1. 1 A Global-Scale Biofuels Program and its Environmental Consequences J. Melillo 1, A. Gurgel 2, D. Kicklighter 1, J. Reilly 2, T. Cronin 1, S. Paltsev 2, B. Felzer 1, A. Sokolov 2 and X. Wang 2 1 The Ecosystems Center, MBL, Woods Hole, MA 2 Joint Program on Global Change, MIT, Cambridge MA

2. 2 A Modeling Study Using an Integrated Global Systems Model (IGSM) Developed as part of the MIT Joint Program on Global Change Coupled models within the IGSM –Economic model - a general equilibrium economic model, EPPA (the Emissions Prediction and Policy Analysis model) –Atmospheric chemistry model –Reduced form GCM (coupled AOL model) –Terrestrial biogeochemistry model

3. 3 MIT Integrated Global System Model (IGSM) Prinn et al., 1999, Climatic Change, 41(3/4), 469-546.

4. 4 http://web.mit.edu/globalchange/www/MITJPSPGC Rpt 146.pdf Gurgel, A., Reilly, J. & Paltsev, S. J. Agric. Food Industrial Org. 5(2), 1- 34 (2007).

5. 5 Terrestrial Ecosystem Model (TEM) Melillo et al. 1993, Nature 363: 234-240; Felzer et al. 2004 Tellus, 56B, 230-248

6. 6 Crop yield

7. 7 Examples of Simulations Global-scale simulations – in the context of an interactive global economy Cellulosic biofuels - in the context of other land- use needs (e.g., croplands, pastures, managed forests) Climate change policy target – e.g., stabilize [CO 2 ] at 550ppmv, emissions limits prescribed by economic region (total of 16), cap and trade mechanism in place Primary drivers –Economics (land price, labor costs, etc.) –Policies (e.g., conservation of forested lands)

8. 8 2 Land-use Scenarios Deforestation – all land-cover types can be converted to production to biofuels feedstocks Intensification – protection of forests receives a high priority

9. 9 Absolute land areas in different land uses (million km 2 ) ContemporaryDeforest. Intensif. 20002050 Total Land Area of the Earth 133----------------------------------- Total Area Co- opted for Human Use 42 59 50 Biofuels Area 0 15 14 Crop Area16 20 18 Pasture Area26 24 18

10. 10 a. Deforestation b. Intensification 0 10 20 40 60 80 100 Percent % of grid cell (0.5x0.5 o ) in biofuels

11. 11 Preliminary Simulation Results Deforestation ScenarioIntensification Scenario Land CoverΔCarbon (Pg C) Co-opted NPP (Pg C yr -1 ) ΔCarbon (Pg C) Co-opted NPP (Pg C yr -1 ) Time Period2000-20502040-20492000-20502040-2049 Biofuel Crops -21.38 8.21 +4.34 7.18 Food Crops -53.53 10.49 -18.73 9.63 Pasture -28.23 10.29 -19.25 7.55 Total Agriculture -103.14 28.99 -33.64 24.36 Percent Co- opted -- 50.09-- 42.09

12. 12 a. Deforestation b. Intensification -18 -16 -8 -4 -2 -1 1 2 4 8 kg C m -2 Effects of cellulosic biofuels on terrestrial carbon storage up to 2050

13. 13 a) Deforestation b) Intensification Carbon loans from land stocks and payback times over the 21 st century

14. 14 Summary Remarks Earth’s landscape could be fundamentally reshaped when and if we implement a global biofuels program. Land-use polices that protect specific biomes can have important positive consequences. Irrespective of these policies, however, there will almost certainly be massive biodiversity losses as biomass crops replace natural vegetation at the scale of 14 to 15 million km 2. Release of large amounts of carbon to the atmosphere possible – large enough to affect the climate system – especially if forested land is cleared for biofuel crops. This is like humanity taking a large carbon loan from the biosphere. Up to about 50% of the annual terrestrial NPP could be co-opted in 2050 due to the expansion of managed lands (currently about 30% is co-opted). The consequences for ecosystem services of such a large percentage of NPP being co-opted are unknown, but potentially critical. For example, we do not know if we will be crossing thresholds, beyond which the biosphere will function in different ways.

15. 15 Near-term Challenges Resource needs and unintended consequences –Nitrogen and N 2 O production –Water competition among uses Biodiversity consequences Social and cultural consequences

16. 16 Potential Hotspots of Biotic Impoverishment

17. 17 TEM/EPPA Linkage