1. Policy options to achieve the 80% cut Land Management, Sequestration and Sinks
Robin Matthews
Climate Change Theme Leader
Macaulay Institute
Aberdeen AB15 8QH
Presentation at Scottish Parliament, November 19, 2008

2. Structure of the talk Background
Contribution to overall Scottish GHG emissions made by the land use sector
Trends in GHG emissions from the land use sector
Scope for the use of land for sequestration and sinks

3. Emissions from the land use sector
N2O: N-fertiliser, wet acid soils, animals
CH4: livestock, natural peat bogs
CO2: cultivation, fuel consumption
However, Scotland’s soils contain:
Shallow organic soils: ~1400 Mt C
Peat soils: Mt C
Forests and soils have considerable capacity to store carbon

4. Carbon sequestration

5. Effect of land use change on soil C
Geescroft Wilderness: converted from arable to woodland in 1880s
New Zealand
-1.15 t C ha-1 y-1 in first 3 years
average 0.33 t C ha-1 y-1

6. Scale of the contribution
62% of UK’s removals is by Scottish forests (2003)
Scotland’s total emissions: 59 Mt CO2e yr-1
Land use emissions: 11.8 Mt CO2e yr-1
From ‘Changing Our Ways: Scotland’s Climate Change Programme’, SEERAD, 2006.

7. Trends in main GHG source/sinks
Forestry
Livestock
Land use change
N fertiliser application

8. LULUCF source/sink trends
Scotland
decline in cattle and sheep numbers
60% reduction
increase in sink size by 78%
From AEA (2008), Greenhouse Gas Inventories for England, Scotland, Wales & Northern Ireland:

9. Agricultural management
alternative ‘carbon-neutral’ energy crops
increased C sequestration through different ground covers and land management
reducing CH4 emissions from livestock
more efficient use of organic and inorganic fertilisers
Initial calculations suggest abatement potential of 1.57 MtCO2e

10. Land use change: arable to grassland
Scotland: 600,250 ha

11. Land use change: arable to grassland
Abatement potential
Ignoring land suitability for the moment
600,250 ha of cropland in Scotland
Assume all is converted into grassland
Sequestration rate: ~1.5 t CO2 ha-1 y-1
Abatement potentials:
setaside: 0.97 MtCO2e y-1
beef: 0.11 MtCO2e y-1
sheep: 0.40 MtCO2e y-1
dairy: MtCO2e y-1

12. Land use change: forestry
Options
afforestation of abandoned agricultural lands
forest management to increase carbon density at the stand/landscape level
maintaining forest cover
minimising soil C loss
increasing rotation lengths
increasing growth
managing drainage
increasing off-site carbon stocks in wood products
enhancing product and fuel substitution

13. Land use change: forestry
Forestry Strategy: Increase of forestry from 17-25%
Current forest area: 1,347,001 ha
2050 target: 1,969,300 ha (+622,299 ha)
Assume sequestration rate is 11 t CO2 ha-1 yr-1
Abatement potential: 6.8 Mt CO2e yr-1 (12.5%)
‘Changing Our Ways’ (2006): The forestry sector should deliver annual carbon savings of
2.2 Mt CO2e by 2010 (4.0%)
2.9 Mt CO2e by 2015 (5.4%)
3.7 Mt CO2e by 2020 (6.7%)

14. Forest planting rates

15. Tradeoffs for landuse
As climates warm, more marginal areas will become suitable for agriculture
What will be the implications for:
food production
bioenergy
timber
water quality, quantity
soils
carbon storage
biodiversity

16. Land use change: peat restoration
total peat area: 1,096,000 ha
degraded basin peat: ~24,000 ha
eroded blanket peat: ~9,000 ha
functioning peat-bog sequesters ~730 kg CO2 ha-1 y-1
degraded bog could lose ~730 kg CO2 ha-1 y-1
one-off cost of £ per ha
abatement potential: 1460 × 33,000 × = Mt CO2e y-1
0.09% of Scotland’s emissions of 55 Mt CO2 yr-1

17. Summary Abatement potential Fraction of AFOLU Fraction of total
(MtCO2e yr-1)
(%)
Agriculture
1.57
13.3
2.7
Cropland to grassland
0.97
8.2
1.6
Forestry
6.80
57.6
11.5
Peatland
0.05
0.4
0.1
TOTAL
9.39
79.5
15.9
Proviso: Very ‘ballpark’ figures – indicative only!
Many assumptions that need to be tested
More detailed UK study to be published by Office of Climate Change in December

18. Marginal abatement cost curves
Cheap option, big emission savings
Expensive options, small emission savings
Financial savings
Options ranked in decreasing order of cost-effectiveness
Width of each bar (x-axis): abatement potential (AP)
Height of each bar (y-axis): cost-effectiveness (CE)
Comparing the abatement scenario with a baseline
Now I’d like to move on to methodology.
To find out the most effective way of reducing greenhouse gas emissions from agriculture, the marginal abatement cost curve analysis was used.
This illustrative MAC curve shows various options to reduce GHG emissions, ranked in decreasing order of cost-effectiveness along the x-axis.
On the MAC curve, the width of each bar indicates the volume of the emission savings, in other words the abatement potential, while the height of each bar shows the cost-effectiveness of the measure, which is calculated by dividing the total cost of the measure by the abatement potential. Measures below the x-axis indicate savings, while measures above the x-axis illustrate costs
For example, this wide and flat bar indicates an option which is cheap, and at the same time generates huge emission savings. On the other hand, these tall and narrow bars on the right represent expensive options with low abatement potentials.