Is Modern Agriculture Sustainable? An Ecologist’s View of Agricultural Science Charles J. Krebs Department of Zoology University of British Columbia Outline of Talk Ecology to what purpose? A triumvirate of problems: Agriculture – Biodiversity - Population Ecological principles for guidance in helping to solve the agricultural crisis Summary Ecological understanding Management recommendations Policy implementation The Politics of Ignorance Basic Principle # 1 The earth has physical, chemical, and biological limitations - it is the only planet we have Are Current World Practices Sustainable ? Three key areas - Agriculture - Biodiversity - Population Two steps for ecologists: - evaluate the current situation - suggest solutions to current problems Global Distribution of Hunger: Quantified by the 2012 Global Hunger Index Wheeler, T. and J. von Braun. 2013. Climate change impacts on global food security. Science 341:508-513. Global Yield Trends in Rice and Wheat 10 target Yield (tons per ha) 8 % 2.4 6 er y p % 1.0 4 pe e ry ar target ear Rice er ye 0.9% p 2 ar Wheat 0 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Ray, D. K. et al. 2013. Yield trends are insufficient to double global crop production by 2050. PLoS ONE 8:e66428. Global Agricultural Land Area Land area (km2 x 106) ha 6 Total Agricultural Area 5 4 Meadows and Pastures 3 Since 1991 no change in land area used 2 Arable Land and Crops 1 0 1970 Source: FAOSTAT, 2013. 1980 1990 2000 2010 Five Solutions Stop expanding agriculture’s footprint Close the world’s yield gaps Use resources more efficiently Shift diets away from meat Reduce food waste Foley, J. A. 2011. Can we feed the world and sustain the planet? Scientific American 305 (5): 60-65. Maize Yield in Africa Cropland Currently operating at 10-30% of potential tonnes per ha Yield in 2000 Potential Yields Under optimum use of rainwater, nutrient, weed, and disease management Bindraban, P. S. et al. (2012). Assessing the impact of soil degradation on food production. Current Opinion in Environmental Sustainability 4:478-488. Agriculture Premise: Agriculture is applied ecology - if this is correct, agriculture must operate under the principles of applied ecology What principles of applied ecology are applicable? Agriculture – Fundamental Issues Agriculture reduces biodiversity - is this reversible? Agriculture exacerbates climate change - can we neutralize this? Agricultural Sustainability - # 1 Ecological Generalisation # 1: ecosystems must run on solar energy - current agriculture runs on nonrenewable resources (oil, natural gas, coal) Agriculture must transition to renewable energy - whither industrial agriculture? Agricultural Sustainability - # 1 Agriculture can continue to use nonrenewable resources only if it can remove their harmful effects on the air, water, and land This is a very important technical problem in energy engineering that is beyond my expertise to discuss Agricultural Sustainability - # 2 Ecological Generalization # 2: nutrient input = nutrient output - crop production depends on fertilizer inputs Nitrogen limits productivity in many soils Phosphate is also required in fertilizer Fertilizer Problems - # 1 Nitrogen is both a positive and a negative factor - crop production depends on fertilizer inputs - biodiversity declines with nitrogen inputs - water pollution results from excessive nitrogen runoff Global nitrogen fixation, natural and anthropogenic, for 2010 Biological Nitrogen Fixation Fowler, D., et al. 2013. The global nitrogen cycle in the twenty-first century. Philosophical Transactions of the Royal Society of London B: 368: doi 10.1098/rstb.2013.0164. Effects of Nitrogen Fertilizer Input on Plant Biodiversity in Europe No. of plant species per 100 m2 80 70 60 50 more nitrogen fertiliser = fewer plant species 40 30 20 10 0 0 50 100 150 200 250 300 350 400 450 Annual Nitrogen input (kg/ha/year) Kleijn, D. et al. (2009). On the relationship between farmland biodiversity and land-use intensity in Europe. Proceedings of the Royal Society of London B 276:903-909. Corn Yield - Iowa Corn grain (tonnes per ha) 12 10 8 6 4 0 50 100 150 200 250 300 Nitrogen fertilizer - kg/ha Cerrato, M.E., and Blackmer, A.M. 1990. Comparison of models for describing corn yield response to nitrogen fertilizer. Agronomy Journal 82: 138-143. 350 Agricultural Sustainability - # 3 Fertilizer - nitrogen is produced from natural gas - phosphate comes from rocks Nitrogen production is tied to oil in availability and price Phosphate is limited to rock formations World Rock Phosphate Production Production (Mg/year) Peak phosphorus ≈ Peak oil Year Dery, P. and Anderson, B. 2007. Peak phosphorus. Energy Bulletin 13 August 2007. World Phosphorus Fertilizer Use 50 Million tons P2O5 40 1.8% growth 30 4.6% growth 20 10 0 1960 1970 1980 1990 2000 2010 Cordell, D. and S. White. (2011). Peak phosphorus: Clarifying the key issues of a vigorous debate about long-term phosphorus security. Sustainability 3:2027-2049. Phosphorus - # 1 An essential element for all living organisms Renewable P from bird guano - Nauru, Christmas Island, now gone Non-renewable P from igneous and sedimentary rocks - Morocco, China, USA mainly - a finite resource Scholz, R. W., and F.-W. Wellmer. 2013. Approaching a dynamic view on the availability of mineral resources: What we may learn from the case of phosphorus? Global Environmental Change 23:11-27. Phosphorus - # 2 Will we run out of phosphorus? Quality and accessibility of remaining reserves are decreasing - costs will thus increase Extremely variable estimates of how much phosphorous is left in rocks Neset, T.-S. and D. Cordell. 2012. Global phosphorus scarcity: identifying synergies for a sustainable future. Journal of the Science of Food and Agriculture 92: 2-6. Lifetime of World Phosphate Rock Reserves Author Estimated Estimated year lifetime of of depletion Assumptions reserves Tweeten (1989) 61 years 2050 3.6% increase in demand Runge-Metzger (1995) 88 years 2083 2.1% increase in demand 60-130 years 2058-2128 2-3% increase in demand Smil (2009) 80 years 2080 At current rate of extraction Fixen (2009) 93 years 2102 At 2007 production rate 69-100 years 2078-2109 90 years 2099 At current rates 300-400 years 2310-2410 At current rates Steen (1998) Smit et al. (2009) Vaccari (2010) Van Kauwenbergh (2010) 0.7% to 2% increase to 2050 Cordell, D. and S. White. (2011). Peak phosphorus: Clarifying the key issues of a vigorous debate about long-term phosphorus security. Sustainability 3:2027-2049. “If ‘Plateau Phosphorus’ does describe future production, the new reserve figures could add 168 years to production availability.” Mew M. Future phosphate rock production – peak or plateau? Retrieved June 12, 2012, from http://www.fertecon-frc.info/page15.htm Phosphorus - # 3 Does the “Peak Phosphorus” curve apply to future supplies? The analogy with oil production is not valid because oil can be substituted by other energy sources There is nothing known that can substitute for phosphorus Scholz, R. W. and F.-W. Wellmer. (2013). Approaching a dynamic view on the availability of mineral resources: What we may learn from the case of phosphorus? Global Environmental Change 23:11-27. Phosphorus - # 4 There is a limited amount of phosphorus available on the Earth - everyone seems to agree on this Recycling and recovery must be part of the phosphorus management strategy There are now movements in this direction Rhodes, C. J. 2013. Peak phosphorus - peak food? The need to close the phosphorus cycle. Science Progress 96: 109-152. Agricultural Sustainability - # 4 Soil erosion is a critical problem that is a central issue in nutrient losses What is the state of soil erosion in agricultural areas? Soil Degradation Penalty for Food Crops in China Business as usual 2030 Double soil Degradation 2030 Food production decline of 14% to 30% Business as usual 2050 Double soil Degradation 2050 Ye, L. and E.Van Ranst. (2009). Production scenarios and the effect of soil degradation on longterm food security in China. Global Environmental Change 19:464-481. Agricultural Sustainability - # 5 Climate change is happening Four broad impacts on agriculture: - changes in the distribution of rainfall and temperature - increased variability of weather - changing crop productivity (C3, C4) - coastal crops and sea level rise Soils do not move…. Rising CO2 Levels Increasing CO2 increases the yield of C3 crop plants Increasing CO2 does not increase the yield of C4 crop plants Drought stress can be reduced in C4 plants because of lower stomatal conductance Leakey, A. D. B. 2009. Rising atmospheric carbon dioxide concentration and the future of C4 crops for food and fuel. Proceedings of the Royal Society B: 276:2333-2343. Percentage of agricultural land used for the production of C4 crops in 2006 Main C4 crops are maize, sugar cane, millet and sorghum Leakey, A. D. B. 2009. Rising atmospheric carbon dioxide concentration and the future of C4 crops for food and fuel. Proceedings of the Royal Society B: 276:2333-2343. Change in Cereal Production and Population Growth, 1970-2010 cereals End of the Green Revolution people Source: FAO Agricultural Sustainability - # 6 Solutions - recycle nutrients - reduce fossil fuel use - low tillage, organic agriculture? - develop better crops, diversify - improve grazing management - integrate crops and livestock - stop using food for biofuels - invest in agriculture Agricultural Sustainability - # 7 What should you eat? Ray Hilborn and his research group have computed the environmental impact of animal foods 213 studies, 16 production technologies, 9 measures of impact Life Cycle Assessments Hilborn, R., J. Banobi, and S. J. Hall. 2014. The environmental cost of animal source foods. Proceedings of the National Academy of Sciences USA (in review). Energy Used In Production Energy (MJ per 40 g protein better worse Aquaculture Capture fisheries Livestock Hilborn et al. (2014) PNAS best for milk, worst for catfish aquaculture Greenhouse Gases outputs Greenhouse Gas output (Kg CO2 per 40 g protein better worse Aquaculture Capture fisheries Livestock Hilborn et al. (2014) PNAS best for molluscs, worst for beef production Agricultural Sustainability - # 8 What should you eat? Rank all food groups by 9 measures: - energy - greenhouse gases - acidfication - eutrophication - land used - water used - pesticides - antibiotics - soil loss Hilborn, R., J. Banobi, and S. J. Hall. 2014. The environmental cost of animal source foods. Proceedings of the National Academy of Sciences USA (in review). Agricultural Sustainability - # 8 What should you eat? Rank all food groups by 9 measures: - energy - greenhouse gases - acidfication - eutrophication - land used - water used - pesticides - antibiotics - soil loss Hilborn, R., J. Banobi, and S. J. Hall. 2014. The environmental cost of animal source foods. Proceedings of the National Academy of Sciences USA (in review). Environmental Impacts of Food Groups Beef Chicken Catfish Pork Eggs Shrimp Tilapia Carp Milk Finfish Invertebrates Salmonids Whitefish Large pelagics Snall pelagics Shellfish worse better 0 2 4 6 8 10 12 14 16 Average Rank Hilborn, R., J. Banobi, and S. J. Hall. 2014. The environmental cost of animal source foods. Proceedings of the National Academy of Sciences USA (in review). Agricultural Sustainability - # 9 The Bottom Line: What should you eat? Food security for the Earth would be improved if we ate more vegetables Even with this change, there are many problems that need addressing For any meat consumption, the devil is in the details, e.g. milk (good for energy, poor for water use, antibiotics, soil) Biodiversity Premise: biodiversity provides a planet that is inhabitable by humans - if this is correct, protecting biodiversity must become a major societal goal Biodiversity – Constraints We do not have a description of the existing life on earth We have a rudimentary understanding of how ecological communities operate Land clearing for agriculture has been a major cause of biodiversity loss - yet we need more food Ecosystem Services Coda: - there is an ever growing literature about the value of biodiversity and ecosystem services - much of this discussion is good political ecology but hopeless scientific ecology - we should protect biodiversity because we cannot eat iron ore or coal or phosphate rock or paper money….. Power, A.G. (2010). Ecosystem services and agriculture: tradeoffs and synergies. Philosophical Transactions of the Royal Society B 365: 2959-2971. 45 The Population Problem o Ecological Generalization # 3: - no population increases indefinitely o The human population of the Earth now exceeds the carrying capacity of the planet o Bringing the human population back to some sustainable level is a critical social issue Global Ecological Footprint 1.8 Fraction of the planet being utilised 1.6 1.4 1976 1.2 1.0 Carrying capacity of the Earth 0.8 0.6 0.4 0.2 0.0 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Source: Living Planet Report 2010 Year The Politics of Ignorance Operational Principle: what you do not know cannot hurt you - you can operate in this state by ignoring evidence-based science, or - you can fail to fund the scientific research that will shed light on specific problems The Politics of Ignorance # 2 Major current example: climate change - “there is no need to do anything until we have scientific certainty” - how should we respond to scientific uncertainty ? - technological optimists vs. technological pessimists The Bottom Line Scientists do not make policy But we know a great deal about the natural world that should inform policy but is not used We must continue to do good science and ask our governments to use evidence-based policies There is some hopeful evidence that the ecological world view is slowly replacing the economic world view Summary - # 1 Three critical world problems have their roots in ecology: - agricultural production - biodiversity conservation - human population growth Our job as scientists is to recognize the connections between these three problems and to work toward ethical solutions Summary - # 2 There is encouraging signs that we are moving in the direction of sustainability but perhaps more slowly than scientists would like Agricultural scientists are the heros of our day and should continue to lead the way to sustainable agriculture and human betterment - (I will not list who the bad guys are…) Thanks for listening !