Fragile environments

Define a Fragile environment:

• Fragile environments are vulnerable/sensitive to change AND will struggle to recover (2)

4 examples of fragile environments:

Arid and semi-arid environments

Tropical rainforests 

Cold environments

Coral reefs

What is desertification?

The spread of desert like conditions into semi- arid areas

State 3 natural causes of soil erorion:

• Soil erosion

• Rainfall patterns

• Reduced vegetation

How does soil erosion cause desertification:

Soil erosion (movement of top soil) leads to the loss of nutrients. Plants are unable to establish and grow

How do Rainfall patterns cause soil erosion?

Rainfall patterns have become less predictable leading to drought and any vegetation dying due to lack of water

How does reduced vegetation cause soil erosion?

Reduced vegetation means that nutrients are not added to the soil through the decomposition of dead organic matter

State 4 human causes of desertification:

• Overgrazing

• Over-cultivation

• Deforestation

• Populstion growth

How does overgrazing cause desertification?

Overgrazing means the vegetation has all gone due to the numbers of animals or the land does not have chance to recover

Overgrazing:

Grazing by livestock and not giving the vegetation enough time to recover

How can over-cultivation lead to desertification?

Over-cultivation leads to all the nutrients being taken up by crops leaving none for future vegetation to grow

How can deforestation lead to desertification?

Deforestation removes shade for the soil and means there are no roots which bind the soil together. This increases soil erosion, whilst decreasing infiltration and interception

How can population growth lead to desrtification?

Population growth puts increased pressure on the land as people raise more animals and grow more crops

Deforestation:

the felling and clearance of trees

Natural cause of deforestation:

• Wildfires are a natural cause of deforestation:

  • The frequency and severity of wildfires have increased this is linked to climate change

Human causes of deforestation:

• settlements- more space is needed for housing

• Logging- trees r felled for timber

• Agriculture- huge areas cleared for plantations

• Mining- clearance of land required

• Road building- space needed for construction

• Hydropower- dams + reservoirs need area

(i)   Define the term deforestation           

(ii)  Outline two causes of deforestation (6)

• Answer:

• (i) 

  • The maximum mark requires a full and accurate definition

  • The felling (1) and removal/clearance of trees (1)

• (ii)

• Any two of the following to gain 1 mark to each for the cause with the 2nd mark for outlining/expanding linked to 1st mark so that cause is clear 

  • Hydropower (1) to make space for dams and reservoirs (1)

  • Mining (1) to make space for mining equipment and buildings (1)

  • Agriculture (1) for grazing or planting crops (1)

  • Settlement (1) to make space to build houses (1)

  • Timber (1) for furniture/building/paper (1)

  • Roads (1) to gain access to transport resources and people (1)

• Factors need to be specific not just human activity or climate

The last ice-age ended approximately…years ago

25,000 years

Natural causes of climate change:

• Milnakovitch cycles

• Volcanic eruptions

• Sunspot activity

• Atmospheric dust

Milankovitch cycles :

• Long term changes to the Earth's orbit and position. This changes how much solar radiation the Earth receives

What are the different elements of the Milankovitch cycles?

• Eccentricicty

• Obliquity

• Precession

What is eccentricity and how does it cause climate change?

• The Earth's orbit changes every100,000 years a more circular orbit leads to cooler periods and an elliptical orbit leads to warmer periods

What is obliquity and how does it cause climate change?

• The Earth's tilt varies every 40,000 years and the greater the tilt the hotter summers are and colder the winters are

What is precession and how does it cause climate change?

• Every 24,000 years the Earth wobbles on its axis and this can affect the seasonal temperatures. The direction the earths axis is pointed at.

How do volcanic eruptions lead to climate change?

Large scale eruptions lead to vast quantities of ash being ejected into the stmosphere. Ash in the atmosphere blocks solar radiation leading to a decrease in temperatures

How does sunspot activity lead to climate change?

ncreased sunspot activity is linked to higher average temperatures

How does atmospheric dust lead to climate change?

• Asteroids and meteors entering the Earth's atmosphere may increase the amount of dust which decreases temperatures 

What is the greenhouse effect?

When short-wave radiation from the sun passes through the atmosphere and greenhouse gases absorb some heat, the rest of the long-wave radiation is given off by earth. This maintains the earth’s average temperature.

Greenhouse gases from Natural sources:

• Water vapour - evaporation from the oceans/seas and plants

• Carbon dioxide - volcanic eruptions, wildfires and respiration

• Methane - emitted from oceans and soils as part of decomposition, termites also emit methane

• Nitrous oxide - soils and oceans

Enhanced greenhouse effect:

The increase of greenhouse gases due to human activity, leading higher temperatures.

Sources of CO2 from Human activity:

• Burning of fossil fuel

• Burning of wood

• Deforestation - leaves use CO2

Sources of Methane from Human activity:

Decay of organic matter

Sources of Nitrous oxide from Human activity:

• artificial fertilisers

• Burning fossil fuels

Social impacts of desertification:

• Malnutrition

• Food shortages

• Migration (lack of food)

Environmental impacts of desertification:

• -ve plant growth

• loss of biodiversity

• Sedimentation

• increased deforestation

Economic impacts of desertification:

• Decreasing income for farmers

• Increased rural poverty

• Dependance on aid

• Decreased investment in communities

Monoculture:

an area where only one crops is grown for profit

Environmental impacts of deforestation:

• loss of biodiversity

• v interception/infiltration = v evapotranspiration= v precipitation

• sedimentation

• enhanced greenhouse effect

Social impacts of deforestation:

• increased quality of life for some ppl

• increased risk of landslides

Economic impacts of deforestation:

• more jobs available

…….. can be used to increase water supply at areas risk

Desalinisation

What is desalination?

Desalination is the process of removing salt and other impurities from seawater produce fresh water suitable for human consumption or industrial use.

How do contour stones and terraces reduce desertification?

• These help to reduce soil erosion by:

  • Preventing the soil from being blown or washed away

  • Increasing infiltration of water and reducing overland flow

  • Ensuring that dead organic matter stays in one place and can decompose adding nutrients to the soil

How does drip irrigation prevent desertification?

Water soaks slowly

Describe how deforestation is being managed in one named area. (4)

• The Marajo project aims to preserve 90,000 hectares of Amazon forest (1) 

• It includes a tree nursery which grows saplings to replace trees which have been felled (1).

• The new trees bind the soil together reducing soil erosion (1). 

• It encourages agroforestry with an açai berry cooperative which reduces deforestation and the need to over cultivate (1). 

• The project also supports agricultural education to introduce sustainable farming methods (1)

Adaptation:

Taking action to get used to the effects of an issue

Mitigation:

Taking action to reduce the scale of damage or prevent the issue

Uk’s response to climate change:

• The UK passed the Climate Change Act (2008) which:

  • Commits to cutting emissions by at least 80% from 1990 levels by 2050 since changed to 100%

Bangladesh response to climate change:

The Bangladesh Climate Change Strategy and Action Plan was adopted in 2009. Bangladesh has pledged to reduce emissions by 22% by 2030