?

APPS

-age structure

-population size

-population density

-sex ratio

Four major trends of urbanization

1. Proportion of global population living in urban areas is increasing

- 2. Number and size of urban areas are mushrooming

- Megacities (10-20 mil) Hypercities (20-40 mil)

- 3. Urban growth has slowed in developed countries

- 4. Poverty is becoming urbanized, mostly in less-developed countries