Don O’Connor NBB Sustainability Workshop September 27, 2018 CARB’s AEZ Model Don O’Connor NBB Sustainability Workshop September 27, 2018

Agenda AEZ Review US Forest Service Data Steps forward

ILUC Emissions ILUC emissions are a two stage calculation What is the land use change? Magnitude and type? GTAP results What is the change in the emissions resulting from the land use change? GTAP land use change and the AEZ emission factor model.

Forest Land In GTAP, generally more pasture land is converted than forest land. But emissions per ha for forests are much larger than for pasture. In general the improvements made to GTAP over the past few years have reduced the proportion of forest land in the converted land and the proportion of land conversions in the developed world.

AEZ Model Forest carbon pools in forest land include Above Ground Biomass Below Ground Biomass Understory Deadwood Litter Soil carbon Foregone sequestration

AEZ US Data USA-10 61 15 19 70 USA-11 49 USA-12 43 44 Mg C ha-1 USA-7 Aboveground carbon (in live biomass) Belowground Carbon Understory Deadwood Litter Topsoil C (to 30 cm) Foregone sequestration over assumed time horizon Mg C ha-1 USA-7 38 10 3 11 26 47 20 USA-8 57 14 89 USA-9 90 22 95 USA-10 61 15 19 70 USA-11 49 USA-12 43 44 USA-13 59 28 72 USA-14 67 16 93 USA-15 105 25 121 USA-16 132 32 148 Typical avg 56 60

US Forest Service The United States is currently in the process of adopting a new approach to forest carbon accounting. The Forest Carbon Accounting Framework (FCAF) will incorporate the most consistently measured annual forest inventories (including all the pools of forest carbon). Data on the individual pools is available at the state level and overall data is available by year since 1990.

USFS Data State data could be aggregated to the AEZ level for the various carbon pools. Trend data could be use to confirm lost carbon sequestration potential from land use change. The online data is not ideal Area by state is 2010 data Total carbon pool data is 2014 data.

USFS Data Min Max Average Tonnes C per ha Above Ground Biomass1 12.4 95.7 50.9 Below ground Biomass 2.4 20.0 10.1 Deadwood 2.3 28.3 8.7 Litter 3.9 18.0 9.8 Total 21 162 79.5 Soil Carbon 17.1 168 60.4 1 Includes understory

Comparison We are comparing the US average forest data to the average of forest land converted in GTAP. These may not be exactly equivalent. Converting the US state data to AEZ data would provide a better comparison.

Comparison AEZ USFS Tonnes C per ha Above Ground Biomass1 59 50.9 Below ground Biomass 14 10.1 Deadwood 11 8.7 Litter 20 9.8 Total 104 79.5 Soil Carbon 60 60.4 1 Includes understory

Observations AEZ model is consistently higher than the USFS data for all categories except soil carbon. The total biomass is 31% higher.

Sequestration US forests are gaining carbon. Through forest area expansion Through increased carbon stocks in forests remaining forests. Contribution of each component varies with the region.

Net Sequestration

Sequestration

Foregone Sequestration An average of 130 million tonnes of carbon have been sequestered since 2010. Forest area is about 270 million ha. Net sequestration rate is 0.48 t C/ha/year. Net sequestration over 30 years is 14.5 t C/ha. This is also lower than the 20 t C/ha in AEZ.

Other Factors USFS also estimated the carbon in harvested wood products as part of the national inventory. This could be compared to the AEZ model as well. Other developed regions of the world will also have forest carbon stock data. Data quality will vary by region.

Next Steps Given that US forest stocks is no longer a large driver of ILUC for most domestic crops is it worthwhile to update the data? If yes, Get forest area data for 2014 to replace the 2010 data that has been used here with the 2014 stock data. Convert state data to AEZ regions. Publish

Next Steps Investigate the availability of similar high quality forest stock data for other GTAP regions. If available, convert to AEZ compatible data.

Questions?