EESA01Fall2012 Lectures 1 -3 Notes

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Environmental Science
Carl Mitchell

Lecture 3 – Chapter 3 12/12/2012 12:46:00 PM LECTURE 1: 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we are still protecting and preserving it  Stock is the harvestable portion of the resource  if resources are being withdrawn from the stock at higher rates than it is being replenished, then the stock will eventually be depleted  Non-renewable : in finite supply and are depleatable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 2  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 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 3  An experiment involves manipulating variables  scientist manipulates the independent variable while keeping the dependant variable constant 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 4  Recycling  Renewable energy like solar and wind power  Best management practices in natural resource extraction and agriculture  All of these practical solutions though are very costly $$ Lecture 2 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 tD= = growthrate(%) growthrate(%)  5  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 6  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  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 7  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 9  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)
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