environmental impacts and the potential for sustainable food supplies
TRANSCRIPT
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 manufacture3. 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.
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.
Socioeconomic
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
FloodingGlobal
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 compactionLoss of habitats
Soil erosion / desertificationEutrophication
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 oxygenAquatic
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
235-6.
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
Read the case studies of the Dogon Plateau, Mali and Spain’s Plastic Revolution.
Now complete the table you have been given. Summarise the main strategies implemented to
increase food supply, then list the advantages (in terms of sustainability) and disadvantages of each
system.
Activity: Sustainable food supplies