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A Global-Scale Biofuels Program and its Environmental

Consequences

J. Melillo1, A. Gurgel2, D. Kicklighter1, J. Reilly2, T. Cronin1, S. Paltsev2, B. Felzer1,

A. Sokolov2 and X. Wang2

1 The Ecosystems Center, MBL, Woods Hole, MA

2 Joint Program on Global Change, MIT, Cambridge MA

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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

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MIT Integrated Global

System Model (IGSM)

Prinn et al., 1999, Climatic Change, 41(3/4), 469-546.

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• 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).

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Terrestrial Ecosystem Model (TEM)

Melillo et al. 1993, Nature 363: 234-240; Felzer et al. 2004 Tellus, 56B, 230-248

6Crop yield

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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 [CO2] 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)

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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

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Absolute land areas in different land uses (million km2)

Contemporary Deforest. Intensif.

2000 2050

Total Land Area of the Earth

133 -----------------------------------

Total Area Co-opted for Human Use

42 59 50

Biofuels Area 0 15 14

Crop Area 16 20 18

Pasture Area 26 24 18

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a. Deforestation

b. Intensification

0 10 20 40 60 80 100

Percent

% of grid cell (0.5x0.5o) in biofuels

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Preliminary Simulation Results

Deforestation Scenario Intensification Scenario

Land Cover ΔCarbon(Pg C)

Co-opted NPP(Pg C yr-1)

ΔCarbon(Pg C)

Co-opted NPP(Pg C yr-1)

Time Period 2000-2050 2040-2049 2000-2050 2040-2049

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

TotalAgriculture

-103.14 28.99 -33.64 24.36

Percent Co-opted

-- 50.09 -- 42.09

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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

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Year

2000 2010 2020 2030 2040 2050

Car

bon

Bal

anc

e (

Pg

C)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

Direct EffectsDirect and Maximum Indirect Effects

a) Deforestation

Year

2000 2010 2020 2030 2040 2050

Car

bon

Bal

ance

( P

g C

)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50b) Intensification

Carbon loans from land stocks and payback times over the 21st century

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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 km2.

• 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.

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Near-term Challenges

• Resource needs and unintended consequences

– Nitrogen and N2O production

– Water competition among uses

• Biodiversity consequences

• Social and cultural consequences

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Potential Hotspots of Biotic Impoverishment

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TEM/EPPA Linkage

C urrentB iofuels

Map

E conomic Model

(E P P A)

Maps ofC limate

Variables

NP PMap

T E M

F utureB iofuels

Map

C urrentB iofuels

Map

E conomic Model

(E P P A)

Maps ofC limate

Variables

NP PMap

T E M

F utureB iofuels

Map