South AmericaEnvironmental Geography

• Introduction & Rural environmental issues

1

• Urban environmental challenges2

• Western mountains & Eastern shields3

• River basins & Lowlands4

• Climate patterns5

• Latin America & Global warming6

Challenge to S.A. goverments

The need for economic

development

The need for environmental conservation

Rural environmental issuesDeclining forests & Degraded farmlands

Deforestation & Biological

loss

Agriculture

Wood export

Search for gold

Permanent settlement

Grassification

▪ Definition: The conversion of tropical forest into pasture

▪ A practice that contribute to forest loss

▪ In Southern Mexico, Central America, Brazillian Amzon, development policies encouraged deforestation to make room for cattle

▪ However, ranching in remote areas is seldom economically self-sustaining

Problems on Agricultural lands

Pressure to modernize agriculture causes many environmental problems

▪ Adopting new hybrid species of corn, beans, etc -> native species disappearance -> genetic diversity erosion

▪ Chemical fertilizers & pesticides -> contaminating soil & water; causing severe health issues

▪ Failure/lack of soil conservation measures -> soil erosion & fertility decline -> production decreased

▪ Urban expansion claims much of the best farmlands

Urban environmental challenges

▪ Latin America’s most pressing environmental issues are found in its urban areas

▪ Mexico City is a good example of the kinds of environmental challenges facing modern Latin American cities

A picture of Mexico City taken by BBC

I. The Valley of Mexico’s Environmental Problems

The Valley of Mexico

▪ Cradle of Aztec civilization

▪ Site of Mexico city with a pop. of 18 mil people

▪ Has the ideal environmental settings to build a city, though it’s currently severely degraded

Mexico City’s most pressing problems

▪ Air quality

▪ Water pollution

▪ Subsidence (soil sinkage)

1. Air Quality

▪ A major issue since the 1960s

▪ Caused by city growth, number of cars & physical settings

▪ Pollution high enough to cause a gray cloud hanging above the city

The city’s settings play a major role in creating pollution and enlarging it

▪ The city sits in a bowl 2250 meters above sea level

▪ A layer of warm air traps a layer of cold air near the surface (thermal/temperature inversion)

▪ The cold air layer is filled with pollutants

▪ Cause a great deal of troubles for the inhabitants

Steps taken to improve the situation

Starting from 1980s: reduce emissions from factories and cars

▪ Unleaded gas available for the 4mil cars in the metropolitan areas

▪ Cars for Mexican markets must have catalytic converters

▪ Worst polluting factories closed

▪ Program restricting driving was expanded

▪ Expanded low-emission Metrobus system, build suburban train system

=> No longer ranks in the top polluted cities in the world, cut pollutants by half

2. Water Pollution

▪ One of the most relentless environmental problems

▪ Most water – which used to fill the valley in lakes – were drained for agriculture

▪ Less surface water => more wells were dug to use the basin’s fresh water aquifer

▪ Evidenced that the aquifer is being overdrawn and at risk of contamination

▪ To reduce reliance on underground water, the city pumps water from 160km away

3. Subsidence (soil sinkage)

▪ Mexico is sinking, as the metropolis pumps water from its aquifer

▪ Impacted the whole city throughout:

- Building foundations destroyed

- Water and sewer lines rupture

- Damaged landmarks

▪ Water no longer being pumped from the city => slowed the sinking to 2.5cm a year compared to 50cm at its worst

Impact of sinkage

The Cathedral leaning to the left after centuries of subsidence

Cracks in building foundations

II. Ongoing Urban Challenges and Responses

▪ For most Latin Americans, most pressing environmental problems = air pollution, inadequate water and garbage removal

▪ They live better than their counterparts in Asia and Africa but still need expensive remedies for env. problems

A squatter settlement in Mexico City

Industrialization = major cause for pollution, but government tends to go easy on enforcing env. laws

=> in the worst cases, it poses a serious threat to people and the environment

Cubatão, São Paulo, Brazil, once called the valley of death due to pollution

▪ Not far from Cubatão is Curitiba, the capital of Paraná state – a model city also called the “Green City” for its planning decisions

▪ Significantly less polluted than other similar sized cities

▪ City planners built drainage, canals for floodings, set aside other areas as parks early during the 1960s

▪ Public transportation = top priority

▪ Low tech but effective recycling program

=> Designing with nature makes sense both ecologically and economically

Curitiba City, Brazil

Western Mountains and Eastern Shields

▪ The Andes

▪ Relatively young, 5,000 miles long; 30 peaks over 20K feet

▪ Active volcanism and earthquake

▪ Contain valuable metals and minerals

Western Mountains and Eastern Shields

▪ The Andes is divided into northern, central and southern component.▪ The northern Andes: 3

mountains ranges

Western Mountains and Eastern Shields

Altiplano: treeless, elevated plain in Peru and Bolivia, the floor ranges from 11,800 feet to 13,000 feet

Two high-altitude lakes: Lake Titicaca and Poopó

Western Mountains and Eastern Shields

▪ The southern Andes: the highest peaks, Aconcagua, 23,000 feet, mountains are lower

Western Mountains and Eastern Shields

The Uplands of Mexico and Central America

▪ The Mexican Plateau and the Volcanic Axis of Central America: The most important Latin America uplands

▪ Most major cities and population found her

Mexico City

Guadalajara Puebla

Western Mountains and Eastern Shields

▪ Rich volcanic soils, domestic and export crops

▪ Agriculture land that yield beef, cotton and coffee

Western Mountains and Eastern Shields

▪ The Shields: 3 major shields▪ The Guiana shield

▪ The Brazilian shield: the largest shield, more important,rich of fertile red soils, elevated basins ( city of São Paulo-largest urban conglomeration in SA), commercial agriculture

Western Mountains and Eastern Shields

▪ The low-lying Patagonian shield: treeless, covered by scrubby steppe vegetation, offshore oil production

River Basin and Lowlands

Within these basins are vast interior lowlands:

▪ The Llanos

▪ The Amazon lowlands

▪ The Pantanal

▪ The Chaco

▪ The Pampas

Settlement

Natural resources

Intense economic activities

Amazon Basin

▪ Geography:

- The largest river system in the world by volume and area, the second longest by length (2.4 million square miles)

- There is no real dry season

The Amazon

contributes 20% of

all freshwater

discharged into

the ocean.

Amazon Basin

▪ Amazon Basin draws from 8 countries

An ideal network to integrate the northern half of South America

Population

▪ Most of the older settlements are found on the floodplain, where natural levees reach heights of 20 feet (6 meters)

▪ Roughly 15m people (about 8% of the country’s total population) live in Brazilian Amazon

PLATA BASIN

▪ The region’s second largest watershed

▪ Make up from 3 major rivers:

+ The Parana

+ The Paraguay

+ The Uruguay.

▪Economically productive:

especially soybean production

The Chaco (arid area)

The Pantanal

(inundated lowlands)

Support livestock

Contains major dams: Itaipu - region’s largest hydroelectric plant

-Enhance Panara River’s capacity for barge and boat traffic.

Orinoco Basin

▪ The third largest river basin

▪ Located in northern South America

Population

North of the basin: 90% of Venezuela’s population

The Industrial developments between Ciudad Guayana and Ciudad Bolivar:

many cities located.

Llanos (grasslands)

▪ Support large cattle ranches

▪ Become a dynamic area of petroleum

production for Colombia and

Venezuela.

Climate patterns

In tropical Latin America averagemonthly temperatures show littlevariation. Precipitation pattern dovary, however, and create distinctwet and dry seasons.

▪ The tropicallowlands classifiedas tropical humidclimates thatsupport forest orsavanna, dependingon the amount ofrainfall.

▪ Extreme aridity region’s desert climates

▪ Midlatitude climates, with hot summers and coldwinters, prevail in Argentina, Uruguay, and parts ofParaguay and Chile.

The Andean range over the province of Santa Cruz – Argentina.

Altitudinal Zonation

▪ Altitudinal zonation has practical applications.

▪ The environmental lapse rate.

The concept of altitudinal zonation is most relevant for the Andes, the highlands of Central America, and the Mexican Plateau.

El Nino

▪ Occurs when a warm Pacific current arrives along thecold coastal waters of Ecuador and Peru in December,around Christmastime

▪ Happens every few years

▪ Produces torrential rains, signaling the arrival of an ElNino year

▪ El Nino’s impacts.

Global Warming

Global warming - one of the dominant issues in Latin America

8% of the world’s population

▪ 6-8% of global greenhouse emissions

▪ Rate of greenhouse emissions growth : lower than in all other regions, except for Sub-saharanAfrica

Reasons for low greenhouse emissions growth rate

▪ Lower average energy consumption

▪ Higher reliance on renewable energy

▪ Greater dependence upon public transportation

Highland areas :Higher temperature and Lower rainfall

Retreat of Andean glaciers

Retreat of Andean glaciers

Dengue fever

Dengue is now widespread in more than 100 tropical and sub-tropical around the world

• Impact the frequency and strength of El Nino cycles => Increased flooding in Western South America=> Declining fishery off the coast of Peru and Chile

• Increasing hurricane intensity

Several unprecedented weather-related events in the recent past

• Intense rainfall in Venezuela (1999, 2005)• Amazon drought (2005) in Brazil• Hailstorms in Bolivia (2002) and Greater

Buenos Aires area (2006)• The devastating hurricane Katrina in 2004

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