EESA01 Lecture and Chapter Notes for Whole Course.docx

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University of Toronto Scarborough
Environmental Science
Carl Mitchell

EESA01 Lecture 1 – Chapter 1 (both text books) 10/26/2012 1:56:00 PM An Introduction to Environmental Science Our Environment is more than just our surroundings  Environment : sum total of our surroundings  all biotic and abiotic components with which we interact Environmental Science  study of how our natural world works, how our environment affects us and how we affect the environment Natural resources are vital to our survival  Natural resources: various substances and energy sources we need to survive  Renewable: natural resources which are replenishable over time  sunlight, wind, wave energy  Some resources such as agricultural crops, fresh water, forest products and soils are renewable if used properly  if over-used then they become nonrenewable resources  Resource management: planning on how to use a resource in such a way that we are still protecting and preserving it  Stock is the harvestable portion of the resource  if resources are being withdrawn from the stock at higher rates than it is being replenished, then the stock will eventually be depleted  Non-renewable : in finite supply and are depleatable  fossil fuels, mineral deposits, natural gas etc.  They are deplated because they are formed much more slowly than we use them  100 million years for natural geological processes to form an ore deposit or a petroleum deposit Tragedy of Commons and Carrying Capacity   Earth’s carrying capacity is between 10 million and 33 billion  Carrying capacity: the ability of a system to support life  number of individuals of a certain species that can be sustained by biological productivity of a certain area of land  When carrying capacity of the system is exceeded either population will decline or collapse or the system itself will be altered, damaged or depleted  Once carrying capacity is reached, the amount of births = amount of death that occur per year  Tragedy of the commons concept  proposed by Garret Hardin in 1968  Unregulated exploitation leads to resource depletion  Resource users are tempted to increase use (people use the resources as much and as quickly as they can) until the resource is gone  Is this still the basis for ongoing environmental issues?  Can we do anything about it?  In some countries like China, private land ownerships has been introduced  people tend to take more care of their land when it is theirs, so they will make better decisions when it comes to using its resources  In other cases people who share a part of land get together to enforce its responsible use  In other cases government regulation may be required  Each approach has its own strengths and weaknesses Ecological Footprint  Ecological footpring is a tool that can be used to express the environmental impact of an individual or the population  Calculated in terms of land and water needed to provide the raw materials that the person or population consumes and to absorb or recycle the wastes produced  Essentially the inverse of carrying capacity  Some nations have smaller ecological footprints than other  Canada’s ecological footprint is of 7.6 ha which is lower than the US (9.6ha) but a lot higher than India (0.8ha)  Biocapacity: capacity of a system to be biologically productive and to absorb waste (especially CO2)  Our species is not using 39% more resources than are available  using resources 39% faster than they are replenished  Right now we would need 1.4 worlds to sustain all people  we are already over  If everyone lived like Canadians, we would need 4 planets to survive Rapa Nui (Easter Island)  Discovered by Europeans in 1722 – had population of less than 2000 that basically lived in caves  The presence of intricate and huge statues suggested that a sophisticated civillzation once lived there  The island was once lushly forested supporting 6000-30000 individuals  Civilaztion over-used the resources of the islands and cut down all the trees  This caused starvation and conflict which eventually destroyed the once flourishing population  21 species of plants (including trees) which were once common on the island are now extinct  with the trees gone, soil eroded away which degraded agricultural lands  less crops = less food = starvation for the people  and faster runoff of water meant less available freshwater for drinking  6 species of land birds and 25 species of seabirds were eaten by the people  today no native land birds are left and only 1 species of sea birds  with the trees gone they could not build canoes to fish, so they could not get food that way and feed on seafood  without any resources left, the islandars fell to war with each other and killed each other for what was left of any resources  population eventually died off 2 Environmental Science is an interdisciplinary pursuit  Environmental science is an interdisciplinary field  employs concepts and techniques from numerous disciplines and brings research results from these disciplines together into a broad synthesis The Base Cause of Environmental Degradation  His opinion: the environmental issues that we face today are due to a combination of world population growth and consumption (energy) far above what can easily be replaced or supported and a general ignorance to recognize this for what it’s true value is  i.e there are too many of us, and we use too much but we are ignorant of the fact Environmental Scientist vs. Environmentalist  a scientist is not necessarily and environmentalist (who has a biased view about the environment) AND an environmentalist does not need to be an environmental scientist  Environmentalism: social movement dedicated to protecting the natural world from undesirable changes brought about by human choices The Nature of Science  Science is the systematic process for learning about the world and testing our understanding of it How does Science work?  Science is curiosity focused towards a question that scientific method can help to inform  The scientific method is a set of rules which prescribe how to derive knowledge of a particular kind – certified, validatable knowledge  Using the scientific method one cannot show that a theory is right, only that it is not wrong  Any notion of the world (theory) is only not wrong until scrutiny reveals it to be incomplete  any theory is good until the first piece of info is gained which the theory cannot accommodate (example: evolution, sun at the center of the Earth etc.)  Our science based understanding of the universe is always changing because of doubt, scrutiny and the acquisition of new information  doubt and questioning lead to better understanding  There is no absolute truth in science, but we do have laws  a natural phenomenon that has been proven to occur invariably whenever certain conditions are met Scientific Method Observations  question  hypothesis predictions  test  results  If results reject the hypothesis (hypothesis is wrong), then you must go back and make new hypothesis and re-do everything again  An experiment involves manipulating variables  scientist manipulates the independent variable while keeping the dependant variable constant 3 There are multiple ways to test a hypothesis  Example: farmer outside of Newmarket notices that his pond has an unusually amount of high algae in it  so his cattle will not drink from it o Hypothesis: run off which is high in N and P (from the farmer’s fertilizer) seeped down to the pond and caused the algae population to increase o Experiment: test the levels of N and P  if high, decrease the levels of N and P and algae population will decrease  cattle will drink from pond again  Manipulative experiment: scientist actively chooses and manipulates the independent variable  Natural experiments: experiment is conducted naturally (scientist does not manipulate anything) and he/she then analyzes the data  In many disciplines both kinds of experimentation are used and compared to one another Cornucopians vs. Cassandras  Cornucopia: horn of plenty  human ingenuity will see us through our environmental problems via new technologies and such  Cassandra: mythical princess of Troy who prophesized about dire future scenarios  all is lost because of our impact on the environment Sustainable Development  Development (economic advancement through the use of natural resources) that meets the needs of the present without sacrificing the ability of the future generations to meet their own needs  Brundtland Comission  Solutions to environmental problems must be global and sustainable Social Impacts Must be Considered  When the rich get richer and the poor get poorer, both groups suffer  20 wealthiest nations currently have 40x the income of the 20 poorest nations  this gap is 2x as large as it was 40 years ago  As a consequence of polarization of wealth and opportunity, the environment is degraded, thereby impoverishing everyone forever  Through limiting our current environmental impact, while still promoting economic well-being and social equity, we have a chance at an environmental future  It is up to the people to decide how this will be done  what are you going to do to lower the impact on the environment? Examples of Practical Solutions  Scrubbers on smokestacks  Recycling  Renewable energy like solar and wind power  Best management practices in natural resource extraction and agriculture 4  All of these practical solutions though are very costly $$ 5 EESA01 Lecture 2 – Chapter 6 9/10/2013 4:07:00 PM Population and Environmental Consequences Population – A Root cause of Environmental Degradation  Much of the environmental degradation in the world is due to population growth and wide misuse and overuse of resources by too many people o i.e. there are too many of us, using too much improperly Resources consumption exerts social and environmental impacts  Population growth affects resource use and availability and is the basis of many environmental problems  In 1974 Paul Ehrlich and John Holdren came up with the IPAT(S) model  I = P x A x T (x S)  I = impact on the environment, P = population, A = affluence and T= technology, S = sensitivity  This model shows that impact is a function of not just population but also affluence (level of consumption) and technology  boils down to pollution or resource consumption  Individuals need space and resources  as the amount of money we make increases, we use more resources  technology allows us to better exploit resources, and so we use even more  The impact on the environment also depends on the sensitivity of the area to human pressure (S)  arid lands of western China are more sensitive to human disturbance than the moist regions of southwestern China The First Humans  Oldest known hominid (human like fossil): o Ethiopia 4.1 million years ago  Lucy (ausrtalopithecus afarensis) o Chad 7 million years ago  Toumai (sahelanthropus tchadensis) Doubling Time  The number of years it takes, given a specific rate of increase for a number (such as population) to double ln(2)´100 70 t = = D  growthrate(%) growthrate(%)  in 1979 China’s growth rate was of 2.8% and the population at the time was of 1.0 billion  the population of china now is 1.3 billion which is less than expected because these calculations assume that the growth rate will not change over the years (which it does)    Canada’s growth rate is 0.9% (natural and immigration together)  Canada’s only reason for positive growth is immigration  The population of Canada is about 33.5 million Global Population Growth   it took most of human history (until about 1800) for the global population to reach 1 billion people  now, we have doubled our population since 1966 (a bit less than 50 years)  not population of a bit over 7 billion people  even though population growth rates have declined to about 1.2%, we are still groing and even a small rate with such a large population number is severely compounded over time  like a bank account, interest is small but when you have A LOT of money, you make a lot every month  Malthus warned that population growth would have disastrous effects on the environment and human welfare Carrying Capacity and Uncertainty  On Earth, we are unsure of which of the trends will happen once we hit our own carrying capacity  Human population growth has shaped our resource use   Paleolithic period (Stone age): humans gained control of fire and began to shape and use stones as tools with which to modify their environment, also had omnivorous diet and developed speech and communication  little evidence of population at the time 7  Neolithic period (Agricultural Revolution- 10-12000 years ago): transition from nomadic, hunter-gatherer lifestyle to a settled, agricultural life style o Deglaciation occurred (glaciars started to recede) o This lifestyle meant:  reduction of area needed per person,  500x higher population density,  excess of food production over minimum,  whole population need not be in food production or acquisition  people could do other things than just hunt and gather food  settlements were established  social structures  priests, accountants, salesmen  “Fertile Crescent”  area in the middle east destroyed by overirrigation and salinization caused by the collapse of the society because food demands were no longer met  overall, needs were easier to meet, so it resulted in population increase  Industrial revolution (mid 1700s in Great Britain): shift to an urban society powered by fossil fuels  lives improved significantly but this period also marked the beginning of pollution and other social and environmental issues that we had not dealt with before o Air quality, water quality and urban landscape declined, workplace health and safety declined as well o Improved sanitation and medicine o Major advances in agriculture (powered machinery) = increased food production o Greater supply of energy, resources, labour o Accumulation of wealth and market for manufactured goods  Today we are in the midst of the 4 thtransition called the Medical-Technological Revolution o advances in medicine and sanitation o explosion of communication technologies and the shift to modern agricultural practices (use of fertilizers etc.) known as the Green Revolution  have allowed people to live longer and healthier lives , but we are also facing new environmental challenges as a result o gap between the rich and the poor has widened  Each of these periods improved the lives of the humans, allowing their populations to increase dramatically Demography  Demography is the study of human population  Takes into consideration: population size, density and distribution, age structure, sex rations, births, deaths, immigration and emigration rates  These and other factors (IPATS) shape a population’s environmental impact Population Growth and Density 8   population density = the number of people per unit of land area  highest population density is in temperate, subtropical and tropical climates  high population growth rates in these areas  low population density where far away from water or where climate is extreme  this means certain areas of the world bear more environmental impact than others  but the reason why certain areas have low population density is due to their sensitivity of human impact  cannot support many people, ex: deserts Age Structure Affects Future Population Dynamics   population pyramids: visual tools used to illustrate age structure  the width of the bars is related to the size of the population  if there are a lot of people of reproductive age, then the population will increase rapidly  if there are a lot of elderly people, then there will be a lot of deaths which may overcome the number of people born and result in a decreasing population  Canada looks like the decreasing pyramid  in this example: Madagascar’s population is growing faster than Canada’s because the have the increasing quickly pattern for population growth whereas we have the decreasing population growth (because the top age group is the greatest which means there are a lot of old people)  older populations will present financial challenges are care is necessary by more people and there are less people working to assist them Sex Ratios  What sex of babies are born more, girls or boys?  There is a slight natural preponderance toward males being born  106 males for every 100 females  This is likely an evolutionary response as males are more likely to die by accident before reaching sexual maturity  LOL boys are stupid 9  In the United Arab Emirates and Qatar, the ratio is closer to 200 males for 100 females  such rations are bound to lower population growth rates  Culture gender preferences combined with government one-child policy left to selective abortion of female fetuses (in China the ratio is 120 males to 100 females)  resulted in a lot of single Chinese men  so teenage girls were kidnapped and sold as brides The Demographic Transition   pre-industrial stage  both death rates and birth rates are high  transition stage  pre-industrialization initiates 2nd stage of transition as death rates decline due to increased food availability and better medical care  industrial stage  industrialization increases job opportunities, especially for women and children become less valuable  birth rates decrease as people choose to not have kids and use birth control  post-industrial stage  birth rates and death rates are low  population size stabilizes or slightly declines  mortality decreases before the perceived need for children does  i.e death rate decreases before birth rate does  population growth is seen as a temporary phenomenon that occurs as societies move from one stage to another Is the demographic transition universal?  It has occurred in Europe, U.S, Canada. Japan and other nations over the past 200-300 years  The transition could fail in cultures that place greater value on childbirth and grant women fewer freedoms (no birth control, no choice of abortions etc.)  There would also not be enough resources for the whole world to live like the people in first world countries do Factors Affecting Population Growth (1) Education and status of women as well as family planning availability/knowledge & population policies 10  Total fertility rate refers to the number of children born per female in her lifetime  Fertility rate decreases as education of women increases  Neighboouring nations (2 nd figures) shows one country introduces education about birth control, more rights to woman, and more access to health care  the country’s TFR decreases, whereas their neighbouring country has also decreased but not as much  Replacement fertility rate is 2.1  is the total fertility rate value which keeps the size of a population stable (of the whole world) o Without immigration (for one country), if the replacement fertility rate drops below 2.1, then the population will shrink (2) Poverty   total fertility rate is higher in poorer countries  82% of the world’s population live in developing countries  99% of the next 1 billion people will be born in these poorer, less developed regions  much of the world’s poor live in sensitive areas  where S is high  like Sub-Saharan, Africa agriculture  these poorer nations tend to be stuck in the demographic transition, thus population growth rates are large (3) Disease, especially HIV/AIDS  huge problem in Africa  one cause for not necessarily following the Demographic transition  mortality is rising instead of dropping because of this disease  1 in 5 people aged 15-49 in southern Africa have HIV/AIDS 11  HIV/AIDS is now also a growing problem in eastern Europe and central Asia Some Glimmers of Hope  Although the global population continue to grow, growth rates are declining almost everywhere  Women’s rights and access to education are being expanded in many places which will have great benefits to reduce population growth and impacts on the environment  Millenium Development Goals  in 2000 world leaders came together to set out a framework of basic goals for humanity over the next 15 years (by 2015)  goal is sustainable development  Demographic fatigue: o when a developing country has lowering mortality rates and increasing birth rates it goes through a phase of high population growth which is part of transition towards being a developed country o but then the government will lack financial resources to stabilize its population's growth and becomes unable to deal effectively with threats from natural disasters  so the developing country falls back to stage 1 of the demographic transition where there are high mortality rates and high birth rates 12 Lecture 3 – Chapter 3 9/10/2013 4:07:00 PM Earth Systems, Ecosystem Ecology, and Global Biogeochemical Cycles Systems  System is a network of relationships among parts, element or components that interact with and influence one another through the exchange of energy, matter or information  System receives energy, matter or information  inputs  Systems process these inputs and produces outputs  There are open systems and closed systems  Open systems receive inputs of both energy and matter and produce outputs of both  Closed systems receive inputs and produce outputs of enerby, but not matter  Feedback Loops  the circular process where the output can server as input  feedback loops  Negative feedback loop: output from system becomes input to system, moving that system in opposite direction  input and output cancel out each other’s effects therefore stabilizing the system o Because negative feedback loops enhance stability, they are therefore more abundant in nature  Positive feedback loop: output exacerbates the system response by moving it further towards one extreme  no stabilization o Common in natural systems that have been altered by human impact  Example of negative feedback loop for temperature regulation: increasing temperatures  more cloud cover  less solar radiation input  lower temperatures  Example of positive feedback: in cool climate sunlight reflects off white surfaces  as climate warms, sunlight is absorbed where dark surfaces are exposed (i.e. where snow melts)  light absorption speeds warming, exposing more dark surfaces  this is a devastating effect for sea ice and glaciers that cover land (caused by global warming, ice is melting) Equilibrium  Steady state EQ  system fluctuates around a stable average and maintains same operation level o Homeostasis: the tendency of a system to maintain constant or stable internal conditions  Resistance: strength of system to remain constant  Resilience: how readily the system will return to its original state once it has been disturbed  Dynamic EQ  system fluctuates around a stable average, but exhibits a trend overall  it is not static and unchanging, it is ever-adjusting  Emergent Properties  Emergent properties are characteristics of a system not evident from its components alone or individually  the whole is more than the sum of its parts  In environmental science, the system that one might study has everything with the question being asked  Example: a tree is made up of leaves, trunk, water, chloroplasts etc but from these characteristics alone, you would not be able to see/ predict that the tree itself (as a whole) provides animal habitat, it is an element of the forest ecosystem and a CO2 sink (uses up carbon dioxide) Major Earth Systems  Ecosystems  Hydrologic cycle (next class)  Gloabal energy balance (next class)  Biogeochemical cycles: carbon cycle, nitrogen cycle, phosphorus cycle, sulphur cycle, mercury cycle etc.  Systems have boundaries, but can overlap if they are open systems  anthropospehere, cryosphere, hydrosphere, biosphere, lithosphere, atmosphere o Geosphere  rock and sediment (land) o Atmosphere  air o Hydrosphere  water o Cryosphere  subsystem that consists of the perennial froezen parts of the hydrosphere  ice o Biosphere  life o Anthroposphere  humans (parts of the environment that are built or modified by humans) Ecosystems: A broader step up from Community Ecology 14  All organisms and nonliving entities that occur and interact in a particular area at the same time = ecosystem  Includes abiotic and biotic components  Energy flows and matter cycles are among these componenets  Generally described as the smallest ecologically “self-sufficient” space  Ecosystem ecology = study of energy and nutrient flows among living and non living components of systems Ecosystem Structure  Energy is recycled through ecosystems, while matter is recycled within ecosystems  Energy entering the system is processed and transformed and exits the ecosystem  Matter is recycled within ecosystem, resulting in outputs such as heat, water flow and waste products  Conversion of Energy to Biomass in Ecosystems  Biomass: organic material that makes up living organisms  Autotroph: an organism that produces complex organic compounds from sunlight and inorganic molecules (i.e. plants and some bacteria)  Gross Primary Production (GPP): overall conversion of solar energy into chemical energy by autotrophs  Respiration: metabolism o Photosynthesis occurs in the presence of light and chlorophyll o o respiration involves the use of accumulated carbon to produce needed energy C H O +6O ®6CO +6H O+Energy 6 12 6 2 2 2 o  Net Primary Productivity (NPP): energy remaining after respiration, that goes toward accumulating biomass o Ecosystems whose plants convert solar energy to biomass rapidly are said to have high NPP 15   aquatic ecosystem have the higher NPP  Net Ecosystem Productivity (NEP): NPP minus heterotrophic respiration and herbivory  Secondary production: total biomass hat heterotrophs generate b consuming autotrophs Factors Affecting Net Ecossytem Productivity (NEP)  Nutrients o Nutrients are elements or compounds that organisms consume and require for survival o Macronutrients are nutrients that are required in large amounts (N,C,P) o Nutrients, especially macronutrients like nitrogen and phosphorus, can be limiting factors for productivity  because they limit plant and algal growth o Micronutrients are nutrients which are required in relatively small amounts o N is usually the limiting factor in marine systems, and P in freshwater systems  Oxygen o Aerobic respiration produces 2872kJ per mol of glucose C H6O +612®6CO6+6H O 2 2 2  o some types of anaerobic produce almost as much energy per mol of glucose, but some produce significantly less   210kJ/mol of glu  2715kJ/mol of glu Ecosystem Services 16   areas where ecosystems meet often consist of transitional zones called ecotones, in which elements of each system mix Biogeochemical Cycles  Earth is a closed system  open to energy, but matter “cycles” within it over and over again  nutrient cycles are called biogeochemical cycles  Matter travels through the many spheres of earth continuously  From a biogeochemical cycle standpoint, by matter, we usually are reffering to elements such as C, N, P, S, and Fe  Matter circulates between pools or reservoirs  The volume of material moving among reservoirs per unit time (rate) is called a flux  Fluxes are not necessarily stable  we have greatly affected the C flux  Residence time (T ): average amount of time a molecule or atom stays in a pool R  Sources vs sinks  a source produces matter while a sink uses it up  example: plants are a carbon dioxide sink and an oxygen source  Turnover time: the time it would take for all the atoms of a particular material to be flushed through a particular reservoir  balance between fluxes into and fluxes out of the reservoir o  There are lots of feedbacks in biogeochemical cycling 17 Global Carbon Cycle   producers pull C from surface of water and atmosphere to use in photosynthesis  autotrophs use some of the carbs to fuel their own respiration, so some of the carbon goes back into the ocean or into the atmosphere  primary consumers eat producers and they are eaten by secondary consumers and so on  carbohydrates are broken down in respiration and more carbon is returned to water and atmosphere  same process occurs when decomposers consume waste and dead organic matter  some of the carbon taken in becomes part of tissues  plants are a major reservoir of carbon  as organisms die their remains settle in sediments in ocean basisns or freshwater wetlands  converts soft tissues into fossil fuels due to high pressures over time  shells and skeletons turns into sedimentary rock such as limestone  largest reservoir of carbon in the cycle  carbon trapped in sedimentary rock and fossils re enter the atmosphere due to geologic processes  the ocean is the second largest reservoir in the carbon cycle Importance of Nitrogen  78% of atmosphere  6thmost abundant element on earth  key ingredient in proteins and DNA  essential nutrient for plant growth 18  actually a relatively inert element and is quite scarce in lithosphere, hydrosphere and biosphere Key Processes in the Nitrogen Cycle  Nitrogen fixation o Combination of nitrogen gas with hydrogen to form ammonia (NH ) and the biologically available 3 + and soluble ammonium ion (NH ) 4  2 driving processes: lightning, and nitrogen fixing bacteria  Nitrification o Conversion of ammonium to NO 2-and then NO 3-by specialized bacteria  plants then take up NO 3-  Denitrification - o Conversion of NO ba3k to N gas 2y specialized bacterial communities Global Nitrogen Cycle   reservoirs are in balck and fluxes are in red  numbers are in teragrams (10 12grams per year) Human Alteration of N Cycle  Doubling of nitrogen fixation  due to Haber-Bosch process and increased production of legumes (soybeans)  Increased atmospheric N2O (greenhouse gas) and other NO (produce smog)  due to fossil fuel burning and animal waste decomposition  Depletion of micronutrients (Ca, K) from soils (N fertilizers make them more mobile so they flush out)  Acid rain  Eutrophication  devastating to fisheries (especially coastal marine fisheries) 19 o The process of nutrient over-enrichment  causes blooms of algae  increased production of organic matter  increases population of animals  use to much oxygen  suffocation dead zone - ecosystem degradation o o Gulf of Mexico Dead zone o  Increase plant growth and carbon storage Global Phosphorus Cycle   reservoirs are in black in teragrams and fluxes are in red measured in teragrams per year Importance of Phosphorus  Key component of cell membranes, DNA and ATP  Often limiting nutrient for autotroph growth  Biogeochemical cycle is largely restricted to lithosphere and hydrosphere (NOT atmosphere) 20  Cycle is driven by : solubilization, precipitation, assimilation and decomposition Human Alteration of the P Cycle  Mining of phosphorus bearing rocks for fertilizer production  Wastewater/sewage discharge  Eutrophication via over-fertilization  mainly freshwater eutrophication (because saltwater eutrophication is caused by N)  Use of phosphate detergents Global Mercury Cycle  21 Lecture 4 – Chapter 2, Chapter 14, Chapter 15 9/10/2013 4:07:00 PM CHAPTER 2: Matter, Energy and the Physical Environment The Rock Cycle   igneous rock is formed when rock melts and the resulting magma or lava then cools  sedimentary rock is formed when rock is weathered and eroded and the resulting sediment is compressed and cemented to form new rock  metamorphic rock is formed when rock is subjected to intense heat and pressure underground A Cut Through the Earth   dense iron core, solid at its center, molten surrounding it 22  the thick layer of rock surrounding the core is called the mantle  in the upper mantle, the asthenosphere is soft rock, near its melting point or molten  the harder rock above the asthenosphere is called the lithosphere the crust floats on top of the upper mantle and convection moves large plates of the lithosphere (tectonic plates) along it surface o intense heat rises from core to mantle to crust  mantle rock is pushed upwards as it warms and downward as it cools (convection current)  as the mantle moves it drags large plates of lithosphere along its surface (plate tectonics) Interior Structure Drives Plate Tectonics  plate tectonics drive the shape and geography of oceans and continents    divergent plate boundary: tectonic plates move apart from one another o magma rises upwards and forms new crust as it cools and solidifies o example: Mid-Atlantic Ridge; Iceland is a volcanic island built when magma from underwater volcanoes along the Mid-Atlantic Ridge extruded above the ocean surface and cooled  a fault is a fracture in earth’s crust along which the blocks of rocks on either side are displaced relative to one another o where 2 plates meet along a strike-slip fault, they slip and grind against eachother horizontally, in opposite directions  creates friction which causes earthquakes o plate boundaries that are marked by strike-slip fault are called transform plate boundaries 23  convergent plate boundaries: tectonic plates come together o subduction occurs: dense oceanic plates descend into mantle  the subducted plate is heated and pressurized as it sinks  water vapour escapes helping to melt the overlaying rock  the molten rock rises and this magma may erupt through the surface in the form of volcanoes o subduction of oceanic lithosphere under oceanic lithosphere = result in volcanic islands (called volcanic arc) o subduction of oceanic lithosphere under continental lithosphere = volcanic mountain ranges parallel to the coastlines  example: the Andes Mountains are formed by the Nazca Plate being subducted under the South American Plate  continental collision: when 2 plates of continental lithosphere converge, the continental crust on both ides resists and instead crushes together, bending and buckling and deforming layers of rock from both plates o accumulated masses of buckled crust are forced upward as they are pressed together = mountain ranges o The Himalayas continue to rise today as the Indian-Australian Plate and the Eurasian plate continue to converge   red triangles represent active volcanoes and grey shaded areas are earthquake prone areas  the ring of fire matches the plate boundaries CHAPTER 15: Global Climate Change and CHAPTER 14: Atmospheric Science and Air Pollution (chapters are combined in the slides) Basics of Energy and Climate  A warm substance is warm because it holds more energy than a cold substance  If a warm substance becomes colder, it is because energy is leavin the substance  In a steady-state Earth, incoming energy = outgoing energy over a year  If this is not true, the Earth will either warm up or cool down  Earth’s climate is all about energy fluxes and the balance between outgoing and incoming energy  Energy cannot be created or destroyed, just transferred 24  climate: describes an area’s long-term atmospheric conditions including temperature, moisture content, wind, precipitation, barometric pressure, solar radiation and other characteristics  global climate change describes trends and variations in Earth’s climate involving aspects such as temperature, precipitation and storm frequency and intensity Earth is Open to Energy  Insolation is energy received from the sun  INcoming SOLar radiation  Insolation is shortwave radiation which includes: UV, visible light, and near infrared wavelengths  Insolation drives most processes on Earth  Insolation and Earth’s tilt and rotation produce the daily, seasonal and annual patterns of day length and climate  As the surface of the Earth absorbs short wavelength solar radiation, surface materials increase in temperature and emit infrared radiation  radiation with LONGER wavelength than visible light Seasons   the seasons occur because the Earth is tilted on its axis at a 23.5 degree angle  as the Earth revolves around the Sun, the Northern Hemisphere tilts towards the Sun for one half of the year and the Southern hemisphere tilts towards the Sun for the other half of the year  summer occurs during the period where the hemisphere is tilted toward the Sun Electromagnetic Radiation  Wavelength: electromagnetic radiation travels in waves 25  The distance between wave peaks is called the wavelength Why is Insolation Short Wave Radiation?  Wien’s displacement law: wavelength at which maximum energy radiation occurs is inversely related to surface temperature 2897 l max =  T λ = maximum radiation wavelength (in μm) max T = temperature of surface in degrees K.   Electromagnetic Spectrum  Energy Flux  The rate (amount per time) of energy (joules) received at a surface is called Power (J/s = Watt) 2  Power per surface area is an Energy flux and is measured in W/m  The rate of energy emitted by a substance is governed by the Stefan-Boltzmann Law  QR= εσT where σ=5.67 x 10W/m K 4  And ε is the emissivity factor = how well a surface can emit energy  a black body has perfect emissivity Solar Constant  Definition: the rate at which insolation is received at the outer atmosphere of the Earth  Solar constant = 1367W/m  Energy hitting the Earth averages 342 W/m 26   this occurs because the energy “wave” that hits the earth from the Sun has to spread over a larger area once it hits the Earth itself  so you have the area of a circle spreading over the area of a sphere Latitude Controls   at the poles, the sun’s rays do not hit the Earth directly, they hit at an angle, so the energy is spread over a slightly larger area than at the equator  also, a the poles, the sunlight must travel a longer distance when it hits at the poles (at a lower angles)  so more energy is absorbed and reflected by the atmospheric layers than the sunlight that travels a shorter distance and hits the equator Earth’s Energy Balance  27  yellow – shortwave radiation coming to Earth from Sun  red – long wave transferred away from Earth (reemitted)  about 50% of insolation is absorbed by the Earth  without the greenhouse gas effect, we would be really cold o greenhouse gases such as O , CO an3 N O 2bsorb i2frared radiation really well o some of the energy is re-emitted into space, and some of travels back downwards towards the earth (back radiation) warming the troposphere = greenhouse gas effect Albedo and Available Energy  Earth reflects about 30% of insolation it receives and another 20% is absorbed by the atmosphere  This reflectivity is called albedo (0≤α≤1)  Albedo is related to a substance’s properties: snow has high albedo (0.8-0.95) whereas asphalt has low albedo (0.05-0.1)  Dark coloured or rough things have low albedo (absorb more energy than they reflect)  The 50% of available energy that Earth absorbs goes toward important processes like photosynthesis and driving our climate (i.e. through evaporation, winds etc.) What happens to the energy?  3 main uses of the 70% of insolation that is absorbed by Earth o heating the ground = ground heat flux o providing warmth = sensible heat flux o changing phases of water = latent heat flux  sensible and ground heat can be measured by a thermometer whereas latent heat cannot  it is hidden energy  it takes more energy to change water at 100 degrees into water vapour at 100 degrees than change ice to water because of latent heat  there are a lot more H bonds between water molecules to be broken than there are between ice molecules low latent heat - no water to change phase of why it is very warmflux - which is Oasis! Desert! high latent heat flux - trying to evaporate the water makes a big differencel of water in the distribution of ththe oasis is not as hotin radiation/heat as the rest of the desert  28  in the desert = low latent heat because there is no water to change the phase of, and there is high sensible heat flux  very hot  in the oasis = high latent heat flux because trying to evaporate the pool of water and low sensible heat  in the oasis it is not as hot as in the rest of the desert  water makes a big difference in the distribution of heat/radiation  the partitioning of energy, especially toward latent energy is fundamental to global hydrology 29 Lecture 5: Chapter 3, Chapter 12, Chapter 14 9/10/2013 4:07:00 PM Lecture 5 - CHAPTER 3: Environmental systems and Ecosystem Ecology Hydrology  The partitioning of energy, especially toward latent energy, is fundamental to global hydrology  Definition: the science of water, its global circulation, distribution and properties  specifically water at, near or below the Earth’s surface  Hydrologic cycle: a simplified model of the flow of water, ice, and water vapour from place to place  Less than 1% of the plante’s water is in a form which we can use (freshwater, groundwater, and rain) The Hydrologic Cycle   Precipitation: the condensation of water vapour in the atmosphere resulting in its return to Earth’s surface  Evapotranspiration: the release of water into the atmosphere through a combination of phase change from open surfaces and release of water vapour by plants o o key controls: energy, gradient in vapour pressure, wind and resistance from plants  Infiltration: penetration of water through the soil surface  Runoff: the flow of water across or under the Earth’s surface under the force of gravity 30 o  Groundwater flow: the movement of water beneath the water table to recharge the underground reservoirs called aquifers Key Points about the Global Hydrologic Cycle  More water evaporates from the ocean than is returned by precipitation  More water is returned to the surface of continents by precipitation than is lost via evapotranspiration  The imbalance in the 2 points above are resolved by runoff of water from continents to oceans What is needed for it to rain?  Air needs to cool enough such that water will condense  the temperature at which a given parcel of air becomes saturated is the dew point  Particles must be present in the atmosphere onto which water can condense  called condensation nuclei  Water droplets must grow to a sufficient size such that they do not evaporate entirely before reaching the ground  The key point is cooling air o  vapour pressure: the partial pressure of water in the atmosphere Air Cooling  Air cools by lifting  Convective lifting 31 o  Orographic lifting o  air mass must overcome obstacle so rises  precipitation occurs  once over the mountain (it has already rained) so it descendts as it warms  Frontal lifting o  front: the boundary between air masses that differ in temperature and moisture (and density)  warm front: warm air of warm front rises over the cold front  cools and condenses and form clouds and may produce light rain  cold front: since the cold front is denser it wedges beneath the warm air  the warmer air rises and expands  cools and produces clouds  can result in thunderstorms and even tornadoes 32  once a cold front passes through the sky clears and temperature and humidity usually drop  high pressure system: contains air that moves outward away from center of high pressure as it descends  bring fair weather  low pressure system: air moves toward the low atmospheric pressure at the center of the system and spirals upwards  air expands and cools = precipitation occurs  vertical mixing occurs as air cools and rises but sometimes cold air occurs beneath a layer of warm air  because cold air is denser, it resists vertical mixing and temperatures remain stable  called thermal inversion 33 Lecture 6: Chapter 4 and Chapter 9 9/10/2013 4:07:00 PM Lecture 6 - Biodiversity and Conservation What is Biodiversity?  Biodiversity or biological diversity is the total variety of all organisms in an area  This takes into account the diversity of species, their genes, their populations, habitats and communities  1.8 million species described so far  real number estimated to be closer to 14 million (many remain to be discovered) How do Species become Diverse?  New species come to be about via speciation  This can happen in a number of ways, but the main way is allopatric speciation o Emergence of a new species as a result of the physical separation of populations over some geographic distance o This separation needs to be for a very long time  1000s of generations  Different populations become different species when they can no longer reproduce with one another How can this separation occur?  Mountain uplift can separate 2 valleys  The movement of massive ice sheets or changes in the course of major rivers break up different areas of a continent  Sea level rise, creating new islands  Formation of islands in the oceans by volcanoes  Changes in ocean currents  Drier climate divides a large single lake into several smaller isolated lakes  Manmade islands Divergence of Organisms through History   phylogenetic trees show the history of life’s divergence and illustrate relationships between groups of organisms inferred from the study of similarities and differences  each branch = speciation event  time proceeds from bottom  top  by mapping traits onto phylogenetic trees, biologists can study how traits have evolved over time CHAPTER 9: Conservation of Species and Habitats Classification of Organisms o The categorization of different organisms is taxonomy and is conducted by taxonomists 34 o Organisms with similar appearances and genetic makeup are classified into a hierarchy of categories that reflect evolutionary relationships o Genus – species scientific naming system  example: Ursus maritimus (polar bear) Nomenclature  Scientific names provide information about how species are related to one another  something common names do NOT Species Diversity: Richness and  There can be dozens of English common names for a single species, same name for many species, species without names, derogatory names, unprofessional names! Evenness Species Richness: number of different species in an area. Speciation  There are several measures increases richness. Extinction decreases species richness.  Species diversity Immigration can also increase richness; Emigration or Extirpation (local species extinction) can also decrease it.sity  Variety of DNA (genes) within the species Evenness: extent to which populationonumEcosystem diversity of each  Number and variety of ecosystems different species are equal or not. Species Diversity: Richness and Evenness  Species richness: number of different species in an area o Speciation increases richness o Extinction decreases species richness o Immigration can also increase species richness o Emigration or extirpation (local species extinction) can decrease species richness  Evenness: extent to which population numbers of individuals of each different species are equal or not  10 o box a has increased richness while box b has decreased evenness Genetic Diversity  Refers to the variety in DNA present among individuals within species, subspecies and populations 35  Greater genetic diversity within species helps long term persistence by allowing for better coping with environmental change  higher chance that the population will adapt to changing environment and survive  Genetic bottleneck: following a large drop in population where there is a limited genetic diversity left over to be passed along by the small number of individuals to their descendants o Even if population numbers increase, the genetic diversity is still extremely low, leaving the recovered population susceptible to environmental change Tasmanian Devil Facial Tumour Disease  Infectious cancer threatening the survival of the Tasmanian Devil  Transmitted through fighting and feeding  This is very unusual  cancer cells are usually recognize as foreign and destroyed by the immune system  The Tasmanian devil’s predicament is the result of their extreme genetic similarity  when cells are passed from one to another, because they are so genetically similar, the immune system does not recognize the cancer cells as foreign  A recently discovered resistant population may help save the species Ecosystem Diversity  Refers to the number and variety of ecosystems in a given area based on differences in climate, topography, soil type or other physical factors  A wide variety of ecosystems and habitats provides opportunities for species to specialize/speciate  leads to greater species diversity  At ecotones, where 2 habitats meet and slightly overlap, biodiversity is usually particularly higher than in the different ecosystems Species we know about Species we know about  Lecture 6 – Biodiversity and Conservation 36 14  ¾ of the known species are animals  ¾ of animals are insects  only about 4% are invertebrates  out of all invertebrates, ½ are fish  only 9% of 4% are mammals Biodiversity Unevenly Distributed  Biodiversity is unevenly distributed around the globe  Tropical areas have very high diversity  Arctic areas have very low diversity  In between areas = gradient fromWhy? to high   Temperate and polar latitudes  variable climate favours fewer species that are widespread generalists (can survive a wide range of conditions  they have expansive niches so they can spread out over large areas) Lecture 6 – Biodiversity and Conservation 16  Tropical latitudes  greater insolation, heat and humidity promote more plant growth to support more organisms o Stable climate favours specialist species (species with specific niches) o Together, encourage greater diversity Loss of Biodiversity  Extinction: species ceases to exist  example: Dodo bird  Extirpation: loss of a species from a particular area  Endangered: in imminent danger of becoming extinct or extirpated  example: the wolverine in Canada  Threatened: likely to become endangered in the near future  example: the phantom orchid in Canada Mass Extinctions in Fossil Record  Extinction is a natural process, but current rates of extinction are much higher than normal 37   the fossil record shows evidence of 5 mass extinctions during the past ½ billion years  at the end of each period 50-95% of the world’s species became extinct  each time, biodiversity rebounded to equal or higher levels, but the rebound requires millions of years in each case th 6 Mass Extinction Currently? 6 Mass Extinction Currently?   the human hunter icons are sized according to the degree of evidence of human hunting  larger icons means higher certainty we were the cause of extinction Lecture 6 – Biodiversity and Conservation 19  the time indicates our arrival in that area (approx.) Major Causes of Biodiversity Loss  Habitat alteration  human activity  Introduction of invasive species  drives native species to extinction  Pollution  degrade ecosystems and harm organisms  Overharvesting  population reduction by hunting (example: polar bears) can lead to the species extinction because some species are not as able to bring their numbers back up (polar bears only have a few young in their life time and they take a long time to reach sexual maturity  process of “making more” is too slow to compensate for hunting) 38  Climate change  affect both plants and animals, putting increasing stress on both and eventually may lead to extinction of species in certain places Loss of Biodiversity = Loss of Ecosystem Services  Many of the things critical to our lives are “free” ecosystem services provided by the environment, which we generally take for granted  According to UNEP biodiversity: o Provides food, fuel and fibre o Provides shelter and building materials o Purifies air and water o Detoxifies and decomposes wastes o Moderates floods, droughts, wind o Generates and renews soil fertility o Controls pests and disease o Allows us to adapt to change Other Key Consequences of Biodiversity Loss  Loss of ecosystem functioning o Keystone species: a species that has a disproportionately large effect on its environment relative to its abundance o Ecosystem engineers: creates or modifies habitats  Lesser food security  Loss of potential medicines  Loss of eco-tourism  Loss of nice places to sit and think Conserving Species  Maintaining habitat (in situ conservation) is key, but change can be irreversible and other options must be considered  Ex situ conservation includes trying to preserve species in zoo, aquaria, seed banks, arboretums, and other organism “archives”  Captive breeding: breeding and raising of individual species in zoos and botanical gardens with the intent of reintroducing them into the wild Biodiversity Hot Spots 39 Biodiversity Hot Spots   34 biodiversity hot spots used to cover about 16% of land surface  now only about 2.3% • 34 biodiversity hot spots used to cover ~16% of land surface,e here but now only about 2.3%. • 50% of all plants and 42% of all terrestrial vertebrates live here. Lecture 6 – Biodiversity and Conservation 24 Parks, Refuges, Land Trusts  Protection of biodiversity is one reason for setting aside land as a park  43 national parks in Canada (soon to be 44  Rouge National Park) = they cover 2.7% of area  wildlife refuges are areas conserved for wildlife and habitat but also sometimes open for hunting, fishing, hiking etc. o hunters and other sportsmen mostly at the forefront of conservation  land trusts, like the Nature Conservancy, are private nonprofit groups that purchase land to preserve it Biosphere Reserves Biosphere Reserves  Biosphere reserves are tracts of land with exceptional biodiversity that couple preservation with sustainable development so that there are benefits to local people  Have particular spatial structure • Biosphere reserves are tracts of land with exceptional biodiversity that couple preservation with sustainable development so that  there are benefits to  includes core area that preserves biodiversity, a buffer zone that allows limited development and a transition zone that permits various uses local people. • Have particular spatial Conservation is not easy structure.  What works for one country or culture may not work for another – and many species cross national boundaries Lecture 6 – Biodiversity and Conservation 26 40  Lack of funding, expertise, priority in areas with highest remaining diversity  Hard questions about how to conserve species  what do they need to survive? What does the growing human population need?  Soft questions about social equity, developed vs. undeveloped countries, determining ownership, logistics, politics, and of course funding! Lichen Diversity Conservation in Lichen Diversity Conservation in Scotland Scotland  Tentsmui Forest in Fife, Scotland • Tentsmuir Forest in Fife,  Commercial forest established around 1920 on former sand dunes, fields  How many lichens live there? How can the forest be used to conserve them while still producing timber? Scotland
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