Terms in this set (44)
The transformation of once habitable land into desert due to changes in the climate and human misuse of the land
Desertification is usually indicated by...
Declining vegetation cover, soil fertility and potential productivity
Proof that desertification is a global phenomenon (facts/statistics)
Found on every inhabited continent, 38% of world's land, 4 billion hectares, 110 countries, more than 850 million people directly affected, 135 million people at rick of being displaced, US$42 billion lost annually in agricultural production
Proof that desertification requires more than a local or national response (facts/statistics)
UNCCD has 195 signatures, GEF set aside US$15 million, international monitoring, research and assistance, CARE International, World Bank
Distribution of desertification: Pattern
Uneven, clusters occur between 20 to 40 degrees north and south of the equator, concentrated in central and western regions of large landmasses, associated with hot, dry descending air and cold air above cold ocean currents
Distribution of desertification: Quantification
80% of all desertification follows the pattern, spatially associated with existing deserts (Sahara, Gobi, Kalahari, Simpson)
Distribution of desertification: Exception
North-east region of Brazil (on the east coast, approximately 10 degrees south of the equator), central Russia (more than 60 degrees north of the equator)
When the cattle numbers in a region is at a level that does not allow the vegetation to recover, or when animals graze at inappropriate times of the flora/fauna cycle
Impacts of overgrazing
Soil is left bare, trampled, compact and devoid of vegetation, soil becomes susceptible to erosion and reduced water intake
Causes of overgrazing
Social (more animals = higher status, population increase = higher food demand = grazing more animals).
Economic (continues because it returns an economic income), better veterinary care, vaccinations and animal health programs cause fewer animals to die
In the Sahel: 1 animal to 12 hectares (1970s), 12 animals to 1 hectare (now).
Niger: 14% of national GDP is from animal cultivation.
Over-cultivation definition and impacts
The intensification of farming to such an extent that the soil fertility is exhausted
Causes of over-cultivation
Places growing one crop per year now grow mutiple per year, some governments have encouraged the growth of food for export rather than local consumption
Study in Calabar South, Nigeria: 60% yield reduction on over-cultivated land
Impacts of fuel-wood clearing
Loss of trees reduces protective cover of vegetation on the soil, reducing soil moisture and increasing soil-erosion issues
Causes of fuel-wood clearing
Firewood is the main source of fuel for cooking and cleaning in many countries
Fuel-wood clearing stats
90% of trees cut down in Africa and 40% in Asian and Pacific countries are used for fuel, Burkina Faso and Sudan: no trees within 80km of capital cities
Impacts of population changes
Exacerbates land degradation, puts pressure on fertile land in other locations
Causes of population changes
Migration, drought, rural-urban migration
Population changes stats
Sahel: natural increase rates of 2.5% - 3.9% in 2014, fertility rates of 4.1 - 7.6 in 2014, 85 million people relying on marginal land to increase to 100 million by 2020.
Mauritania: 41% city population in 1990, 64% in 2005.
Mali: 14 million now, 41 million in 2050, fertility rate of 6.54.
Eritrea, Somalia, South Sudan: 1.4 million fleeing.
Impacts of water extraction and unsustainable farming practices
Water table rising, soils saturated, salts mobilise
Water extraction and unsustainable farming practices stats
Aral Sea: Amu Darya and Syr Darya were diverted for the growing of cash crops, particularly cotton, 40% of land along rivers are unsuitable for crops due to salinity.
Lake Chad: freshwater lake, once 25,000 sq km, reduced to 1,350 sq km.
Salinisation: affects 1/2 the world's irrigated land, affects 1/3 of all arable land.
Australia: 5.7 million ha of land affected by dryland salinity in 2000, increase to 17 million in 2050.
Impacts of changes in traditional farming methods
Puts pressure on the already stretched local resources
Causes of changes in traditional farming methods
Increasing populations, government policies
Changes in traditional farming methods stats
73% of total population in Mauritania were nomadic, less than 4% in 2000
Impacts of climate change
Increase the scale of droughts in semi-arid and sub-humid regions, dry climate = higher risk of desertification
Causes of climate change
Greenhouse gases (industry), electricity generation and use, cars
Climate change stats
North America: 1939, strong winds causes severe wind erosion, 75% of topsoil blown away.
Southern Europe: average precipitation decline of 22% over the last few decades.
Mauritania: the isohyet indicating annual rainfall of 150mm has moved southward by 100km.
Sudan: 1961 - 1990, 65% variation of precipitation in North Kordofan, 15% variation of precipitation in South Kordofan per annum.
Impacts of natural disasters
Fires: reduce vegetation cover, can change the type (no regeneration), expose topsoil, susceptible to wind and water erosion, decline in soil fertility
Drought: expose the land to wind erosion, decline in soil fertility
Natural disasters stats
Sahel: 1970s worst drought in 150 years, 1980s, 2000s.
Mali and Burkina Faso: 17% of rural inhabitants lost land due to drought
Local Case Study - Niger: negative impact on environment
Majjia Valley was once a fertile and heavily vegetated area.
Valley floor and sides were cleared to permit the cultivation of crops.
Remaining trees were cut down and used as fuel.
Dry Harmattan winds blew at 60km/hr, eroded topsoil at 20 tonnes/hectare each year.
Hillsides left bare and denuded.
Local Case Study - Niger: response name and aim
Name: The Majjia Project (1974).
Aim: to create windbreaks to stop strong winds continually stripping topsoil out of the Majjia Valley.
Local Case Study - Niger: response description (strategies)
Two local foresters obtained financial and technical support from CARE International.
Nigerien Forest Service provided need seedlings annually.
From 1974, trees were planted over a 300km belt.
Seedling survival rate was impressive, partly due to the shallow water table.
Guards were hired to protect seedlings from livestock in the first few years.
Local Case Study - Niger: effectiveness of response
Neem and native Acacia trees developed into an effective windbreak.
Soil moisture increased, Valley was protected by the wind.
Crop yields increased by 20% even though arable land decreased by 15%.
After 11 years (1985), villagers were able to sustainably harvest the trees as a fuel wood source.
Trees were pollarded in June and has shoots 2m long and 5cm wide in November 1985
Local Case Study - Niger: future/success in other areas
Project was replicated by IFAD.
Showed that with careful management, land can be restored.
Was a lighthouse project for all communities facing desertification.
15 million trees planted in Niger since 1974.
National Case Study - The Aral Sea: negative impact on environment
Aral Sea was once the fourth largest inland lake, 65,000 sq km (size of Tasmania).
The former USSR's push to grow cotton and rice in the 1950s in the Kara Kum Desert meant that its two feeder rivers (Amu Darya and Syr Darya) were diverted).
Water receded in the Aral Sea and the sea floor became exposed.
Salts increased by 300% from 1980 - 1990.
15 fish species and over 160 animal species died out.
Over 16,000 sq km of sea floor became desert.
Climate became drier and more severe.
National Case Study - The Aral Sea: negative impact on people
Tuberculosis reached epidemic proportions.
Infant mortality quadrupled.
Acute respiratory illness soared.
Potable water became scarce.
Aral Sea fishing industry destroyed - once employed 40,000 people).
100,000 people displaced.
Impacted on the health of 5 million people.
Aralsk: 70% - 80% of women suffer from anaemia.
National Case Study - The Aral Sea: response name and aim
Name: The Kokaral Dam Project (2005).
Aim: to stop water from the Syr Darya spreading out too quickly and evaporating.
National Case Study - The Aral Sea: response description (strategies)
Build a 12km levee across the neck of the North Aral Sea, just south of where the Syr Darya enters.
Completed in August 2005.
Funded by the Kazakh Government and the World Bank.
Cost US$85 million.
Rebuilding 60km of irrigation channel along the Syr Darya using MDB technology.
Proceeded two attempts (1992 and 1996) to build a dam using sand, funded and built by locals - both successful but were washed away by water.
National Case Study - The Aral Sea: effectiveness of response
Over 450km of dry seabed covered up to depths of 40m (42m considered level of viability).
Flow rates into the sea doubled (irrigation upgrade).
11 species of fish returned.
2008: 1500 tonnes of fish caught sustainable by rejuvenated fishing industry.
Shoreline: 90km away from Aralsk in 2006, 20km away in 2010.
Rainfall increased 100mm/year.
Temperatures decreased by 2.5 degrees.
National Case Study - The Aral Sea: future
Success for the North Aral Sea, future of South Aral Sea still bleak.
Expected that by 2020, the South Aral Sea will disappear.
Tajikistan (upstream) threatening to dam Syr Darya for hydroelectricity.
Global Case Study - Great Green Wall: response name and aim
Name: Great Green Wall Initiative (GGWI).
Aim: to address the detrimental social, economic and environmental effects of desertification and land degradation in the Sahel and Sahara
Global Case Study - Great Green Wall: response description (strategies)
March 2011 in Bonn, Germany: GEF accept proposal of 11 countries.
GGW to stretch from Djibouti in the horn of Africa in the east to Dakar, Senegal in the west, on the southern edge of the Sahara Desert.
15km wide and 7775km long.
US$3 billion pledged by GEF and others.
37 species of drought-tolerant plant species have been selected.
Global Case Study - Great Green Wall: effectiveness/future
Potential to be very effective - Nigeria planted 132km of trees of targeted 181km (73%) from July - September 2014.
Challenges still remain - US$3 billion may not be enough, additional funding not guaranteed.
Sahelian growth rate is 2.5% - increased demand of fuel wood and food security.
Co-operation over 11 countries may create complications.