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Final

Final review + book notes(you can ignore these Chinese translations).docx

31 Pages
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Department
Environmental Studies
Course Code
ENV1101
Professor
Sonia Wesche

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Human need for nature – physical • ecosystem services • other physical benefits • outdoor recreation • “green exercise” … – social/relational • Human to human relations – children – adults • Human to nature contact – intangible无无无 • genetic - biophilia • developmental • educational • spiritual Biophilia: the concept that human beings subconsciously 潜潜潜潜seek a connection with the rest of life • innate need to connect with other life forms and the living world around us • essential to – our development – our well-being • loss of contact … consequences – children • contact with nature … regular play in a natural environment helps children – reach their full potential – develop • motor skills • awareness, observation • creativity, imagination, sense of wonder • social and communication skills • independence, individual identity Nature Deficit Disorder • Last Child in the Woods: Richard Louv (2008) • Children’s lives have moved indoors – Car transport (almost everywhere) – Experience nature through windows and on screen • Coined term “Nature Deficit Disorder” A lack of routine contact with nature may result in stunted academiThis unwanted side- growth.  effect of the electronic age is calledture Deficit Disor. The term was coined by author Richard Louv in his book Last Child in the Woods in order to explain how our societal disconnect with nature is affecting today's children. Chap 14. Atmospheric 潜潜潜潜 Science and Air Pollution -Hillary and Norgay are first people climbing to summit and return: 1953. -First female to summit: Tabei 1975 -First climb without oxygen: Habeler and Messner 1978 -most summits: 21, Ang Rita Sherpa. -most important legacy of the Superstack is that it ushered in an ear of ecological awareness, recovery, and restoration in Ontario, and of pride in the natural environment in Sudbury area. The atmosphere and Weather - atmosphere provide O2, absorbs hazardous solar radiation, burns up incoming meteors, transports and recycles water and nutrients and moderates climate. - human activities alter some atmospheric gases, such as carbon dioxide, methane (CH4), and ozone(O3) -Composition of atmosphere: 78.08% Nitrogen, 20.95% Oxygen, other permanent gases and variable gases. The atmosphere is layered -There are four layer. -Bottommost layer: Troposphere 无无无. Provides us with the air we need to live. The movement of air within the troposphere is also largely responsible for the planet's weather. It is thin (average 11 km high). Contains three-quarters of the atmosphere's mass 无无because air is denser 无无 near Earth's surface. Troposphere air temperature declines 6'C for each kilo in altitude. At the top of the troposphere, the boundary called the tropopause(-52'C). all land on earth within troposphere. -temperature gets colder the higher you go. lots of the mixing of the air. means that airborne pollution can make its way up to the tropopause fairly quickly. -The stratosphere 无无无extends from 11km to 50km above sea level. 1000 times as dry and less dense than troposphere. Ozone concentrates in a portion of the stratosphere from 17km to 30km above sea level, called Ozone layer. - Air is thin, does not move around much. contains ozone which absorbs some radiation, causing the stratosphere to warm. Block UV rays. -human modification of the stratosphere: -Why is ozone layer important: the ozone layer screens out incoming solar radiation in the ultra-violet range (10-400nm). A little UV is good for you, stimulates vitamin D production, but too much UV damages the DNA and proteins contained in living tissues. If all UV radiation reached the Earth's surface, few organisms would survive. >99% of UV radiation fails to penetrate the stratosphere. -Stratospheric processes: when oxygen molecules (O2) encounter UV radiation, they tend to split apart into two O atoms. some free O atoms tend to quickly recombine with other O2 molecules to form ozone. when an ozone molecule encounters UV radiation, it splits into O2 and O. In other words, dynamic interactions between oxygen and UV radiation are continually occurring in the stratosphere. This process consumes most of the UV radiation that enters the stratosphere. Concentrations 潜潜潜 of ozone are highest at equator, where incoming radiation is highest. In Canada: lowest during winter, highest in summer. -CFCs is incented in 20th century, these are non-natural combinations of carbon, fluorine and chlorine(CI). These chemicals had numerous useful applications: air conditioning, refrigeration, plastic foam, cleaning computer parts. -in 1970s it was discovered that when CFCs make their way into the stratosphere, they react with UV radiation, the UV causes the CFC atom to release chlorine, which in turn attacks ozone. -chlorine 潜 ordinarily does not leave the troposphere, CFCs transport it to the stratosphere; because CI lasts for decades in the stratosphere, a single CL atom can break down 100,000 ozone molecules. In 1985, a hole in the ozone layer was observed over the southern hemisphere. -poles have thinner ozone layer. -Ozone depletion is a non-linear phenomenon. Scientists assume that ozone depletion would be a gradual process and occur uniformly across the stratosphere. Recall: 潜潜 潜潜潜潜潜潜潜潜潜潜潜潜潜潜潜潜潜潜 -mesosphere 无无无tends from 50km to 80km above sea level. Lie above stratosphere. Air pressure extremely low. -thermosphere 无无无, top layer, extends upward to 500km. -Energy passing through the atmosphere drives ecological systems. The amount of energy arriving at the earth from solar radiation is balanced by a similar amount of radiation leaving the earth's atmosphere. Called exchange of energy. -incoming solar energy: absorbed by oceans and land; absorbed by clouds and atmosphere; -Atmospheric properties include temperature, pressure, and humidity. (atmospheric pressure, relative humidity) 1. atmospheric pressure: -measures the weight per unit area produced by a column of air. -decrease with altitude. 2. relative humidity: - amount of water vapour a given volume of air holds relative to the maximum amount it could contain for a given temperature. 3. temperature: varies with location and time. -temperature differences affect air circulation. -the temperature of air also varies with location and time because the sun's rays strike some area more directly than others. Temperature also varies because of topography, plant cover, proximity of land to water. (microclimate) -solar energy heats the atmosphere, helps create seasons, and causes air circulate. -about 70% of the solar energy is absorbed by the atmosphere and planetary surface, while the rest is reflected back into space. -sunlight directly overhead, air absorbs less energy due to shorter path through atmosphere -the atmosphere drives weather and climate -Weather specifies atmospheric conditions over short time periods, typically hours or days, and within relatively small geographic areas./ the state of the atmosphere at a particular time and place- temperature, wind, cloudiness, air pressure, etc. shorter time periods , highly variable. -Climate describes the pattern of atmospheric conditions found across large geographic regions over long periods-- seasons, years, or millennia. climate is what we expect; weather is what we get./average weather conditions for a given (large) area over longer periods of time -the seasons occur because Earth is tilted on its axis by 23.5 degrees. Jun solstice, September equinox, December solstice, March equinox. -Air movement: warm air rises; by day, as earth surface warms, air immediately above the surface begins rising. rising air increases the pressure at higher altitudes, leaving a lower pressure area behind. Cooler air rushes in to replace the rising air. The air that has risen eventually cools and falls, creating new pressure differentials. -JET STREAM: the high winds at Everest summit 潜潜潜潜潜潜 are caused by the jet stream. The earth rotates from west to east. At high altitudes, combination of Earth's rotation and pressure cells creates fast-moving currents of air. -air masses interact to produce weather. The boundary between air masses that differ in temperature and moisture is called a front. The boundary along which a mass of warmer moister air replaces a mass of colder drier air is termed a warm front 无无. Vise versa is called cold front 无无. The colder air, being denser, tends to wedge beneath the warmer air. Once a cold front passes through, the sky usually clears, and the temperature and humidity drop. - when a warm front approaches, warmer air rises over cooler air, causing light or moderate precipitation as moisture in the warmer air condenses 无无. When a cold front approaches, colder air pushes beneath warmer air, and warmer air rises, resulting in condensation and heavy precipitation. -air mass differ in atmospheric pressure. High-pressure systems typically bring fair weather. Low-pressure system result clouds and precipitation. -temperature inversion 无无 also called thermal 热热热 inversion. normal condition allows vertical mixing, so无无无无无无but thermal inversion 无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无无 -vertical mixing normally allows air pollution to be diluted 无无 upward, but thermal inversions trap pollutants near the ground. -Large-scale circulation systems produce global climate patterns: Hadley cell (sunlight is most intense)s, Ferrel cells, polar cells, Coriolis effect, trade winds. - natural sources can pollute. Winds sweeping over arid terrain 无无无无 can send huge amounts of dust aloft. although dust storms are natural, the immense 无无无 scale of these events is exacerbated 无无无 by unsustainable faming and grazing practices that strip vegetation from the soil, promote wind erosion and lead to desertification. -volcanic eruptions release large quantities of particulate matter, as well as sulphur dioxide 无无无无and other gases, into troposphere. -burning vegetation also pollutes the atmosphere with soot 无无and gases. -we create various types of outdoor air pollution. -primary pollutants such as soot and carbon monoxide are pollutants emitted into the troposphere in a form that can be directly harmful or that can react to form harmful substance. -secondary pollutants are harmful substances produced when primary pollutants interact or react with constituents of the atmosphere. -CEPA identifies harmful airborne substances -1. criteria air contaminants无无include CACs, SO2, NO2, PM, VOCs or VOX -2.persistent无无organic pollutants -3.heavy metals -4.Toxic air pollutants -government agencies share in dealing with air pollution -monitoring shows that many forms of air pollution have decreased -smog is the most common widespread air quality problem -photochemical smog is produced by a complex series of reactions -air quality is a rural issue too -industrializing nations are suffering increasing air pollution -synthetic chemicals deplete stratospheric ozone -there are still many questions to be resolved about ozone depletion -the Montreal Protocol addressed ozone depletion. -1985: international convention was created to address the causes of ozone depletion (Vienna Convention) -1987 follow-up: Montreal Protocol. signatories agreed to scale back CFC production by 50% by 2000. First amendment 无无无: developed nations to phase out all CFCs by 2000, developing countries by 2010. Second amendment: developed nations to phase out CFCs by 1996. -Montreal Protocol causes steady, dramatic decline on CFC production worldwide. It worked. while ozone holes continue to appear at the poles, further damage seems to have been halted 无 无. We are starting to see first signs of reversal of ozone depletion. full recovery not expected before 2050. -it is worked because: 1, the speed of ozone depletion and the potential human health consequences were frightening. 2, developed nations took the lead with aggressive reduction targets. 3, alternatives to CFCs were quickly developed. 4, CFC substitutes are cheap and widely available. - Atlantic ocean circulation -acidic deposition 潜潜潜 (acidic precipitation such as acid rain.)is another trans- boundary pollution problem. -acid deposition has not been reduced as much as scientists had hoped -indoor air pollution in the developing world arises from fuel wood burning -tobacco smoke and radon are the most dangerous indoor pollutants in the developed world -many VOCs (volatile organic compounds 潜潜潜潜潜潜潜)pollute indoor air -living organisms can pollute indoor spaces: dust mites -we can reduce indoor air pollution 潜 using low toxicity materials, monitoring air quality, keeping rooms clean and providing adequate ventilation. Definition: -atmosphere: the thin layer of gases surrounding planet Earth. Compare biosphere, hydrosphere, lithosphere. -Troposphere 潜潜潜: The bottommost layer of the atmosphere, it extends to 11 km above sea level. -ozone layer: contains most of the ozone. -microclimate: Variations in weather and climate that occur on an extremely local scale, such as from one side of a hill to the other. -weather: the local physical properties of the troposphere, such as temperature. pressure. humidity. cloudiness, and wind, over relatively short time periods. -climate: The pattern of atmospheric conditions found across large geographic regions over long periods of time. -front: the boundary between air masses that differ in temperature and moisture and therefore density 潜潜. -high pressure system: an air mass with elevated 潜潜潜 atmospheric pressure, containing air that descends, typically bringing fair weather. -low pressure system: an air mass in which the air moves toward the low atmospheric pressure at the centre of the system and spirals upward, typically bringing clouds and precipitation. -thermal inversion: a departure from the normal temperature distribution in the atmosphere, in which a pocket of relatively cold air occurs near the ground, with warmer air above it. The cold air, denser than the air above it, traps pollutants near the ground and causes a buildup of smog. -Hadley cells: one of a pair of cells of convective 潜潜潜 circulation between the equator 潜潜and 30 degrees north and south latitude that influence global climate patterns. -Ferrel cells: one of a pair of cells of convective circulation between 30 and 60 degree north and south latitude that influences global climate patterns -polar cells: one of a pair of cells of convective circulation between the poles and 60 degree north and south latitude. -Coriolis effect -trade winds: prevailing winds between the equator and 30 degrees latitude that blow from east to west -air pollution: The act of contaminating the air , or the condition of being contaminated by air pollutants. -jet stream: Chapter 15. Global climate change -atmospheric systems and oceanic processes are linked with one another, changes in one affect the other. - what is climate change?: describes trends and variations in earth's climate, involving such aspects as temperature, precipitation and storm frequency and intensity. -The sun and atmosphere keep Earth warm -Greenhouse gases warm the lower atmosphere -the greenhouse effect is a naturally-occurring process that moderates the earth's surface temperature. creates a range of surface temperatures suitable to living creatures. The problem is we are adding more greenhouse gas. -Greenhouse gases: O2, CO2, N2O CH4, CFCs. allow short-wave radiation to pass through unhindered. absorbs re-radiate longer wave radiation. Are known in climate science as forcing agents(water vapour潜潜, Carbon dioxide, methane CH4, Nitrous oxide N2O, CFCs.). - -greenhouse gases: a gas that absorbs infrared radiation released by earth's surface and then warms the surface and troposphere by emitting energy, thus giving rise to the greenhouse effect. -greenhouse effect: the warming of earth's surface and atmosphere, especially troposphere, caused by the energy emitted by greenhouse gases. -carbon dioxide is the anthropogenic 潜 潜 greenhouse gas of primary concern -we are increasing the levels of greenhouse gases in the atmosphere, thus increasing the greenhouse effect. the main natural sources of carbon dioxide moving into the atmosphere is the decay of organic material; volcanoes also emit a significant amount of CO2. -climate is inherentlvariable. climate is always changing. -Why concern about carbon dioxide: 1, it has long been known to have a forcing effect on climate. 2, atmospheric concentrations have increased rapidly in past 200 years, with no known source except human activity. -extremes of past millennium: Medieval warm period; little ice age;. -WE HAVE ALREADY IDENTIFIED SOME KEY FORCES/PROCESSES THAT AFFECT CLIMATE: incoming solar radiation/ circulation of air/ circulation ofocean water/ long-term oscillations(e.g. ENSO)/ presence of greenhouse gases (forcing agents). here are some more: position of the earth in its orbit 无 无 causes seasonal changes in climate/ milankovich cycles(orbital variations cause the distance between earth and sun to vary over time, thereby influencing amount of solar radiation received)/ sunspots: the amount of radiation the earth receives from the sun is generally consistent, but occasionally there are sunspots(flares 无 无 of solar activity)/albedo(the reflectivity of a surface)无 无无无无: is the degree of reflectivity of a surface, like snow, tops ofclouds they tend to reflect solar radiation; dark surface absorbs it. lots of snow: high albedo./volcanic activity: produce large amounts of smoke, particulate that temporarily block incoming radiation, also produces greenhouse gases. -global average sea level is rising; northern hemisphere snow cover is thinner; global average temperature is higher. only greenhouse gas concentrations changed. -human activity has released carbon from sequestration in long-term reservoirs -other greenhouse gases contribute to warming -there are many feedback cycles in the climate system -radioactive forcing expresses change in energy input over time -the atmosphere is not the only factor that influences climate -in equatorial regions, the oceans receive more heat from the sun and atmosphere than they emit. near the poles, ocean water emits more than it receives. -one ocean-atmosphere interaction that influences climate is the EL Nino-- Southern Oscillation 无 无(ENSO), a systematic shift in atmospheric pressure, sea surface temperature, and ocean circulation in the tropical Pacific Ocean. -El Nino conditions are triggered when air pressure increases in the western Pacific and decreases in the eastern Pacific, causing the equatorial winds to weaken. Know from ice cores to have occurred for thousands of years. Affects air circulation and precipitation patterns around the world when it occurs. -La Nina events are the opposite; under these conditions, cold surface waters extend far westward in the equatorial Pacific. La Nina is a strong reversal of an EL Niño event, with equatorial temperatures in Pacific Ocean being cooler than average. -Both El Nino and La Nina have dramatic influences on global weather patterns. ENSO cycles are periodic but irregular, occurring every two to eight years. Scientists are also investigating whether globally warming air and sea temperatures may be increasing the frequency and strength of these cycles. -ENSO years: weak trade winds, difference of water level. ENSO has considerable effects on global climate. 1997 to 1998, ENSO causes heavy rains in east Africa, droughts and forest in tropical Indonesia. - -Milankovitch cycles: -solar output: -ocean currents and climate also interact through the thermohaline circulation: a worldwide current system in which warmer, fresher water moves along the surface and colder, saltier water moves deep beneath the surface. In the Atlantic Ocean, warm surface water flows northward from the equator in the Gulf Stream, carrying heat to high latitudes and keeping Europe warmer than it would otherwise be. As the surface water of this conveyor belt system releases heat energy and cools, it becomes denser and sinks. -water temperature: warmer in West, colder in east. -proxy indicators (northern hemisphere temperature )tell us about the past -stable isotope geochemistry is a powerful tool for the study of paleoclimate -direct atmospheric sampling tells us about the present -models help us understand climate: GCMs -current and future trends and impacts: the IPCC summarizes evidence of climate change and predicts future impacts -changes in precipitation will vary by region -melting ice and snow have far-reaching effects -the arctic is changing dramatically: warming temperatures are already reducing snow cover, affecting permafrost 无 无 无 无stability at high latitude and melting the immense ice sheets of the Arctic. one reason warming is accelerating in the arctic is that as snow and ice melt, darker, less-reflective surfaces are exposed and earth's albedo or capacity to reflect light decreases. -rising sea levels will affect millions of people in coastal zones and on islands: worldwide, densely populated regions on low-lying revier deltas will be mostly affected. -climate change affects organisms and ecosystems: birds migrating earlier. -climate change exerts societal impacts--and vice versa: agriculture, forestry, health(natural disaster), economics. -are we responsible for climate change? Scientists agree that this increase in greenhouse gases results primarily from our combustion of fossil fuels for energy and transportation and secondarily from land use changes, including deforestation and agriculture. -Responding to climate change: shall we pursue mitigation, adaptation, or intervention? -we can look more closely at our lifestyle -transportation is a significant source of greenhouse gases: automotive technology, driving less and using public transportation. -we can reduce emissions in other ways as well -we will need to follow multiple strategies to reduce emissions -we began tackling climate change by international treaty -market mechanisms are being used to address climate change -carbon offsets are in vogue -you can reduce your own carbon footprint Guest: There are 3 main reasons behind Arctic amplification: Long-range: 1: Radiative Forcing: Atmospheric GHGs trapping heat - Pollution in the south can get to the Arctic “long-lived green house gases” Local feedbacks 2: Decreased Arctic ice - melting sea ice is absorbance of heat 3. Decreased albedo How these addressed: scientific efforts mixed with traditional knowledge. community based projects sharing knowledge to create a monitoring program. Youth Conference on Climate Change: Teaching the next generation of leaders. Science camps ever summer to educate youth on ecological sciences and traditional knowledge. Green houses and gardening have also been on the rise! Chapter 7 and 8 -soil is a complex, dynamic mixture. - Soil availability • Some places have lots of good soil, others may have none at all -Soil is fragile • In takes decades or more to form a few inches of soil • Soil can be removed from poorly managed land in a single season Soil particle size • Clay: microscopic无无无 • Silt: 0.002-0.02 mm • Sand: 0.02-2 mm • Soil classification is based on the proportion of each type Important characteristics - Larger soil particles 无无 have larger spaces between them (are more porous) Important. soils with large particles tend to have larger spaces that are highly interconnected allowing water to pass through too quickly. -Smaller particles have a greater proportion of surface area relative to volume -Water and nutrients tend to cling 无无 to surfaces - Soil quality • For agricultural production, a soil containing a mixture of particle sizes is desirable • Ensures availability of nutrients, ability to hold water and is workable • Compacted soil lacks pore space for movement of water, air What makes soil fertile? • Availability of nutrients, minerals (P, also K, Ca) • Ability to hold water (but not too much!) • Aeration • pH near neutral (i.e. neither especially acid nor alkaline) • Minimal amount of salt Organisms in the soil • Break down organic material on surface, creating humus • Create concentrated particles containing mixtures of humus/minerals • Improve soil structure (make it nice & loose) • Some bacteria draw nutrients to plant roots • Not all are helpful (e.g. nematodes) Soil -soil formation is slow and complex -a soil profile consists of layers know as horizons: O Horizon: surface deposits of leaves, branches, mosses, animal waste. Humus: a dark, spongy, crumbly material in the soil, composed of complex organic compounds, resulting from the partial decomposition of organic matter. (plant litter, other decomposing organic material) A Horizon: Topsoil (mix of humus and leached mineral soil) B Horizon: are called Subsoil (accumulation of leached minerals e.g. iron & aluminum oxides) C Horizon: consist Weathered parent material (partly broken down) a transition zone R Horizon: Parent material (rock) -soils vary in color, texture, structure, and pH -soils support plant growth through ion exchange -soil is a crucial part of the nitrogen cycle. (nitrogen fixation, nitrification, denitrification) -soil is an important terrestrial reservoir for carbon -soil degradation is a global concern: resulted from erosion caused by roughly equal parts forest removal(30%), poorly managed cropland agriculture(28%), and over-grazing (34%) of livestock with a much smaller contribution from industrial contamination. -regional differences affect soil productivity: the characteristics of soil and soil profiles vary from place to place. difference between soils of tropical rainforests and those of temperate grasslands. -erosion can degrade ecosystems and agriculture -Soil Degradation • Erosion(is the removal of weathered material from one place and its transport to another by the action of wind, water or glacial ice). We lose 5-7 million hectares of productive cropland annually. Erosion: Human Factors • Removal of vegetative cover (e.g. deforestation) • Over-cultivation • Irrigation • Overgrazing • Desertification -Cause: Too much plowing (over-cultivation 无 无 ). -the Dust Bowl was a monumental event in North America. price of wheat is lower than seeds/ Nutrient exhaustion from monoculture/ Overgrazing/ -soil erodes by several mechanisms -soil erosion is widespread Erosion: Associated problems •Loss of soil fertility – Solution=fertilizers • Associated problems: utrophication 无无无无 • Sedimentation • Desertification -desertification reduces productivity of arid lands Desertification • Water-holding capacity is diminished: Related to erosion processes • ‘Drylands’ cover 1/3 of Earth’s land area – Home to 2 billion people – Defined by rain-fall not temperature • 19% earth's land surface threatened Desertification in W. China: • Immediate Causes: – overgrazing + overplowing 无无无无 of marginal lands – Inefficient water use • Distal 无无无 Causes: – removed controls on herd sizes (’78) – Population pressure • Results: – 1,000 sq miles/year lost to desert – Diminished productivity – Health impacts – Dust storms -the Soil Conservation Council emerged from the experience of drought -erosion-control practices protect and restore plant cover (crop rotation/intercropping and agroforestry/ contour farming and terracing/ shelterbelts/ reduced tillage) -irrigation can causes long term soil problems -other chemicals also contribute to soil contamination潜潜 -grazing practices can contribute to soil degradation -Food security: Food security exists when all people, at all times, have physical and economic access to sufficient safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life. (1996 World Food Summit). Making a food supply sustainable depends on maintaining healthy soil, water and biodiversity. • 4 dimensions of food security: – Availability – Access – Utilization – Stability • Food production not the real (current) problem: we are producing more food per person. THREATS TO FOOD SECURITY: • Soil degradation* • Changing diets: The lower on the food chain from which we take our food sources, the more people the Earth can support. Meat production is -consumption of animal products is growing increasing from 1960 to 2000. -high consumption has led to feedlot agriculture • Food to energy fuel • Climate change • Technology (e.g. GMOs): new problems * The direct manipulation of an organism’s genetic material in the lab by adding, deleting or changing segments of its DNA GOALS: • Disease resistance • Drought tolerance • Improved nutritional value • Incorporate human vaccines • Longer lasting products • Biofuel production • Food production Genetic modification: improving or threating food security? – Environment: • Pest resistance to engineered toxins • Broad spectrum impact on non-target species • Genetic drift - “Super weeds” • High disease vulnerability – Health • Proteins – possible allergic responses • Antibiotic resistance to human pathogens • New toxic substances • Uncertainty of risks to humans • Access to new technologies – Profit driven – Affordability in developing countries – Multi-national control (e.g. Monsanto) – Terminator technology: seed sterility • Consumer acceptance • Cartagena Protocol on Biosafety (2003): • Importing countries must have necessary info to make informed decisions • Conflict, Politics & Policies War • Corruption • Distribution • Neglect of rural populations • Control of populations • Manipulation of markets (keep prices low) TRADE POLICIES AND SUBSIDIES • Benefits of subsidies: stability for national agricultural sector • Problems with subsidies: – Drive down international prices artificially – Mis- allocation of resources – Mostly large farms that benefit http THREATS TO FOOD SECURITY • Erosion and desertification = significant threats to food production globally • Growing demand for food as populations grow • Continued effort to increase production/yield • But…food security is about more than just availability: – Recall: the 4 dimensions of food security: – Availability – Access – Utilization – Stability -agriculture first appeared around 10,000 years ago -industrialized agriculture is more recent -we are producing more food per person -we face undernourishment, overnutrition, and malnutrition -the Green Revolution led to dramatic increases in agricultural productivity -Keeping UP with population growth: The Green Revolution • 1940s – 1960s and beyond • Technology transfer to developing nations • Introduction of high yield hybrid varieties (HYVs) – wheat, rice, corn • Still going on: • Development of new crops; pest resistance; expansion into other regions -before green revolution the best way to increase agricultural productivity was to plant more land with crops or to increase the size of a herd which is called extensification. -the Green Revolution has had both positive and negative impacts (fertilizer impacts/irrigation impacts: use of fresh water/monoculture impacts: biodiversity) -thousands of chemical pesticides have been developed -pests evolve resistance to pesticides -biological control pits one organism against another -biocontrol agents themselves may become pests -IPM combines biocontrol and chemical methods -we depend on insects to pollinate 潜潜潜crops -conservation of pollinators is vital -genetic modification of organisms depends on recombinant DNA -genetic engineering is like, and unlike, traditional breeding. -biotechnology is transforming the products around us(3/4 of the world's soybean plants are transgenic.) -what are the impacts of GM crops? -debate over GM foods involves more than science -crop diversity provides insurance against failure -seed banks are living museums for seeds -our food choices are also energy choices -we also raise fish on farms -aquaculture has benefits and drawbacks(reducing fishing pressure and declining wild stocks, provides employment for fishers./incidence of disease that reduces food security. ) Moving forward • Sustainable agriculture (p. 236-240) • Funding for research • Better regulation of biotechnology • Limit diversion of food to fuel • Modify consumer behaviour • Limit density of livestock • Crop rotation • Contour farming • Terracing • Intercropping • Shelterbelts • No till or low-till farming -as population and consumption increase, soils are being degraded -organic agriculture is on the increase Consumer choices: e.g. Organic foods • Grown without bug killer, fertilizer, hormones, antibiotics or biotechnology • Reac
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