Deserts - desertification

what's the impact of desertification on the human population

- A reduction in the fertility of land causes a decline in agricultural productivity - if it decreases to the point where farmers can earn a substantial living they may have to migrate, This increases pressure on the land they move to allowing the cycle of desertification to repeat. - If people are unable to move then desertification can lead to famine. - Desertification can also affect human health in other ways for example dust from soil erosion can cause respiratory diseases.

give some facts about desertification:

- Africa and Asia are the worst affected areas. - A third of land worldwide is at risk from desertification. - 250 million people across the globe are already affected by desertification - 46% of Africa is at risk of desertification

Whats the social consequence of desertification:

- Desertification is a key factor affecting developments in Kenya, Ethiopia, Djibouti and Somalia. - Desertification affects food security, where desertification degrades the natural resource base for animal and vegetal production.

give an example ti show changing extent of deserts:

- The Sahara wasn't a desert from about 11000 to 5000 years ago. This period was known as the 'green Sahara. - Around 10-5000 years ago, conditions changed dramatically when monsoon rains transformed the former desert land into lush grasslands. - Since then various climatic fluctuations have transformed it into the desert area that we know it as today. - Whilst changes to hot deserts thousands of years ago were down to natural climatic variations, but in more recent times, humans have also started to influence the extend and distribution of deserts.

Whats the political consequence of desertification:

-The social and political consequences of desertification can also reach non-dryland areas. For example human migration (caused by desertification ) from drylands to cities and other countries can harm social and political and economic stability.

Define the process of desertification:

1. Many people in LICs are poor so have large families. This results in rapid population growth 2. This population growth means people plants more crops and so larger amounts of deforestation occur The population also needs more wood for building fires, homes and animals. 3. The people move to another area of land and begin to clear some space leading to more vegetation being destroyed 4. The soil loses its structure and is easily eroded and blown away in the wind 5. The land is not allowed to rest and recover so loses its fertility and becomes exhausted 6. Soil becomes so infertile that crops will not grow and there is nothing for animals to eat 7. The land becomes infertile, barren so people move to elsewhere and the cycle repeats.

what's the link between desertification, global climate change, and biodiversity loss:

Desertification diminishes biological diversity, a diversity which contributes to many of the services provided to humans by dryland ecosystems. Vegetation and its diversity are key for soil conservation and for the regulation of surface water and local climate. Desertification also contributes to global climate change by releasing into the atmosphere carbon stored in dryland vegetation and soils. The effect of global climate change on desertification is complex, on the one hand, higher temperatures resulting from increased CO2 levels can have a negative impact through increased loss of water from soil and reduced rainfall in drylands.

who is affected by desertification:

Desertification threatens the livelihood of more that one billion people world wide. It mainly affects people in agriculture and whose livelihood depends on the land under threat from desertification, these are also mainly people living in developing countries. Desertification forces nomads and pastoralists to look for different grazing routes and even change their annual trekking routes.

What are the physical causes of desertification:

Erosion Flooding Salinization Drought Climate change: Climate change causes desertification by reducing rainfall and increasing the temperature in some areas. temperature increases the rate of evapotranspiration also increases. This dries out soils and lowers surface water levels, leading to soil erosion and death of vegetation. reduce rainfall in sub-tropical regions Less rainfall means surface water and groundwater will be reduced. Therefore the volume of water available for vegetation growth is reduced leading to the death of vegetation The roots of plants and trees bind the soil together. Fewer plants and trees mean fewer roots, leading to soil erosion.

Whats the economical consequence of desertification:

In some countries desertification impact on the economy can be equivalent to 8% of annual GDP- enough to negate growth and stall development.

What are the human causes of desertification:

Overgrazing: reduces vegetation so loads so soil erosion due to the lack of plant roots. Trampling by large numbers of animals also compresses and breaks down the structure of the soil, which also makes erosion more likely. Over-cultivation: reduces soil productivity as the over-exploitation of the soil leaves it without enough nutrients to support plants and so soil is easily eroded. Agricultural activities: this leads to deforestation which removes trees and roots destabilizing the soil and making it vulnerable. Population growth: increases pressures on the land as more and more food is needed to supply the growing demand. This in turn leads to further over grazing, overcultivation, deforestation and irrigation. Irrigation depletes surface water and may involve the unsustainable pumping of aquifers. As water levels are lowered, water availability for plants decreases, leading to soil erosion. Irrigation can also raise groundwater levels if too much water is used for irrigation. This can increase the salinity of the soil, which may cause plants to die.

Predicted climate change and its impacts; alternative possible futures for local populations.

Poverty and unsustainable land use practices will continue to be the main factors driving desertification in the near future, and climate change will also play a role. → Climate change: its predicted that climate change will increase desertification, as climate change is due to make semi-arid areas hotter and drier. The 3 main possible futures can be simplified to be: Desertification may increase: if action isn't taken to reduce desertification, or if strategies are not funded or managed properly, then the rate of desertification could increase, leading to large areas of degraded land. The reduction in agricultural yields would increase famine and malnutrition and this could hinder development in affected countries. There may also be conflict between countries suffering from desertification, as food and water become more scarce. Humans may stop or reverse desertification: further desertification could be prevented and some desertification reversed if major action is taken. Locally people could plant vegetation to bind soil and act as wind breakers. Farmers can carry out crop rotation to allow the soil to recover and improve irrigation systems. Humans may reduce the impacts of desertification: Local populations may change their lifestyles in order to adapt to desertification and reduce its impacts. For example, local farmers could change their farming methods to reduce the impacts of desertification on their livelihoods. Improvements in agricultural technology could allow farmers to increase the amount of food they produce per hectare, helping to prevent food supplies from decreasing as more land become unsuitable for farming.

what's the impact of desertification on the land

The ground surface becomes more prone to erosion, because: - Removal of vegetation cover increases wind speed - Moisture evaporates from the soil more quickly when its not sheltered by plants so it dries out - Plant roots help to bind the sediment together Increased erosion can expose bedrock. Higher wind speed and more mobile sediment can also cause more sand to be blown into an area.

describe the changing extent and distribution of hot deserts over the last 10,000 years:

changing climates change their extent and tier distribution. After the last glacial period ended about 11500 years ago, the climate in many parts of the world became wetter, which reduces the amount of land covered by deserts. About 9000 years ago in the early holocene, the only hot deserts in the world were narrow strips on the west coast of Africa and south america In the present day aridity has returned to Africa and Asia and the extent of hot deserts has increased significantly.

why is it difficult to measure desertification:

difficult to accurately measure desertification as uncertainties remain about the way various biological, physical, social, and economic factors interact, which limits our ability to assess the actual effect and extent of desertification. There is also no one concrete definition of what classifies as desertification making it difficult to measure

what's the impact of desertification on the ecosystem

ncreased erosion of soil and encroachment of dunes has major impacts on ecosystems. - As land becomes less fertile, less plant life can grow- this reduces the amount of organic matter that is put into the soil further reducing vegetation growth. Less vegetation means less animal life can be supported and biodiversity increases. - Desertification also changes the distribution of species. Plant and animal populations that were present in regions now transformed by desertification may have to migrate to migrate

Define desertification

persistent desertification of dryland ecosystems by variation in climate and human activities. It results in a reduction or loss of the biological or economic productivity of drylands.

Whats the environmental consequences of desertification;

threat to all wildlife and ecosystems in areas where desertification is occurring. -Desertification also has environmental impacts that go way beyond the areas directly affected. For example, loss of vegetation can increase the formation of dust clouds that can cause health problems in more densely populated areas.