Environmental impacts and the potential for sustainable food supplies

To explain the environmental impacts of the global food system. To consider the potential for sustainable food supplies. To compare two contrasting agricultural systems. Learning objectives

Question! How much of the world’s greenhouse gas emissions is the global food system responsible for? Most emissions: 1.Agricultural production 2.Fertilizer manufacture 3.Refrigeration Also includes indirect emissions from deforestation and land-use changes. Most emissions: 1.Agricultural production 2.Fertilizer manufacture 3.Refrigeration Also includes indirect emissions from deforestation and land-use changes. One third! 20% of the UK’s greenhouse gas emissions are related to food supplies!

Food travels long distances between farmer and consumer. Transportation methods have different impacts: o Large volumes of food can be imported by container ships and pollution levels are low. o Airplanes have high amounts of pollution for the low volumes they carry. Food travels long distances between farmer and consumer. Transportation methods have different impacts: o Large volumes of food can be imported by container ships and pollution levels are low. o Airplanes have high amounts of pollution for the low volumes they carry. Impacts of food transportation Look at Figure 6.24 on page 235. What is the biggest source of food transport pollution in the UK?

The term 'sustainable development' according to the Brundtland Commission is "development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. What is sustainable agriculture? Sustainable agriculture refers to the ability of a farmer to produce food indefinitely without causing irreversible damage to the local ecosystem.

Key issues in promoting sustainable agriculture Biophysical The long term effects of various practices on the soil, habitats, waterways, atmospheric quality and other aspects of the environment. Socio-economic The long term ability of farmers to obtain inputs and manage resources, such as labour.

Unsustainable farming practices In Madagascar only 34% of the primary forest remains. Much of it has been destroyed due to the demand for land to grow coffee for export (cash crop). 1. Deforestation Reduction in interception Soil erosion Flooding Global warming

The root system dies, so there is nothing to bind the soil together, resulting in erosion. The top soil is washed or blown away, leading to the silting up of rivers and localised flooding. There is no canopy to protect the soil from leaching. Lack of leaves, therefore nutrients are not returned to the soil, rendering the soil infertile and dependent on fertilisers. Other impacts involve loss of way of life for indigenous tribes, loss of wildlife, global warming… Impacts of deforestation

Traditionally, crops would have been grown on a smaller scale. Trees would have been planted around plots, providing fruit, nutrients to the soil, and roots to stabilise the ground. To increase output, boundaries have been removed, farming has become mechanised and output relies on applying fertilisers and pesticides. Environmental damage: Soils compaction Loss of habitats Soil erosion / desertification Eutrophication Environmental damage: Soils compaction Loss of habitats Soil erosion / desertification Eutrophication 2. Intensification Unsustainable farming practices

Can you place the following labels in the correct place on your diagram? The process by which a body of water acquires a high concentration of nutrients, especially phosphates and nitrates. These promote excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water of available oxygen, causing the death of other organisms, such as fish. Eutrophication

Can you place the following labels in the correct place on your diagram? Algae die Microbes respire and use up oxygen Aquatic animals suffocate and die Fertilisers wash into a lake or river Algae grow faster Some plants die Plants shaded by algae Dead algae and plants decompose by microbes Dissolved oxygen levels fall Place the labels below on the correct place on your diagrams. Activity: Eutrophication diagram

3. Over Irrigation Salinisation is the process that leads to an excessive increase of water soluble salts in the soil, rendering the land un-cultivateable. This can be caused by human interventions such as inappropriate irrigation practices, e.g. with salt- rich irrigation water and/or insufficient drainage. Unsustainable farming practices

Activity: Unsustainable farming practices There are five main causes of unsustainable agriculture practice and degradation of the countryside: policy failure, rural inequalities, resource imbalance, unsuitable technologies and trade relations. Read and make notes on the information on pages Do the same for the four strategies that help to achieve sustainable agriculture (page 236). Read and make notes on the information on pages Do the same for the four strategies that help to achieve sustainable agriculture (page 236).

A sustainable agricultural system is one that can indefinitely meet the requirements for food and fibre at socially acceptable, economical and environmental costs (Crossen, 1992) Poly-tunnels in Spain The Dogon plateau, Mali Sustainable farming practices

1.Read the case studies of the Dogon Plateau, Mali and Spain’s Plastic Revolution. 2.Complete your comparison table. Summarise the main strategies implemented to increase food supply, then list the advantages (in terms of sustainability) and disadvantages of each system. 3.Draw an agricultural systems diagram (inputs/processes/outputs) for both case studies. 1.Read the case studies of the Dogon Plateau, Mali and Spain’s Plastic Revolution. 2.Complete your comparison table. Summarise the main strategies implemented to increase food supply, then list the advantages (in terms of sustainability) and disadvantages of each system. 3.Draw an agricultural systems diagram (inputs/processes/outputs) for both case studies. Activity: Sustainable food supplies