Global Environmental Issues ENVRE 115 Oct. 16, 2007
Announcements • Assignment #3 posted- due Oct. 23 • Graduate Student Projects • Require topic approval by Tues., Oct. 30th • Make appointment to meet with Molly or Kazi • Scheduling a midterm review session
Agenda • Ecological Footprint • Introduction to Ecology • Drivers of environmental issues • Linkages between ecosystem & human well being
Ecological Footprint Definition A measure of the amount of biologically productive land and water area a human population requires to produce the resources it consumes and to absorb its wastes under prevailing technology for a given year.
Class of 2007 Question 1 How many biologically productive acres are required for your food? • less than 2 • 2 – 3 • 4 – 5 • 6 – 7 • 8 - 9 • more than 9
Class of 2007 Question 2How many biologically productive acres are required for your mobility? • less than 2 • 2 – 3 • 4 – 5 • 6 – 7 • 8 – 9 • 10 - 11 • 12 - 13 • more than 13
Class of 2007 Question 3How many biologically productive acres are required for your shelter? • less than 2 • 2 – 3 • 4 – 5 • 6 – 7 • 8 – 9 • 10 – 11 • more than 11
Class of 2007 Question 4How many biologically productive acres are required for your goods/services? • less than 2 • 2 – 3 • 4 – 5 • 6 – 7 • 8 – 9 • 10 – 11 • more than 11
Class of 2007 Question 5If everyone lived like you, how many planets would we need? • 1 • 2 • 3 • 4 • 5 • 6 • more than 6 This means it takes 36 more months for the Earth’s ecosystems to regenerate what we are using in a single year.
Global Human FootprintAs of 2003, exceeded the Earth’s biocapacity by ~25% (WWF) For how long can this go on? • Humanity’s demand will be twice the biosphere’s productive capacity in 2050 • A moderate business-as-usual scenario, based on United Nations projections of slow, steady growth of economies and populations
Introduction to Ecology Ecosystems Drivers Carrying Capacity Overshoot
Ecosystems • The complex interaction of plant, animal, and microbial communities and their associated non-living environment • Includes biochemical cycles (carbon, nitrogen, water, …) • Have no fixed size - boundaries are based on the scientific, management, or policy question being examined
Biomes • Biome - aggregate of ecosystems with similar biological, climatic, and social demands 9 Terrestrial Biomes + 2 Marine Biomes
Biosphere – the global ecosystem • The sum of all the planet’s ecosystems • Isolated in space, the biosphere is self-contained or closed except that photosynthesizers derive energy from sunlight and heat is lost into space
Impact From Human Activity • The ecosystems most altered by human activity • Marine • Freshwater • Temperate broadleaf forests • Temperate grasslands • Mediterranean forests • Tropical dry forests • The majority of the ecosystem conversion was to cultivated systems
What makes it global? • Local Commons • Urbanization • Water supply and sanitation • Human health • … • Regional Commons • Airsheds • Watersheds • Land and forests • Industrialization • Transportation corridors • Agriculture and other land uses • … • Global Commons • Oceans • Atmospheres • Minerals and materials • Climate • Globalization of trade and commerce • Global social and political institutions • Epidemics • …
Alter Structure, Alter Function • Altering the structure of an ecosystem (habitats or species) can influence the services provided by a particular ecosystem Agriculture Nitrogen & Phosphorous cycle • Fisheries
Lake Pepin is a large natural impoundment of the Mississippi River downstream from the Twin Cities. It is experiencing two major problems: (1) increased sediment ; and (2) increased phosphorus levels. The likely cause is an increase in row-crop acreage in Minnesota.
Nutrients & Algal Blooms Phosphorus entering Lake Pepin can lead to excessive algae growth, particularly severe in dry, low-flow years such as 1988. The Minnesota River Basin contributes the majority of phosphorus loads from non-point sources.
Fish Kills When algae die and decompose, they consume large amounts of oxygen. The dissolved oxygen can become critically low causing localized fish kills in Lake Pepin. Biological Oxygen Demand (BOD) of Lake Pepin is exceeded.
Northern Gulf of Mexico/Mississippi Delta showing deoxygenated (hypoxic) coastal water (light blue). This is due to excessive nutrients being washed into the sea. Source: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC, Jan 2003
Impacts of Hypoxic Zone • Reduce food resources for fish and shrimp • Reduced abundance of fish and shrimp • Decline in shrimp catch and catch efficiency • Loss of production potential due to the blocked migration of juvenile shrimp offshore by the presence of hypoxic zone • Increased abundance of Pseudo-nitschia diatoms (several species produce domoic acid) • Mississippi Watershed is a slow timescale– will take decades to reach a sustainable nitrogen & phosphorous cycle Diaz & Solow, 1999
Marine Hypoxic Zones Sources: Boesch 2002, Caddy 2000, Diaz and others (in press), Green and Short 2003, Rabalais 2002
A Civilization in Trouble and Exciting New Options Not every collapse has an environmental origin, but an eco-meltdown is often the main catalyst. Scientists suspect we have entered a time of global change swifter than any human being has ever witnessed. Where are we headed? What can we do to alter this course of events? The vast majority of scientists agree that global warming is real, it’s already happening and that it is the result of our activities and not a natural occurrence. The evidence is overwhelming and undeniable.
Ecological Carrying Capacity • Ecological definition: • the number of individuals in a population that the resource of a habitat can support • Other definitions: • Point at which the birth rate equals the death rate • The number of individuals an environment can support without significant negative impacts • The population size is constrained by whatever resource is in shortest supply • Have humans reached the carrying capacity?
Reaching the Carrying Capacity In 1944, 29 reindeer were introduced to St. Matthew Island. In 1963, there were 6,000. One winter later, there were less than 50. Klein, 1968
Overshoot • A rapidly growing population can exceed (overshoot) the ecological carrying capacity due to the “momentum” of its growth. • Indicators of Overshoot • Deterioration in renewable resources • Rising levels of pollution • Growing demands by military and industry to secure resources • Investment in human capital postponed to meet immediate consumption demands • Rising debt • Eroding goals for health and environment • Growing instability in natural ecosystems • Growing gap between rich and poor
Collapse of northern cod fishery – estimates of stocks to high • Renewable resource management – harvesting crops without damaging the resource • Maximum sustainable yield – harvest at a level that produces a consistent yield without forcing a population into decline
What is causing ecosystem change? • Direct Driver- influences ecosystem processes • Habitat change • Over-exploitation • Invasive alien species • Pollution • Climate change • Indirect Driver-collectively these drivers influence the level of production & consumption of ecosystem services • Population changes • Economic activities • Socio-political/Governmental factors • Cultural factors • Technological changes
Human population growth, if unchecked, increases in a geometrical ratio and the subsistence of man increases in an arithmetic ratio Human population growth is the incentive to develop new technology that will lead to development that diminishes population pressures Malthusians vs CornucopiansPerceptions of population pressure
Cornucopian Paradigm • We can solve any problem • Progress happens because of economic growth which will eventually raise the standard of living for all people • Benign Demographic Transition will happen as people decide to have fewer children
Malthusian (Ecological) Paradigm • Human population size is ultimately limited by food supply and/or other factors such as disease • Food supply is increased by additional capital, which in turn, requires more resources • There are natural limits for essential resource that will ultimately constrain human economics • Demographic Transition will not be benign
The Precautionary Principle • Asserts there is a 'premium' on a cautious and conservative approach to human interventions in the natural environment where our understanding of the likely consequences is limited and there are threats of serious or irreversible damage to natural systems and processes. Myers 1993 in Barbier, Burgess and Folke 1994, p.172.
Three Laws of Human Ecology • First Law: “We can never do merely one thing” • Nature is inter-connected • Second Law: “There's no away to throw to” • Ecosystems recycle all elements- so any waste is actually a resource • Third Law: The impact of any group or nation on the environment is represented qualitatively by P*A*T postulated by Garrett Hardin
Ehrlich Identity • Recognizes that growth in population, affluence, and technology are jointly responsible for environmental problems I = P * A * T Where, I=environmental impact P=population A=affluence T=technology
Utility of the Ehrlich Identify • Lead in the environment From 1946 to 1968, • US pop. increased 42% • Vehicle mile per capita doubled (100% increase) • The amount of lead per vehicle mile increased 81% • I = 414% increase in environmental lead concentrations
Role of Technology • Technology has been cast as both villain and hero • Using the same scenario, if we wanted to keep the environmental impact at the 1946 level, i.e. no increase in environmental lead, what technological improvement would need to be made? (1+0) = (1.42)*(2.0)*(1+.T/T) 1 = 2.84 *(1+.T/T) 1/2.84 = 1+.T/T .36 = 1+.T/T .36 – 1 = .T/T -.64 or -64% would have required changes in the method of production of vehicle miles such that emissions per mile fell by 64%
Consumer Preferences • Increasing wealth changes pattern of demand and ability to afford reducing externalities • Kuznets curve illustrates the relationship between economic development and environmental degradation
Climate change and human health: risks and responses Eds. A.J. McMichael et al.World Health Organization, Geneva 2003
Human Ecology Summarized • Ecology at its basic level is about organisms and the most limited essential resource (carrying capacity) • Humans are able to trade for natural resources and different living standards by formulating I=PAT (technology) • Human influence their environment but the environment influences human behavior (consumption) • Natural resources have become a fungible commodity • Can efficient technology stretch natural resources so we can achieve a benign demographic transition?
Investing in Ecosystems for Pro-Poor Development Case Analysis Prepared by: Simon Zbinden and David R. LeeMay 3, 2003 Conference on Reconciling Rural Poverty Reduction and Resource Conservation
Forestry • Ecological Function of Forests • regulate the water cycle • stabilize soils • moderate climate by fixing carbon • provide habitat for flora and fauna • offer cultural, spiritual, and recreational opportunities • provide food, medicines, and wood