Energy, Food and Climate in the 21st Century

Energy, Food and Climate in the 21st Century

by David Tilman
University of Minnesota
Global Population Projections
Developing Nations
Population Would
Increase by 2 Billion
Least Developed by 1 Billion
Global Per Capita Income Projections
Developed Increase
42%
Developing & Least
Developed Incomes
Would Increase
~380%
Per Capita Carbon Dioxide Emissions
Income Drives Energy Demand and Fossil
Fuel Greenhouse Gas Releases
Per Capita Income (1990 International Dollars)
Agricultural Food Production and
Greenhouse Gasses?
Agriculture Currently Accounts for ~35% of
Global Greenhouse Gas Emissions
Total Kcal Agricultural Demand
Projections of Total Agricultural Demand
(Kcal)
192%
150%
Global Cereal Yield Trends
If This Rate Of
Yield Gain Could
Be Maintained For
50 More Years,
Global Cereal
Yields Would
Increase By 70%
For a Weighted Mix of All Major Crops Combined, Global
Yields Are on Trajectory to Increase 66% in 50 Years
Crop Land Demand (hectares)
Projections of Crop Land Demand
180%
92%
Projected Yield & Global Food
Demand Increases
Would Require ~1.3 Billion Hectares
of New Crop Land (and more if all
nations had diets of
developed nations)
And, about 0.5 Billion More
Hectares of Pasture Land for Meat/
Dairy Production
Our Diet-Change Scenarios
IPCC Scenarios
Gigatons of C (as CO2) per Year
CO2 Released from
Forests and Soils
Because of
Land Clearing to
Meet Changing
Global Diets
Total Agricultural Demand
Projections of Total Agricultural Demand
(Meat, Milk Eggs)
340%
225%
Turn Food into Biofuels
Food-Based Biofuels Require New Land
Or Take Land From Food Crops
-----------------Biofuels produced by clearing intact native ecosystems ----------------------
Biofuels can be worse for climate change than gasoline
or diesel (Fargione, Hill & Tilman 2008 Science)
Greenhouse Gas Reductions for Next Generation Biofuels
Each Biomass Crop Will Have Its Own Optimal Conditions for Growth
Potential Solutions
to the
Food – EnergyEnvironment Trilemma
1. Invest in Higher Gains in Crop
Yields
1. Major investment in crop breeding for
cereals and non-cereal crops and meat
2. Infrastructure, seeds and technologies for
farmers of least developed nations,
especially in Africa where yields are 1/5
those of other similar regions
Increasing Yields
of Least Developed and Developing
Nations to Those of Developed Nations
Would Increase World
Global Food Supply by 80%
In combination with anticipated 70%
increase in yields,
essentially no new land would be needed
to feed the world in 2060
Eliminates massive GHG emissions
2. Eat Higher-Efficiency Animal
Protein and/or Less Animal Protein
Animal Species
Cattle (CAFO)
Pigs
Poultry
Fish aquaculture
Dry Grain : Usable Meat
12 kg/kg
6 kg/kg
2.5 kg/kg
1.0 kg/kg
Shifts in types or amounts of meat consumed can
cause large shifts in cereal demand and the
land and agrichemicals needed to produce it.
Agricultural Land Clearing Changes by
Shifting Our Diets
1. Same per capita animal protein as developed nations
but with 80% less beef+pork:
49% less new land needed
2. 20% less per capita animal protein with 80% less
beef+pork:
69% less new land needed