Energy, Food and Climate in the 21st Century
Transcripción
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