Natural Resources & Human Impacts
In our finalweek we integrate our understanding of human and physical geography. We address the natural resources critical to human society, climate change, and the human impact on the Bio-sphere.
No Slide Title Climate Change Updated 1/22/18 [This section supplemented by: Miller. 2001. Environmental science] Historical climatic change * Glaciation (ice ages): Louis Agassiz (1830s-1840s) * Modern evidence * Ice core data is a primary source of information re: the chemical composition the atmosphere in the past- bubbles of air trapped in the ice preserve ancientatmosphere- modern understanding of gas phase chemistry allows scientists to infer ancient temperature among other things * Foraminifera * Marine protist that secrets calcium-based shell * Certain species require certain temps., so the layering of fossil tests indicates past temperature * Oxygen isotopes * Modern seawater has fixed ratio of O16 & O18 isotopes * More O16 than O18 evaporates * In ice age, 16O gets stored in glaciers (does not return to ocean) * Analyze ancient bubbles in glaciers & oxygen in foraminiferan tests * Ice ages can develop and recede quickly (decades rather than millenia) --> probably positive feedback * Ice age begins: low temp -> more ice -> more sunlight reflected -> lower temp * Threshold: too cold for evaporation -> reduced snowfall -> ice begins to melt * Ice age recedes: ice begins to melt -> exposed Earth absorbs sun -> more melting * Most recent ice age began to recede 9,000 - 18,000 years ago B. Causes of climatic change 1. Variation in Earth's orbit (Milankovitch effect) * Eccentricity (100,000-year cycle): orbit changes from ellipse to circle (vary distance from Sun) * Obliquity (41,000-year cycle): Earth's tilt varies b/w 22° & 24.5° (vary direct sunrays in summer & oblique rays in winter) --> Can predict onset of ice age (Earth should be in full ice age by 23,000 years from now) 2. Variation in solar output: 11-year "sunspot" cycle of maximum output (sunspots) 3. Variation in Earth's atmosphere: volcanic ash, greenhouse gases 4. Variation in ocean circulation (currents & vertical mixing): affect climates on land 5. Continental drift: large ancient continents affect wind & ocean circulation, and absorption of solar energy by Earth 1900 (Weare. 2002. Calif. Agric. 56: 89-96) Black Death (1347-1351) * Recent global temperature increases are unable to be accounted for with any combination of these natural climate forcings. 1. Variation in Earth's orbit: 2. Variation in solar output: 3. Variation in ocean circulation: 4. Continental drift: very unlikely * Recent changes can be accounted for when human greenhouse gas emissions are included in models. 10 miles (16 km) troposphere C. Greenhouse effect & global warming * greenhouse effect: natural warming of the lower atmosphere (troposphere); Arrhenius (1896). water vapor H2O carbon dioxideCO2burning fuel ozoneO3vehicles methaneCH4 anaerobic resp. nitrous oxideN2Ofertilizer CFCs (chlorofluorocarbons)coolant; aerosol light heat (IR) UV waste E (heat) greenhouse molecules absorb then emit heat Global warming * increase of greenhouse gases in troposphere leads to greater heat retention * expected to increase global temperature * unnatural or human enhanced greenhouse effect Have greenhouse gases increased? * Last ~50 years of direct measurements of atmospheric concentrations of CO2. * Notice the seasonal variation when plant growth partly offsets rising CO2 levels on a seasonal basis. [CO2] Have greenhouse gases increased? * Historic gas content: bubbles in ancient ice (650,000 ya) * Last ~50 years: [CO2] There is a Scientific consensus that human carbon dioxide emissions are significant in recent climate change. This consensus has been pretty solid for over 25 years. There is also some public controversy which is largely unrelated to scientific evidence and conclusions. This chart shows ice core and direct measurements of atmospheric CO2 levels. Today’s carbon dioxide level of (408 ppm) is almost 130 ppm higher than it has been in the last 650,000 years! Recent ice core data is extending this conclusion back for 1 million years. Atmospheric concentration of CO2 and other greenhouse gases continues to climb. As of January 2018 CO2 had reached 408 ppm How might average global temperature change? * 1995 IPCC (Intergovernmental Panel on Climate Change): 2 - 7° F (1 - 4° C) * 2002 IPCC: 4 - 12° F (2 - 7° C) * 2° C: greater than anything that has occurred in past 10,000 years. * 3° C: greater than anything that has occurred in past 1,000,000 years. * Temp. change largely due to minimum nighttime temp's increasing * Fewer cold/frost days 1900 2000 # frost days plants in Switzerland (Walther. 2000. Phytocoenologia 30: 409-430) # non-native species Global average temperatures are increasing over land and throughout the ocean and other water bodies. Ecological signals of climate change (Walther et al. 2002. Nature 416: 389-395) * Retreat of glaciers/snow on mountains * Phenology (timing of seasonal activities) of spring events over last 20-60 years * Flowers and leafs unfold ~2 days earlier per decade * Butterflies appear ~3 days earlier per decade * Birds migrate and breed ~3 days earlier per decade * Range shifts * Mountain plants & birds shift up mountain * Birds & butterflies shift towards poles Possible effects of global warming * Inc. water evaporation --> more precipitation in some areas (with more flooding) * In areas without increased precipitation --> evaporation of fresh water sources * Inc. clouds --> might bring more warming (trap heat) or more cooling (reflect sunlight) * More rain & run-off + warm water expands --> sea level rise (0.5 - 3 feet by 2100) * If polar ice melts, even larger rise in sea levels (rose 300 feet at the end of last Ice Age) * Warming of ocean releases more CO2 into air + input of fresh water from polar ice (less photosynthesis by phytoplankton) --> CO2 levels in atmosphere remain high -> accelerate global warming Possible effects of global warming (cont'd) * Warm climate spreads towards poles * Possible inc. food production, depending upon soil & farming infrastructure * Spread of tropical diseases * Restructuring of ecological communities * Weather extremes increase in intensity and frequency (eg. heat waves, storms) * Can organisms respond in time? Physical tolerance vs. dispersal ability & habitat availability * Humans: "environmental refugees" (esp. coastal flooding); perhaps 50-150 million by 2050 (cf. 7 million after WWII) Solutions: dealing with global warming Prevention; slowing Clean-up; treatment * Reduce fossil fuel use * Slow pop growth * Efficiency (use less E): jobs, money, preserve resources, reduce pollution * Cleaner Energy sources * Stop or slow air pollution (smog,acid rain) * Adapt circular economic principles, reduce waste * Reduce deforestation * Remove CO2 from emissions * Plant trees: young trees have high photosynthesis rates (take CO2 from air) * Preparation * Develop crops that need less water * Move human activities away from current coasts * Stockpile food * Expand wildlife preserves towards poles Renewable energy sources Net heatEnv. costGen. costProsConsCO2 Solar1 - 68 - 16Free; clean; low impactNeed access to sunNone (heating)Currently expensive & unsightly SolarModerate impactLow efficiencyNone (elec.)Expensive Solar0.430Low impact Low efficiency None cells Expensive Water5EfficientHigh impactNone Water for other uses(w/out decay) Geo-0.15 thermal Wind0.16Efficient; low impactNeed a lot of turbinesNone Biomass0.75SimpleEcosystem degradeLo HydrogenClean; can be efficientCurrently expensiveNone Resources "Ecosystem services" Renewable physical processes (solar energy, wind, geothermal, moving water) Potentially renew Biosphere (organisms) Nonrenewable Lithosphere (fuels, minerals) human use human waste physical processes (air & water circulation) physical & biotic processes (soil formation, chemical cycling, waste detox., pest control) sustainability: depleting resources while allowing for their renewal and not degrading ecosystem services. Natural capital Solar capital 99% of energy 1% Worldviews 1. Do we have a significant impact on the planet? 2. Are we adversely affecting ... a. resource abundance? (non-renewable and potentially renewable) b. ecosystem services? No (nihilism) Yes No (always more; present practices OK) Yes No (self-cleaning; present practices OK) Yes 3. Should we change how we use the planet's natural capital (resources & services)? No (abundant, self-cleaning planet; present practices OK) Don't worry, we'll fix any problems (humans are clever; humans cannot perish) Yes, we're making a mess (self-interest; responsibility for mess; care for biodiversity/Earth) Null hypothesis: there is nothing wrong with how we currently utilize the planet's natural capital. Null hypo is true Null hypo is false Do not reject null: do not change Reject null: change current practices Continue economic trend Eventual environmental disaster Affect economic trend Affect economic trend; environmental improvement Type I error Type II error TRUTH (unknown in this case) Precautionary principle: * when faced with uncertainty about a system, or with the risk of a harmful outcome, policy should reduce risk to the resource, environment, and people. * "Better safe than sorry." * fisheries management (Garcia 1996) Legal case -- Null hypothesis: innocent. Null hypo is true Null hypo is false Do not reject null: "not guilty" Reject null: "guilty" Innocent, not convicted Guilty, not convicted Innocent, convicted Guilty, convicted Type I error Type II error TRUTH (known by the defendant) jury Major environmental challenges Causes Rapid population growth Little emphasis on pollution/waste prevention Little emphasis on value of intact ecosystems Little emphasis on energy efficiency Poverty Effects Resource depletion; ecosystem degradation Industrialized agriculture: soil erosion & damage Air pollution: global warming, ozone depletion, acid rain Water pollution Environmental= PopPer capita Degradation/ impactresourcepollution per useresource use IP AT Working towards solutions to environmental challenges * Increased resource conservation (efficiency, recycling), not use * Pollution & waste prevention, not clean-up * Preserving natural capital (genetic & species diversity; intact ecosystems) * Economic shifts (full-cost pricing, redirecting subsidies & taxes) * Reduce poverty (debt relief, foreign aid, small loans) * Recognize emerging environmental impact of developing nations * Reduce population growth * Individual questions: How much do I want? How much do I need? How do my use and disposal of goods affect the environment? Are we making progress? Population growth * World pop growth has slowed by ~50%, ... but ~8 billion by 2028. * % of world's hungry dec., ... but ~25% malnourished or worse. Resource depletion; ecosystem degradation * Industrial countries inc. forest cover, ... but are planted, simplified systems. * Tropical deforestation ... continued loss threatens biodiversity. * Fossil fuel prices dec., reserves inc., ... but result in degradation & pollution. Agriculture: improved methods for soil conservation, ... but net erosion for ~33% cropland. Fertilizer, pesticide, & herbicide runoff problematic ecologically Air pollution: global warming, ozone depletion, acid rain * Public controversy over climate change in spite of solid scientific consensus * Ozone depleting chemical emissions reduced- some recover in ozone layer * Clean energy use inc. (solar call boxes), ... but subsidy-backed fossil fuels dominate. Water: dams & surface transfer can meet water demands, ... but unequal distribution (~20% lack