What can Ecologists tell us about Sustainability? Charles J. Krebs Institute for Applied Ecology University of Canberra
3 A Little History and Philosophy “the present increasing disruption of the global environment is the product of a dynamic technology and science which originated in the Western medieval world” (p.1207) White (1967) contrasted two views of man and nature: - a Christian and post-Christian view that humans should dominate nature - an ecological world view of the equality of all creatures which he attributed to St. Francis White, L., Jr. 1967. The historical roots of our ecologic crisis. Science 155: 1203-1207.
Outline of Talk Ecology to what purpose? What is sustainability? A triumvirate of problems: Agriculture Biodiversity Population The Politics of Ignorance Summary
Basic Principle # 1 The earth has physical, chemical, and biological limitations - it is the only planet we have
A Few Core Points Scientists do not make policy - provide evidence about issues Scientists expect rational decisions - evidence-based policies by governments Scientists must point out when business or government policies violate scientific knowledge - a moral obligation
What is Sustainability ? Brundtland Commission (1987) - sustainable development Now a ‘buzz’ word that is nearly meaningless The ecological meaning: to meet our present needs without compromising the needs of future generations The essential element is intergenerational equity
Basic Ideas for Sustainability The Precautionary Principle - look before you leap Protect your capital - biodiversity Hedge your investments - risk management Buy insurance - parks and reserves
Are Current World Practices Sustainable ? Three key areas - Agriculture - Biodiversity - Population Two steps for ecologists: - evaluate the current situation - suggest solutions to current problems
Two Broad Measures Ecological Footprint - what resources do people use? - convert these all to hectares - index against the world supply - 1960-2007 Living Planet Index - state of global biodiversity - based on vertebrate populations - 1970-2007 Butchart, S. H. M. et al. 2010. Global biodiversity: indicators of recent declines. Science 328:1164-1168.
The World’s Ecological Footprint Source: Living Planet Guide 2010
Living Planet Index Source: Living Planet Guide 2010 Based on trends in 7953 populations Of 2544 vertebrate species 28% drop
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?
Agricultural Sustainability - # 1 Ecological Generalisation # 1: ecosystems must run on solar energy - current agriculture runs on non- renewable resources (oil, natural gas, coal) Agriculture must transition to renewable energy - whither industrial agriculture?
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
Pimentel, D. (2009). Energy inputs in food crop production in developing and developed nations. Energies 2: 1-24. Output is 2.6 times input Output is 3.3 times input
Cerrato, M.E., and Blackmer, A.M. 1990. Comparison of models for describing corn yield response to nitrogen fertilizer. Agronomy Journal 82: 138-143.
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
Dery, P. and Anderson, B. 2007. Peak phosphorus. Energy Bulletin 13 August 2007. Production (Mg/year) Year World Rock Phosphate Production
Agricultural Sustainability - # 4 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
What is Biodiversity? Four levels of biodiversity: - molecular diversity - genetic diversity - species diversity - ecosystem diversity Species are the key unit in most discussions of biodiversity
Biodiversity Premise: biodiversity provides a planet that is inhabitable by humans - if this is correct, protecting biodiversity must become a major societal goal What principles of applied ecology are applicable to biodiversity conservation ?
A Basic Ecological Principle Biodiversity is useful for us - ecosystems provide services to the Earth and to humans - this is the utilitarian reason for protecting biodiversity
Ecosystem Services # 1 Purification of air and water Pollination of crops Decomposition of wastes Moderation of weather Pest control Prevention of soil erosion Aesthetic values for people
Ecosystem Services # 2 Some ecosystem services can be evaluated financially - pollination in agriculture Many ecosystem services are non-monetary - prevention of erosion I think it is a mistake to make an economic argument for the protection of biodiversity but most ecologists use economics to indicate importance
28 Ecosystem Services # 3 Some dollar figures for ecosystem services: - natural enemies suppress soybean aphids in 4 USA states – value US$ 239 million - natural pest control for all US crops valued at $ 13.6 billion per year - insect pollination value to the world’s food production estimated at US $ 100 billion - total for all services $33 trillion per year….. Power, A.G. (2010) Ecosystem services and agriculture: tradeoffs and synergies. Philosophical Transactions of the Royal Society B 365: 2959-2971.
Roubik, D.W. (2002) Tropical agriculture: The value of bees to the coffee harvest. Nature 417: 708. Coffee Yields and Insect Pollinators
30 Ecosystem Services # 4 Coda: - there is an ever growing literature about the value of 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 paper money….. Power, A.G. (2010). Ecosystem services and agriculture: tradeoffs and synergies. Philosophical Transactions of the Royal Society B 365: 2959-2971.
Photo courtesy of Dr. C.Picket, CDFA, USA Strips of flowering alyssum in California lettuce crops
Photo courtesy of Dr. C.Picket, CDFA, USA Strips of buckwheat sown between vine rows in New Zealand to provide nectar and pollen for beneficial insects
Biodiversity Problems We do not have an inventory of all the species on earth Most species are rare so they are difficult to study For many species that are described, we do not know if they are endangered or not Should we triage species we cannot easily save and invest conservation dollars wisely?
34 Biodiversity Solutions Set aside large areas and corridors as reserves and parks Protect these areas from human exploitation Monitor the populations of selected species Engender public and political support via sexy species Possingham, H.P. 2001. The business of biodiversity: applying decision theory principles to nature conservation. Environment, Economy and Society 9: 1-37.
Problem for Biodiversity Solutions No current national park or reserve is large enough for large species Off-reserve conservation is essential Climate change will change reserves Biodiversity solutions require money that is not available
Population Population dynamics is probably the best understood of all the subdisciplines of ecology - mathematics of population change - extensive experimental studies from many plants and animals What principles of ecology are applicable to our population crisis ?
An Ecological Principle No population increases without limit - there are no ecologists I know that doubt this law - the scientific argument about it is that it is an automatic consequence of the fact that the world is finite
Red Kangaroos – South Australia Pople, A.R. et al. (2010). Reassessing the spatial and temporal dynamics of kangaroo populations. In Macropods, ed. by G.Coulson and M. Eldridge. CSIRO Publishing. pp. 197-210.
Population Reference Bureau, http://www.prb.org/ 30 December 2010http://www.prb.org/ Human Population Growth – 1500 to 2010
Population Growth # 1 Two ways to stop population growth: 1.High birth rate = high death rate 2.Low birth rate = low death rate - no one advocates solution # 1 - if there is a ‘third way’ population ecologists have not discovered it in over 100 years of research
Population Growth # 2 But if this is correct….
Population Decline The human population must decline over the next 2 centuries 1.Birth rate < high death rate 2.Low birth rate < low death rate - no one advocates solution # 1 - solution # 2 is already underway!
Population Reference Bureau. 2010. World Population Data Sheet. http://www.prb.org/ http://www.prb.org/ Human Fertility Change – 1970 to 2010
The Bottom Line on Population The women of the world have already sent a message to their governments that they recognize that a population decline is desirable The governments of most of the western countries are not listening A few economists and business people are aware but they are drowned out by the growth-at-any-cost world view
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
Krebs, C.J. (2008) The Ecological World View. CSIRO Publishing, Collingwood, p. 508. Real state of the world Optimists correct Skeptics correct Current policies to be used in environmental decisions Technological optimists’ policies HighDisaster Technological skeptics’ policies GoodVery good Payoff Matrix
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 accumulating evidence that the ecological world view is slowly replacing the economic world view
Summary - # 1 Sustainability is an ecological concept that has been abused to become nearly meaningless Three critical world problems have their roots in ecology: - agricultural production - biodiversity conservation - human population growth
Summary - # 2 We must wean our world-view away from the simple idea that technological progress will solve all these problems Remember that infinite growth is the philosophy of the cancer cell and not a philosophy of sustainable land use For our children we should leave a world that is not diminished There is much progress in ecological understanding, but much yet to do