Lecture 9 - Land use, agriculture and NETs

Question 1

What drives land use?

Answer 1

Foo and meat consumption patterns
Crop and livestock yields
Food trade balance
Bioenergy farms and yields
Land multi-use
Land degradation
Water and residues

Question 2

What is the area of land required for food production dependent on?

Answer 2

• Population growth
• Per capita food consumption
• Agricultural yields

Question 3

Why is meat consumption so impactful on emissions?

Answer 3

• Methane emissions from ruminants

- Crop land required to produce food for livestock

Question 4

What are the key land use mitigation strategies?

Answer 4

Supply side:

• Reduce emissions from croplands and livestock
• Conservation of existing stock (e.g. forests)
• Enhanced carbon sequestration in soils (e.g. afforestation)
• Change in albedo from land use
• Reduce agricultural energy consumption

Demand side:

• Reduction in losses in the food supply chain (1/3 food wasted)
• Dietary changes
• Wood and forestry demands - use of wood in long term products (carbon storage)

Question 5

What is the potential of bioenergy?

Answer 5

• Very difficult to determine
• Usual approach - food/fibre first
• Actual value heavily dependent on assumptions - social, political, economic
• Issue of competing uses for bioenergy resources across the energy sector

Question 6

What is a negative emission technology (NET)?

Answer 6

• One that removes CO2 from the atmosphere

- Sub-category of geo-engineering?

Question 7

Give some examples of NETs

Answer 7

• Ocean fertilisation
• Ocean alkalinity addition
• Accelerated chemical weathering of rocks
• Manufacturing carbonate minerals using silicate ricks and CO2 from the air
• Direct CO2 air capture
• Biomass energy with CCS (BECSS) - closest to large scale commercialisation
• Afforestation/reforestation - but how can we be sure that the forests will be there in the long term? Also, some studies say that we have overestimated the amount of CO2 that trees can take up.

Question 8

How likely is it that we’ll need NETs?

Answer 8

• IPCC AR5 database - 101/116 scenarios that achieve a likely change of staying below 2C include BECCS. 60% said BECCS represented more than 20% of the worlds primary energy by 2100

Question 9

Can we deploy enough BECCS to achieve climate targets?

Answer 9

• Challenging - relies on assumptions which are not fully understood, e.g. available land, future yields, storage capacity, technology uptake, capture rate, policy framework, social acceptability

Question 10

What are the main uncertainties around NETs?

Answer 10

• Sustainability of large scale deployment vs other land use and biomass needs (food, biodiversity)
• Response of natural land and ocean carbon sinks to negative emissions
• Costs and financing of untested technologies
• Socio-institutional barriers - public acceptance, deployment policies