Lecture 3: Water and food

Question 1

So that we now live in:

“The Anthropocene” (the age of humans)

Answer 1

It seems appropriate to assign the
term ‘Anthropocene’ to the present, in many
ways human-dominated, geological epoch,
supplementing the Holocene — the warm 
period of the past 10–12 millennia.”

Question 2

Our landscapes are dominated by Anthromes, not Biomes

Answer 2

Classic paradigm: Biosphere shaped primarily by biophysical systems.

Anthromes paradigm: Most of the biosphere reshaped by human systems

Question 3

Livestock has also grown:

Answer 3

For milk, meat, (by-products textiles, leather, fertiliser)
increasing globally and especially in developing world
Decreasing in e.g. USA
Huge international market flows
35% of crop growth goes to animal feed (

Question 4

Livestock densities

Answer 4

Greater than human population density in some countries
Densities >50/km2 for cattle and goats over large areas
Have replaced large wild mammals over vast areas

Question 5

Fisheries have also grown enormously

Answer 5

Especially marine capture fisheries

We are now looking deeper and deeper

Question 6

Water for food

Answer 6

Water for Food – on average 1 litre of ET per calorie
Most of a person’s water consumption is in what they eat
2.5b more mouths means finding another 2500 - 5000 cubic km of water!

Question 7

Climatically vulnerable zones

Answer 7

Stemming from continued poverty and increasing food prices
Situation may worsen as food prices experience shocks from:
market speculation
bioenergy expansion
climatic disturbance

Question 8

Food production is industrialised and energy dependent:

Answer 8

Dependent on cheap energy, responds to energy scarcity

Food prices declining until recently (perhaps on way back down now)

Question 9

Recent growth in crop production is largely due to gains in yield

Answer 9

Crop production increased by 28-47% 1985-2005 with only a 3% increase in cropland area,

Meaning 20-25% increase in yield but also multiple cropping, fewer crop failures and less fallow.

Yields increased 56% previously (i.e.1965-1985) so they are now increasing less rapidly.
Increases due to: fertilisers, irrigation, new varieties, pesticides

Land expansion and intensification have contributed less (as we have moved i

Question 10

Agricultural gains

Answer 10

These inputs have environmental impacts

Growth in production has been impressive but environmentally unsustainable

Question 11

These agricultural impacts (and agriculture itself) are complex

Answer 11

Impacts result from expansion and intensification

Expansion impacts upon habitats, biodiversity, carbon storage and soil

Lost 70% of grasslands, 50% of Savanna, 45% temperate forest, 25% tropical forest to Ag.

80% of new croplands in the world are replacing tropical forests (12% anthro. CO2 emissions)

Has done little to increase food security (most gains from intensification)

Question 12

Intensification impacts upon most environmental systems

Answer 12

Past 50 years irrigated cropland area doubled (80-90% of global consumptive water use is irrigation)

Global fertiliser use increased by 500%

Increased energy use (Ag. responsible for 35% of GHG emissions)

Widespread pollution of water and disruption of nutrient cycles

Impacts on aquatic and marine fisheries

Question 13

There are significant impacts on the biosphere as intensification increases

Answer 13

Agriculture is the dominant force in GEC
Loss of biodiversity
Loss of ecosystem services

Question 14

Also significant impacts on land degradation

Answer 14

Observed declines in productivity

Associated soil erosion, nutrient exhaustion…

Production becomes unsustainable

Question 15

Sustainability: much of agricultural growth is based on finite resources

Answer 15

e.g. fossil groundwater, fossil fuels

Increasing groundwater usage is a “water time bomb” for ag. sustainability