Fragile environments & climate change igcse geography

How does HEP cause deforestation?

-rivers are damned and huge areas of forest are flooded as a result

How does road building cause deforestation?

-roads built through rainforest to enable minerals , timber , cattle +crops to be moved easily -roads bring in new settlers who clear areas for farming

What are environmental impacts of desertification?

-seasonal rivers and water holes dry up, so organisms which live in the, or rely on them for water may die -Vegetation dies causing animals depending on it for food/shelter to perish or migrate -Increased soil erosion. Eroded material is washed into rivers or water holes resulting in contamination

Define the term desertification.

The term used to describe how once productive land gradually changes into a desert like landscape

process of desertification please look at diagram

Look at diagram

What is the positive feedback loop for human causes of desertification?

Population increase leads to (more fuel wood needed which leads to deforestation which means the soil is left bare) and (more food is needed which leads to over cultivation of land so the soil becomes worn out) Leading to soil erosion and then desertification Agriculture means there is more strain on the soil leading to soil erosion and then desertification As the soil becomes worn out and people can't afford fertilisers this leads to poverty

What are some attempted solutions to deal with desertification in the Sahel?

-encouraging farmers to grow drought-resistant crops -improving knowledge and understanding of droughts across the region by launching the Africa Climate Exchange -Use of drip irrigation systems to reduce water usage -lines of rocks are placed across the land to slow flowing rainwater and encourage the deposition of sediments (rich in nutrients). This is a cost-effective option

How does mining cause deforestation?

-large areas of rainforest cleared for the open-cast mining of minerals such as iron, gold and copper

What are some causes of deforestation?

-commercial logging/timber extraction (globally 26%) -road building -land for farmers -agriculture (globally 32%) -mining -HEP(hydroelectric power)

What are the causes of desertification

-drought -population pressure -fuel supply -overgrazing -migration

How does land for farmers cause deforestation?

-allows farmers to grow their own food -wood cut down provides them with fuel -stops overcrowding in other parts of the country

How is loss of biodiversity a consequence of deforestation?

-80% of documented species found in tropical rainforests (some most vulnerable to deforestation) -when homes of species lost, they are often unable to survive in the small fragments of forested land left behind. May go extinct even after small scale deforestation -Biodiversity is an important natural resource, providing us with , many goods and services e.g.food, timber, drugs, medicinal. W/out it humans could die

What are the characteristics of desertification?

-Absence of surface water -Dried up watercourses and ponds -Lowering of the water table -Vegetation becomes degraded or completely lost -Increased soil erosion as bare soil is exposed to wind -Increase in salt content of the soil -Soil becomes less usable -Increasing presence of dry loose sand

What are 2 countries that have fragile environments?

-Australia is unsustainable and fragile because it has a lot of deserts , desertification is spreading . The coral reefs are dying due to sea level rise which is a result of climate change/global warming -Madagascar is sustainable but it has a fragile environment as there is a lot of deforestation , habitat destruction and Agricultural fires

What are some examples of greenhouse gases and how are they produced?

-CO2 (by burning fossil fuels , deforestation and burning of wood) -CFCs(chlorofluorocarbons from fridges, packing materials and air conditioning) -Nitrous Oxides (fossil fuels and fertilisers) -Methane(crops especially rice, dead organic matter e.g. landfill and animal manure) The more gases released the greater the greenhouse effect is , trapping more & more heat in the lower atmosphere as it is too thick to allow heat to escape.

Explain the process of desertification

-Desertification starts with an area of land that may be rich with trees and plants but usually semi-arid areas are at a higher risk -Some natural change or human activity may lead to vegetation being degraded or removed -The lack of vegetation leads to reduced transpiration and bare soil being exposed leading to soil erosion by wind and water -Over time, the land becomes drier and t(e soil becomes less fertile leading to a more desert like landscape

Describe the greenhouse effect?

-Greenhouse gases allow sufficient solar radiation through to warm the earths surface -greenhouse gases absorb outgoing radiation, trapping heat in the atmosphere -radiation is re-emitted from the atmosphere back to the earth -some radiation is reflected back into space

What are 3 possible natural causes of climate change?

-Milankovitch cycles - variations in the earths orbit around the sun -Volcanic activity - ash and aerosols ejected into Earths atmosphere by volcanic eruptions can affect Earths temperatures -Cosmic material - similar impact as volcanic activity e.g. meteorites/ space stuff / cosmic material

What are some areas at risk of desertification and why?

-South-south America along the coast due to it being very hot -Most of North Africa due to its intense heat -South Asia and Australia (some parts already desert) -East coast of North America

What are the social impacts of desertification?

-Subsistence farmers crops fail , livestock dies and this can lead to famine and hunger. -Commercial farms growing cash crops such as cotton lose income, which may cause unemployment -with less food being grown and an increase in demand, food prices increase -increased soil erosion makes the land less fertile creating a long term issue for the farming community -clean water is not available for people to drink , increasing the use of contaminated water + diseases such as cholera -people (usually women +children) travel further to find water, which means children miss school and the carrying of heavy loads can lead to back problems

What are some impacts of deforestation?

-flooding (eroded soil is deposited in the rivers ;this increases the flood risk) -loss of forests and burning (this increases the CO2 in the atmosphere and reduces O2 levels; this may add to global warming) -leaching (removing the trees leaves the soil bare; rainfall easily washes away the nutrients) -native tribes (they are forced to live in smaller areas causing them to clear patches of land before the land has fully recovered) -loss of plants and animals / biodiversity (clearing the forests destroys the habitat for many plants & animals) -economic development ( deforestation provides jobs and increases the economy when wood is sold)

How does deforestation contribute to climate change?

-forests absorb CO2 (helps lower greenhouse gas levels) -deforestation contributes to build up of greenhouse gases as less greenhouse gases are absorbed -trees release CO2 when cut/burned/removed -these greenhouse gas emissions contribute to global warming creating rising temps, changes weather patterns and increases frequency of extreme weather events

Give reasons for the high biodiversity of the Amazon rainforest

-has lots of species of animals , insects + fauna -it has a specialised climate -nutrient rich soil + warm + lots of water -high levels of solar radiation -large area -complex food webs Deep soil,wet -insects +microorganisms thrive

How does deforestation affect economic development?

-in LICs, deforestation can stimulate economic development through exploiting and selling resources -Brazil, Indonesia, Thailand and the Philippines have all done this -However, the benefits are only short term unless something is done to replace forests -Deforestation can have devastating consequences on local communities e.g. In Brazil poor people are lured from their villages to plantations where they are forced to work under inhumane conditions

How does commercial logging cause deforestation?

-valuable trees chopped down as they fall, they damage other trees -clear felling where other trees are also chopped down and chipped for pulp which is more damageable

How does deforestation lead to increased soil erosion?

-without trees to anchor fertile soil, erosion can occur and sweep soil into rivers. Agricultural plants that often replace trees can't hold onto soil -many of these plants such as coffee, cotton, palm oil, soybean and wheat can worsen soil erosion -scientists have estimated 1/3 of worlds arable land has been lost through soil erosion and other types of degradation since 1960 -As fertile soil washes away, agricultural producers move on, clearing more forest and continuing the cycle of soil loss

How many countries in the world are under threat of desertification?

110

How much land is lost every year to dertification

12 million hectares

Where is the Sahel?

A narrow belt of land in central Africa that borders the southern edge of the Sahara desert

How much land is affected by soil degradation and desertification?

A third of land

How does agriculture cause deforestation?

Areas of tropical rainforest cleared for plantations growing a single crop such as rubber or coffee -plants + grassland grown, which huge nerds of cattle graze on for a few years before another area is cleared for seeding with grass.

What is the positive feedback loop for the natural causes of deforestation?

Climate change Less rainfall Bare soil Increased water flow overland (water flow washes soil away/soil erosion by water)(water drained from soil so soil is dry and blown away more easily and a dust bowl is created / soil erosion by wind) (water table lowered) Few plants grow and little farming possible Desertification

Where does desertification usually take place?

In semi-arid land on the edges of existing hot deserts

What are 5 human causes of climate change?

Industry Transport Energy Farming practises Deforestation (farming , industry, urbanisation)

What type of soil is more prone to erosion?

The deeper the soil, the greater the ability of the soil to absorb water through infiltration. However hard baked soils are more prone to being eroded by increased surface run off. Exposed souls and dried soil can also be prone to wind erosion

What is the distribution of the worlds fragile environments?

The global distribution of fragile environments is most influenced by the impact of three processes - desertification, deforestation and climate change. The three are linked because the first two are both the causes and consequences of climate change. Together, they are making environments more fragile.