《环境科学与工程导论（Introduction to environmental science and engineering）》课程教案
教学内容：分三个模块（Part I, Part II 和 Part III，Part IV），12个单元完成。
第一章 绪论（INTRODUCTION TO ENVIRONMENTAL SCIENCE ）（2学时）
Environmental Science is an applied science, based on the interdisciplinary study of how humanity affects other living organisms and the nonliving physical environment. It uses information from many disciplines from the hard sciences, including biology (ecology, especially), chemistry, geology, and physics, as well as from problem solving fields, such as economics, politics, and social science.
As Earth’s human population continues to grow, as technology advances and human needs and wants increase, our impacts on the world become more widespread and severe, despite improvement in some areas. Environmental impacts, in turn, affect human health and well being.
A few of the major challenges that are topics for environmental science include:
& #9674; Global Climate Change (global warming and all of its consequences)
& #9674; Management of Earth's water resources
& #9674; Energy and mineral resource depletion
& #9674; Meeting the food, fiber and clothing needs of a growing World population
& #9674; Air pollution and acid deposition (rain)
& #9674; Stratospheric ozone depletion
& #9674; Water pollution
& #9674; Soil erosion, fertility depletion and contamination
& #9674; Deforestation
& #9674; The loss of fisheries
& #9674; Accelerated damage to coral reefs
& #9674; Habitat destruction on land and in the oceans
& #9674; The spread of infectious diseases, including those caused by organisms that have developed antibiotic resistance
& #9674; Long term sustainability of the Global and national economies
& #9674; The evolution and spread of pests that are resistant to pesticides
& #9674; Waste generation and disposal in a world increasing in population and per capita consumption
& #9674; The fate of hazardous chemicals in the environment
& #9674; Potential environmental effects of genetic engineering
& #9674; Protection of the Ocean and its resources
All of the above and other environmental challenges are multidisciplinary in nature. That is, in order to understand each environmental challenge sufficiently well to develop viable solutions, scientists must assemble expertise in several disciplines.
At a minimum, the well trained environmental scientist will be conversant in physics, chemistry, biology, ecology and geology (Earth Science). The environmental scientist will also be familiar with the relevant economic, social and political science, because all three are essential to understanding not only how humans come to affect the environment, but also what options are available for action, because technical fixes will rarely, if ever, solve an environmental problem once and for all. Politics, economics and cultural adjustment will each contribute its share to any viable solution.
A. Observations and Questions:
B. Hypothesis: Making inferences
C. Controlled experiment
D. Analyze Result
E. Report Results/Second Hypothesis
F. Theories in science
1．在进入第一章节的学习时，板书(或幻灯片)特别说明本课程的学习目标（OBJECTIVES OF THIS COURSE）：
After completing this lesson, you will be able to:
& #8226; explain how ecological balance is maintained in nature;
& #8226; list some environmental problems (natural and man-made);
& #8226; explain the causes, effects and control of deforestation and desertification
& #8226; explain the impact of increasing human population on the environment;
& #8226; define pollution and list types of pollutants;
& #8226; list the sources, consequences and means of control of air, water, soil and noise pollution;
& #8226; explain the causes and effects of global warming, acid rain, ozone layer depletion and other international environmental problems;
& #8226; classify and define waste into biodegradable and non-biodegradable type.
2. 板书(或幻灯片)说明本章学习目标（Learning Objectives）：
When you are finished with this chapter you should be able to:
& #8226; Define environmental science
& #8226; Describe the major challenges that are topics for environmental science .
& #8226; Name and describe the steps of the scientific method.
Describe the importance of science in society’s environmental decisions.
环境(Environment)；环境问题（Environmental problem）；环境破坏（Environmental disturbance）；环境污染（Environmental pollution）；
A. Observations and Questions:
B. Hypothesis: Making inferences
C. Controlled experiment
D. Analyze Result
E. Report Results/Second Hypothesis
F. Theories in science
A. Scientific Assessment
B. Risk Analysis
C. Public Education
D. Political Action
E. Scientific Follow Up
Case Study I: Lake Washington
Case Study II：湖南省 重金属血Pb污染
PART I MAINTENANCE OF ECOLOGICAL BALANCE IN NATURE
第二章 生态平衡（ECOLOGICAL BALANCE ）
2.1 ECOLOGYIn order to understand the term ecological balance, it is necessary to know what is meant by ecology. Ecology is the relationship between organisms and their environment.
The Daintree Rainforest in Queensland, Australia is an example of a forest ecosystem.
A central principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. The sum total of interacting living organisms (the biocoenosis) and their non-living environment (the biotope) in an area is termed an ecosystem. Studies of ecosystems usually focus on the movement of energy and matter through the system.
Ecosystems can be roughly divided into terrestrial ecosystems (including forest ecosystems, steppes, savannas, and so on), freshwater ecosystems (lakes, ponds and rivers), and marine ecosystems, depending on the dominant biotope.
Much attention has been given to preserving the natural characteristics of Hopetoun Falls, Australia, while allowing ample access for visitors.
Ecological factors that affect dynamic change in a population or species in a given ecology or environment are usually divided into two groups: abiotic and biotic.
Abiotic factors are geological, geographical, hydrological, and climatological parameters. A biotope is an environmentally uniform region characterized by a particular set of abiotic ecological factors.
Biocenose, or community, is a group of populations of plants, animals, microorganisms. Each population is the result of procreations between individuals of the same species and cohabitation in a given place and for a given time. When a population consists of an insufficient number of individuals, that population is threatened with extinction; the extinction of a species can approach when all biocenoses composed of individuals of the species are in decline. In small populations, consanguinity (inbreeding) can result in reduced genetic diversity, which can further weaken the biocenose.
Biotic ecological factors also influence biocenose viability; these factors are considered as either intraspecific or interspecific relations.
Ecosystems are not isolated from each other, but are interrelated. For example, water may circulate between ecosystems by means of a river or ocean current. Water itself, as a liquid medium, even defines ecosystems. Some species, such as salmon or freshwater eels, move between marine systems and fresh-water systems. These relationships between the ecosystems lead to the concept of a biome.
A biome is a homogeneous ecological formation that exists over a large region, such as tundra or steppes. The biosphere comprises all of the Earth's biomes -- the entirety of places where life is possible -- from the highest mountains to the depths of the oceans.
Biomes correspond rather well to subdivisions distributed along the latitudes, from the equator towards the poles, with differences based on the physical environment (for example, oceans or mountain ranges) and the climate. Their variation is generally related to the distribution of species according to their ability to tolerate temperature, dryness, or both. For example, one may find photosynthetic algae only in the photic part of the ocean (where light penetrates), whereas conifers are mostly found in mountains.
In an ecosystem, the connections between species are generally related to their role in the food chain. There are three categories of organisms:
These relations form sequences, in which each individual consumes the preceding one and is consumed by the one following, in what are called food chains or food networks. In a food network, there will be fewer organisms at each level as one follows the links of the network up the chain, forming a pyramid.
These concepts lead to the idea of biomass (the total living matter in an ecosystem), primary productivity (the increase in organic compounds), and secondary productivity (the living matter produced by consumers and the decomposers in a given time).
2.2.5 AN ECOLOGICAL PYRAMID
These last two ideas are key, since they make it possible to evaluate the carrying capacity -- the number of organisms that can be supported by a given ecosystem. In any food network, the energy contained in the level of the producers is not completely transferred to the consumers. The higher up the chain, the more energy and resources are lost. Thus, from a purely energy and nutrient point of view, it is more efficient for humans to be primary consumers (to subsist from vegetables, grains, legumes, fruit, etc.) than to be secondary consumers (consuming herbivores, omnivores, or their products) and still more so than as a tertiary consumer (consuming carnivores, omnivores, or their products). An ecosystem is unstable when the carrying capacity is overrun.
The total productivity of ecosystems is sometimes estimated by comparing three types of land-based ecosystems and the total of aquatic ecosystems. Slightly over half of primary production is estimated to occur on land, and the rest in the ocean.
Humanity's actions over the last few centuries have seriously reduced the amount of the Earth covered by forests (deforestation), and have increased agro-ecosystems. In recent decades, an increase in the areas occupied by extreme ecosystems has occurred, such as desertification.
Generally, an ecological crisis occurs with the loss of adaptive capacity when the resilience of an environment or of a species or a population evolves in a way unfavourable to coping with perturbations that interfere with that ecosystem, landscape or species survival (Note: The concept of resilience is not universally accepted in ecology, and moreso represents a contingent within the field that take a holist view of the environment.
Ecological crises vary in length and severity, occurring within a few months or taking as long as a few million years. They can also be of natural or anthropic origin. They may relate to one unique species or to many species, as in an Extinction event. Lastly, an ecological crisis may be local (as an oil spill) or global (a rise in the sea level due to global warming).
2.3 ECOLOGICAL BALANCEDue to the increases in technology and a rapidly increasing population, humans have more influence on their own environment than any other ecosystem engineer.In nature, ecological balance is a state where one species does not dominate over all others, and every plant and animal finds its own ecological home. In other words, ecological balance is a state of balance of nature in which a variety of species remain relatively stable, subject to gradual changes through natural course. It is a term for an ideal condition in which the interrelationships of organisms to one another and their environment is harmonious. In reality, the ecological balance is continually upset by natural events.
The rich diversity of life that inhabits the earth helps in maintaining a balanced environment. The perfect balance between the physical environment and the living organisms in nature is called ecological balance. Herbivores eat plants, and are themselves eaten by carnivores. The number of plants, herbivores and carnivores is maintained in such a way that there are enough organisms of different species to survive. However, various human activities cause interference and imbalance in nature. Ecological imbalances may lead to:
& #8226; Destruction of natural habitat of wild life. For example, cutting of forests have resulted in the disappearance of Cheetah, and a falling number of tigers in India.
& #8226; Capturing or killing of lions has led to an increased number of herbivores that compete for grass. They may uproot grass, making the soil barren that may lead to soil erosion and desertification.
& #8226; Disturbance in the food chain, which has resulted in an enormous increase in the population of a particular types of organisms, while others may become endangered.Ecological planning attempts to secure the natural resources (water, soil, and air) the foundations of life for man, flora and fauna. While the cities get denser and larger, a functioning natural balance needs to be guaranteed. Equilibrium areas, especially open spaces, need to be maintained and created to relieve densely populated and polluted areas. Existing ecological pressures can be minimized through a number of different, small measures. We can contribute to achieving this target by cleaning our premises and protecting the environment.The indiscriminate use of pesticides, such as DDT, after World War II first alerted opinion in the Western countries to the delicate nature of the world's ecological system. This was followed by a spate of warnings about other possibilities of ecological disaster. For all his intelligence, man behaves with a lack of respect for his environment that is both short-sighted and potentially suicidal. It is time we wake up from our long slumber and start protecting the environment so that we have a better world to live in and to pass on a cleaner earth for our next generation.
2.4 THE GLOBAL SITUATION
The dominant patterns of production and consumption are causing environmental devastation, the depletion of resources, and a massive extinction of species. Communities are being undermined. The benefits of development are not shared equitably and the gap between rich and poor is widening. Injustice, poverty, ignorance, and violent conflict are widespread and the cause of great suffering. An unprecedented rise in human population has overburdened ecological and social systems. The foundations of global security are threatened. These trends are perilous-but not inevitable.
2.5 THE CHALLENGES AHEAD
The choice is ours: form a global partnership to care for Earth and one another or risk the destruction of ourselves and the diversity of life. Fundamental changes are needed in our values, institutions, and ways of living. We must realize that when basic needs have been met, human development is primarily about being more, not having more. We have the knowledge and technology to provide for all and to reduce our impacts on the environment. The emergence of a global civil society is creating new opportunities to build a democratic and humane world. Our environmental, economic, political, social, and spiritual challenges are interconnected, and together we can forge inclusive solutions.
Prevention is the best method of environmental protection and, when knowledge is limited, apply a precautionary approach:
a. Take action to avoid the possibility of serious or irreversible environmental harm even when scientific knowledge is incomplete or inconclusive.
When you are finished with this session you should be able to:
1) Define ecological balance.
2) Describe the major effects of imbalance on human health and other living things.
3) Describe the ways to keep ecological balance.
4) Describe the importance of keeping ecological balance.
4. 讲授可持续发展社会的构建：Building a sustainable society
第三章 人口问题（POPULATION ISSUES）
Population is growing at an ever-increasing rate over time. Note in particular the times at which human population is estimated to have reached 1, 2, 3, 4 and 5 billion.
The rate at which world population grows is determined at any time solely by the birth rate and the death rate at that point. The rate of growth is calculated by determining the crude birth rate (number of births per 100 people per year) and subtracting from that the crude death rate (number of deaths per 100 people per year). The difference is the growth rate, the annual increase in population, usually expressed as a percentage.
Another convenient way to express the rate at which a population is growing is to calculate it’s doubling time.
The population growth curve is an example of what mathematicians call an exponential curve. A graph such as this shows the increase that occurs in any quantity that is growing at a fixed percentage of its current size. A savings account earning compound interest grows this way, and so does the human population. A convenient way to express exponential growth is in terms of "doubling time," the time it would take for the quantity to double.
& #8226; Where DT = doubling time in years and GR = growth rate in percentage
Populations grow much the same way that money does in a savings account. To calculate the doubling time for population, you would use the same formula.
Current demographic data indicate that the world's population is growing at 1.4%. This rate may not seem ominous, but if we use the same mathematical formula as we did for calculating the doubling time of money, we can determine the doubling time for the world’s population.
Human population growth will ultimately be put in check whether we do anything about it or not. To determine how and when that might happen, we must look to evidence in the non-human world. Most species can live only in certain limited habitats that contain all the specific needs of that species. Each of these habitats has a limit to the number of individuals of a certain species that it can support. That number is known as the Carrying Capacity.
Note that this graph (Fig.3.1) has no numbers on either the x-axis or the y-axis. This is because the numbers would be different for each species in each environment, however, the overall pattern is correct for most. Basically it indicates that each species has a finite and determinable Carrying Capacity for any specific environment. In almost all cases the Carrying Capacity can be determined through experiment or observation.
It is reasonable to assume that many environments, or habitats, have a carrying capacity for humans as well as for other species, but this limit may be much more difficult to determine. For one thing, humans have the unique ability to make almost any environment habitable, thus making it seem that the earth's carrying capacity for humans is virtually unlimited. For another, it is not practical, nor even ethical, to experiment with human populations in an attempt to determine limits and carrying capacities for humans in specific environments. This does not mean, however, that there are no limits to the number of humans the Earth can sustain.
The limiting factors for all non-human species include:
& #8226; depletion of life-sustaining resources (air, water, food and an energy source)
& #8226; predator/prey relations
& #8226; space
& #8226; ability to dispose of waste
Generally, the Carrying Capacity is reached when a population approaches one of its limiting factors. Experiments in which each of the limiting factors is used as the independent variable can indicate which factor is actually responsible for reaching the Carrying Capacity. Even though the Carrying Capacity for humans is unknown, it is surely not unlimited. There must be some specific number of humans which the Earth can sustain, and that number will be determined by one the limiting factors previously discussed:
The limiting factors for the human species include:
& #8226; depletion of one of the life-sustaining resources (air, water, food or energy)
& #8226; predator/prey relations (probably limited to disease, in the case of humans)
& #8226; space
& #8226; ability to dispose of waste, and
& #8226; poisoning of life-sustaining resources by pollution
Continued high global population growth rates have an impact on all of the Earth’s sub-systems:
· The Solid Earth - through non-renewable resource consumption and depletion, waste disposal and land degradation
& #8226; deforestation,
& #8226; destruction of wild life,
& #8226; air, water and land pollution,
& #8226; diminishing fossil fuels (oil, coal and natural gas),
& #8226; concentration of pesticides in alarming proportions in organisms, and
& #8226; depletion of ozone layer and global warming.
Population control is clearly needed if we are to live sustainably.
6. 要掌握的概念：Birth Rate， Death Rate, Growth Rate.
1. 板书说明本章学习目标（Learning Objectives）：
& #8226; define the terms—population, birth rate, death rate, and growth rate, doubling time , Carrying capacity ;
& #8226; draw and explain the growth curves;
& #8226; trace the trend for rise in World , China and Indian population;
& #8226; list the disadvantages of over-population;
& #8226; explain the need for controlling population;
2. 图片展示人口增长的规律：几何增长。介绍 Doubling time: the time it would take for the quantity of population to double
4. 介绍中国的计划生育政策(family planning: one-child policy)
介绍中国人口特点（动画展示中国人口结构变迁）， 老龄化的社会问题(aging or aged society)
5. 重点讲述：人口与环境的关系：人口快速增长所带来的环境问题 (effects of over- population on the environment)。
第四章 能源与环境保护（ENERGY RESOURCES）
Energy comes in different forms -- heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy.
There are two types of energy – stored (potential) energy and working (kinetic) energy. All forms of energy are stored in different ways, in the energy sources that we use every day. These sources are divided into two groups: renewable and non-renewable.
4.2 NON-RENEWABLE ENERGY
Non-renewable energy is an energy source that we are using up and cannot recreate in a short period of time. That is this kind of sources will eventually run out.
we get most of our energy from nonrenewable energy sources, which include the fossil fuels--oil, natural gas, and coal. They're called fossil fuels because they were formed over millions and millions of years by the action of heat from the Earth's core and pressure from rock and soil on the remains (or "fossils") of dead plants and animals. Another nonrenewable energy source is the element uranium, whose atoms we split (through a process called nuclear fission) to create heat and ultimately electricity.
4.3 RENEWABLE ENERGY
As we realize more and more that fossil fuels are going to run out, we're trying harder to develop other means of generating the electricity on which we depend.
Renewable energy is an energy source that we can use over and over again. It means that it won't run out.
Renewable energy sources include solar energy, which comes from the sun and can be turned into electricity and heat. Wind, geothermal energy from inside the earth, biomass from plants, and hydropower from water are also renewable energy sources.
Basic concept of alternative energy sources relates to issues of sustainability, renewability and pollution reduction Despite this, deliverable cost to the consumer still drives everything which becomes a large barrier.
In reality, Alternative Energy means anything other than deriving energy via Fossil Fuel combustion. Since 90% of our current energy usage is derived from fossil fuels and since there is only 50--70 years of production left in that resource then there is a clear need to invest in alternative energy sources NOW not later.
Basic Barrier to all forms of alternative energy lies in high initial costs and long payback times. This is the fluourescent lightbulb syndrome on a much larger scale.
This can only be solved if we have a subsidy program that allows startup companies to have long pay back times. Possibly, the current move toward energy deregulation will create this kind of framework.
Advantages: Always there; no pollution
Disadvantages: Low efficiency (15%) which can only be compensated for by large collecting areas; significant generation of waste heat ; Very high initial costs; lack of adequate storage materials (batteries); High cost to the consumer although these costs are going down. Current levelized cost is 20-25 cents per KWH.
Advantages: No pollution; Very high efficieny (80%); little waste heat; low cost per KWH (4.5 cents); can adjust KWH output to peak loads; recreation dollars
Disadvantages: Fish are endangered species; Sediment buildup and dam failure; changes watershed characteristics; alters hydrological cycle
Advantages: none on large scale; supplemental power in windy areas; best alternative for individual homeowner or a regional consortium. In SE Minnesota, Wind Energy is feed into the power grid and sold to the consumer for 4.5 cents per KWH.
Disadvantages: Highly variable source; relatively low efficiency (30%); un- aesthetic (visual pollution); disruption of migratory birds (note this is what killed the recently proposed Columbia River Gorge wind turbine project).
Advantages: very high efficiency; low initial costs since you already got steam
Disadvantages: non-renewable (more is taken out than can be put in by nature); highly local resource (EWEB recently abandoned its proposed 10 MegaWatt Facility and Newberry Crater as the geothermal yield was lower than originally thought)
188.8.131.52 OCEAN THERMAL ENERGY CONVERSION
Advantages: enormous energy flows; steady flow for decades; can be used on large scale; exploits natural temperature gradients in the ocean
Disadvantages: Enormous engineering effort; Extremely high cost; Damage to coastal environments?
184.108.40.206 TIDAL ENERGY
Advantages: Steady source; energy extracted from the potential and kinetic energy of the earth-sun-moon system; can exploit bore tides for maximum efficiency.
Disadvantages: low duty cycle due to intermittent tidal flow; huge modification of coastal environment; very high costs for low duty cycle source.
220.127.116.11 BIOMASS ENERGY
Biomass is the organic matter in trees, agricultural crops and other living plant material. It is made up of carbohydrates — organic compounds that are formed in growing plant life. Ever since the earliest inhabitants of the region burned wood in their campfires for heat, biomass has been a source of energy for meeting human needs in the Pacific Northwest.
Today, new ways of using biomass are still being discovered. One way is to produce ethanol, a liquid alcohol fuel. Ethanol can be used in special types of cars that are made for using alcohol fuel instead of gasoline. The alcohol can also be combined with gasoline. This reduces our dependence on oil - a non-renewable fossil fuel.
本章采用小组讨论的教学方式。在介绍各种可替代能源的基础上，为每一个小组分配一种替代能源，在小组内讨论这种能源的开发和利用带来的正面和负面的环境影响（advantages and disadvantages）。
& #8226; (Teamwork of groups: Discussion ):
& #8226; Group 1: Solar energy
& #8226; Group 2: wind energy
& #8226; Group 3: Geothermal energy
& #8226; Group 4: Nuclear energy_ nuclear fission
& #8226; Group 5: Nuclear energy_ nuclear fusion
& #8226; Group 6: Biomass energy
& #8226; Group 7: hydroelectricity (energy)
& #8226; Group 8: Hydrogen energy
& #8226; Group 9: Ground thermal (heat pump system) energy
& #8226; Group 10: Tidal energy
1. 板书说明本章学习目标（Learning Objectives）：
When you are finished with this session you should be able to:
& #8226; Define energy, fossil fuel, clean energy, alternative energy and renewable energy.
& #8226; Describe the major effects of energy exploration on human health and other living things.
& #8226; Describe the advantage and disadvantage of each type of energy use.
& #8226; Describe the importance of saving energy.
Biological diversity, or the shorter "biodiversity," simply means the diversity, or variety, of plants and animals and other living things in a particular area or region. For instance, the species that inhabit Los Angeles are different from those in San Francisco, and desert plants and animals have different characteristics and needs than those in the mountains, even though some of the same species can be found in all of those areas.
Biodiversity also means the number, or abundance of different species living within a particular region. Scientists sometimes refer to the biodiversity of an ecosystem, a natural area made up of a community of plants, animals, and other living things in a particular physical and chemical environment.
In practice, "biodiversity" suggests sustaining the diversity of species in each ecosystem as we plan human activities that affect the use of the land and natural resources.
The number of species of plants, animals, and microorganisms, the enormous diversity of genes in these species, the different ecosystems on the planet, such as deserts, rainforests and coral reefs are all part of a biologically diverse Earth. Appropriate conservation and sustainable development strategies attempt to recognize this as being integral to any approach. Almost all cultures have in some way or form recognized the importance that nature, and its biological diversity has had upon them and the need to maintain it. Yet, power, greed and politics have affected the precarious balance.
Biodiversity actually boosts ecosystem productivity where each species, no matter how small, all have an important role to play and that it is this combination that enables the ecosystem to possess the ability to prevent and recover from a variety of disasters. This is obviously useful for mankind as a larger number of species of plants means more variety of crops and a larger number of species of animals ensure that the ecosystem is naturally sustained.
And so, while we dominate this planet, we still need to preserve the diversity in wildlife.
A healthy biodiversity provides a number of natural services for everyone:
Ecosystem services, such as
o Protection of water resources
o Soils formation and protection
o Nutrient storage and recycling
o Pollution breakdown and absorption
o Contribution to climate stability
o Maintenance of ecosystems
o Recovery from unpredictable events
Biological resources, such as
o Medicinal resources and pharmaceutical drugs
o Wood products
o Ornamental plants
o Breeding stocks, population reservoirs
o Future resources
o Diversity in genes, species and ecosystems
Social benefits, such as
o Research, education and monitoring
o Recreation and tourism
o Cultural values
The February 1999 Biodiversity Protocol meeting in Colombia broke down because USA, not even a signatory to the Convention on Biological Diversity, to which the protocol is meant to be part of, and five other countries of the "Miami Group" felt that their business interests were threatened. The safety concerns were unfortunately overridden by trade concerns. Some technological advances, especially in genetically engineered food, have been very fast paced and products are being pushed into the market place without having been proven safe. All over the world, concerned citizens and governments have been trying to take precautionary measures. However, 1999 was not a successful year in that respect. Last updated Monday, March 19, 2001.
5.3.2 BIOSAFETY PROTOCOL 2000
A Biosafety Protocol meeting was hosted in Montreal, Canada January 24 to January 28. Compared to the fiasco of the previous year, this time, there had been a somewhat successful treaty to regulate the international transport and release of genetically modified organisms to protect natural biological diversity. However, there were a number of important and serious weaknesses too.
1. 板书说明本章学习目标（Learning Objectives）：
When you are finished with this session you should be able to:
& #8226; Define biodiversity.
& #8226; Describe the major effects of loss of biodiversity on human health and other living things.
& #8226; Describe the major causes of loss of biodiversity.
& #8226; Describe the importance of protection of biodiversity.
4. 要求学生记忆生物多样性的三个层面：生态系统多样性、物种多样性和遗传多样性（Ecosystem diversity, species diversity and genetic diversity.）
PART II INTERNATIONAL ENVIRONMENTAL PROBLEMS
第六章 森林锐减与荒漠化（DEFORESTATION AND DSZERTIFICATION）
CHAPTER 6 DEFORESTATION AND DSZERTIFICATION
Forests cover around a quarter to a third of the total land surface of the Earth. The reduction in area of this valuable environmental, social and economic resource through deforestation has the potential to cause problems on a global scale. Climate models have demonstrated a clear link between deforestation and climate change.
Deforestation is the process of changing land use from forestry to a non-forest use. Western Europe has already lost over 99% of its primary forest. Today, deforestation programmes focus on the major rainforests of the tropics. In the 1980s global deforestation was estimated at 17 to 20 million hectares per year, equivalent to the size of Britain. Current tropical tree planting programmes are not keeping pace with this rate of deforestation. Countries in these areas are often under-developed and striving for improved economies. Deforestation for wood and agricultural land can provide numerous economic benefits, but can have damaging environmental impacts on forest ecosystems and can affect local and regional climate.
Forests absorb a lot of sunlight for photosynthesis, and only about 12 to 15% is reflected. The large amounts of energy absorbed by forests acts to stimulate convection currents in air which enhance the production of rainfall. Tropical rainforests in particular are very wet and humid places. Deforested areas, by contrast, reflect about 20% of incoming sunlight. Deforested areas consequently, can become drier as a result of the loss of vegetation, increasing the risk of desertification. As the area of deforestation increases, so the impact on climate grows.
Trees also absorb carbon dioxide from the atmosphere for photosynthesis, and therefore help to regulate the natural greenhouse effect. Deforestation takes away a potential sink for the carbon dioxide mankind is pumping into the atmosphere. In addition, if forests are removed by burning, a lot of extra carbon dioxide locked up in tree wood is returned to the atmosphere.
The local level is where deforestation has the most immediate effect. With forest loss, the local community loses the system that performed valuable but often underappreciated services like ensuring the regular flow of clean water and protecting the community from flood and drought. The forest acts as a sort of sponge, soaking up rainfall brought by tropical storms while anchoring soils and releasing water at regular intervals. This regulating feature of tropical rainforests can help moderate destructive flood and drought cycles that can occur when forests are cleared.
When forest cover is lost, runoff rapidly flows into streams, elevating river levels and subjecting downstream villages, cities, and agricultural fields to flooding, especially during the rainy season. During the dry season, such areas downstream of deforestation can be prone to months-long droughts which interrupt river navigation, wreak havoc on crops, and disrupt industrial operations.
There is serious concern that widespread deforestation could lead to a significant decline in rainfall and trigger a positive-feedback process of increasing desiccation for neighboring forest cover; reducing its moisture stocks and its vegetation would then further the desiccation effect for the region. Eventually the effect could extend outside the region, affecting important agricultural zones and other watersheds.
A decrease in the total amount of rainfall in arid and semi-arid areas could increase the total area of dry lands worldwide, and thus the total amount of land potentially at risk from desertification.
Desertification was defined at the Rio Earth Summit in 1992 as "land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors including climatic variations and human activities". Desertification involves the depletion of vegetation and soils. Land degradation occurs all over the world, but it is only referred to as desertification when it takes place in drylands. This is because these areas are especially prone to more permanent damage as different areas of degraded land spread and merge together to form desert-like conditions.
Many dryland areas face increasingly low and erratic rainfalls, coupled with soil erosion by wind and the drying up of water resources through increased regional temperatures. Deforestation can also reduce rainfall in certain areas, increasing the threat of desertification. It is not yet possible, using computer models, to identify with an acceptable degree of reliability those parts of the Earth where desertification will occur. Existing drylands, which cover over 40% of the total land area of the world, most significantly in Africa and Asia, will probably be most at risk to climate change. These areas already experience low rainfall, and any that falls is usually in the form of short, erratic, high-intensity storms. In addition such areas also suffer from land degradation due to over-cultivation, overgrazing, deforestation and poor irrigation practices.
The direct physical consequences of desertification may include an increased frequency of sand and dust storms and increased flooding due to inadequate drainage or poor irrigation practices. This can contribute to the removal of topsoil and vital soil nutrients needed for food production, and bring about a loss of vegetation cover which would otherwise have assisted with the removal of carbon dioxide from the atmosphere for plant photosynthesis. Desertification can also initiate regional shifts in climate which may enhance climate changes due to greenhouse gas emissions.
1. 详解本模块学习目的（Learning objectives）：
When you are finished with this part you should be able to:
& #8226; Define global environmental problems , deforestation, desertification, greenhouse effects, global warming, acid deposition and hazardous waste.
& #8226; Describe the mechanisms of greenhouse effects, global warming, depletion of ozone layer, .
& #8226; Determine the greenhouse gas and calculate their GWP-global warming potential.
& #8226; Describe the Effect of deforestation, desertification , depletion of ozone layer, acid deposition and global warming .
& #8226; International co-operation
3. 进入第六章学习内容，说明本章学习目的（Learning Objectives）：
When you are finished with this session you should be able to:
& #8226; Define deforestation and desertification.
& #8226; Describe the major effects of deforestation and desertification on human health and other living things.
& #8226; Describe the major causes of deforestation and desertification.
第七章 全球气候变化（CLIMATE CHANGE）
CHAPTER 7 CLIMATE CHANGE
According to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit in the past century, with accelerated warming during the past two decades. There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide. The heat-trapping property of these gases is undisputed although uncertainties exist about exactly how earth’s climate responds to them.
Energy from the sun drives the earth’s weather and climate, and heats the earth’s surface; in turn, the earth radiates energy back into space. Atmospheric greenhouse gases (water vapor, carbon dioxide, and other gases) trap some of the outgoing energy, retaining heat somewhat like the glass panels of a greenhouse.
Without this natural “greenhouse effect,” temperatures would be much lower than they are now, and life as known today would not be possible. Instead, thanks to greenhouse gases, the earth’s average temperature is a more hospitable 60°F. However, problems may arise when the atmospheric concentration of greenhouse gases increases.
Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth’s atmosphere. Sulfate aerosols, a common air pollutant, cool the atmosphere by reflecting light back into space; however, sulfates are short-lived in the atmosphere and vary regionally.
Estimating future emissions is difficult, because it depends on demographic, economic, technological, policy, and institutional developments. Several emissions scenarios have been developed based on differing projections of these underlying factors. For example, by 2100, in the absence of emissions control policies, carbon dioxide concentrations are projected to be 30-150% higher than today’s levels.
Global mean surface temperatures have increased 0.5-1.0°F since the late 19th century. The 20th century's 10 warmest years all occurred in the last 15 years of the century. Of these, 1998 was the warmest year on record. The snow cover in the Northern Hemisphere and floating ice in the Arctic Ocean have decreased. Globally, sea level has risen 4-8 inches over the past century. Worldwide precipitation over land has increased by about one percent. The frequency of extreme rainfall events has increased throughout much of the United States.
Increasing concentrations of greenhouse gases are likely to accelerate the rate of climate change. Scientists expect that the average global surface temperature could rise 1-4.5°F (0.6-2.5°C) in the next fifty years, and 2.2-10°F (1.4-5.8°C) in the next century, with significant regional variation. Evaporation will increase as the climate warms, which will increase average global precipitation. Soil moisture is likely to decline in many regions, and intense rainstorms are likely to become more frequent. Sea level is likely to rise two feet along most of the U.S. coast.
Calculations of climate change for specific areas are much less reliable than global ones, and it is unclear whether regional climate will become more variable
Like many fields of scientific study, there are uncertainties associated with the science of global warming. This does not imply that all things are equally uncertain. Some aspects of the science are based on well-known physical laws and documented trends, while other aspects range from 'near certainty' to 'big unknowns.'
Scientists know for certain that human activities are changing the composition of Earth's atmosphere. Increasing levels of greenhouse gases, like carbon dioxide (CO2), in the atmosphere since pre-industrial times have been well documented. There is no doubt this atmospheric buildup of carbon dioxide and other greenhouse gases is largely the result of human activities.
It's well accepted by scientists that greenhouse gases trap heat in the Earth's atmosphere and tend to warm the planet. By increasing the levels of greenhouse gases in the atmosphere, human activities are strengthening Earth's natural greenhouse effect. The key greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries.
A warming trend of about 1°F has been recorded since the late 19th century. Warming has occurred in both the northern and southern hemispheres, and over the oceans. Confirmation of 20th-century global warming is further substantiated by melting glaciers, decreased snow cover in the northern hemisphere and even warming below ground.
Figuring out to what extent the human-induced accumulation of greenhouse gases since pre-industrial times is responsible for the global warming trend is not easy. This is because other factors, both natural and human, affect our planet's temperature. Scientific understanding of these other factors – most notably natural climatic variations, changes in the sun's energy, and the cooling effects of pollutant aerosols – remains incomplete.
In short, scientists think rising levels of greenhouse gases in the atmosphere are contributing to global warming, as would be expected; but to what extent is difficult to determine at the present time.
Scientists have identified that our health, agriculture, water resources, forests, wildlife and coastal areas are vulnerable to the changes that global warming may bring. But projecting what the exact impacts will be over the 21st century remains very difficult. This is especially true when one asks how a local region will be affected.
Scientists are more confident about their projections for large-scale areas (e.g., global temperature and precipitation change, average sea level rise) and less confident about the ones for small-scale areas (e.g., local temperature and precipitation changes, altered weather patterns, soil moisture changes). This is largely because the computer models used to forecast global climate change are still ill-equipped to simulate how things may change at smaller scales.
Some of the largest uncertainties are associated with events that pose the greatest risk to human societies. IPCC cautions, "Complex systems, such as the climate system, can respond in non-linear ways and produce surprises." There is the possibility that a warmer world could lead to more frequent and intense storms, including hurricanes. Preliminary evidence suggests that, once hurricanes do form, they will be stronger if the oceans are warmer due to global warming. However, the jury is still out whether or not hurricanes and other storms will become more frequent.
Like many pioneer fields of research, the current state of global warming science can't always provide definitive answers to our questions. There is certainty that human activities are rapidly adding greenhouse gases to the atmosphere, and that these gases tend to warm our planet. This is the basis for concern about global warming.
The fundamental scientific uncertainties are these: How much more warming will occur? How fast will this warming occur? And what are the potential adverse and beneficial effects? These uncertainties will be with us for some time, perhaps decades.
Global warming poses real risks. The exact nature of these risks remains uncertain. Ultimately, this is why we have to use our best judgement – guided by the current state of science – to determine what the most appropriate response to global warming should be.
Once, all climate changes occurred naturally. However, during the Industrial Revolution, we began altering our climate and environment through changing agricultural and industrial practices. Before the Industrial Revolution, human activity released very few gases into the atmosphere, but now through population growth, fossil fuel burning, and deforestation, we are affecting the mixture of gases in the atmosphere.
Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases:
Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned.
Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock.
Very powerful greenhouse gases that are not naturally occurring include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes.
Each greenhouse gas differs in its ability to absorb heat in the atmosphere. HFCs and PFCs are the most heat-absorbent. Methane traps over 21 times more heat per molecule than carbon dioxide, and nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide. Often, estimates of greenhouse gas emissions are presented in units of millions of metric tons of carbon equivalents (MMTCE), which weights each gas by its GWP value, or Global Warming Potential.
A sink is a reservoir that uptakes a chemical element or compound from another part of its cycle. For example, soil and trees tend to act as natural sinks for carbon – each year hundreds of billions of tons of carbon in the form of CO2 are absorbed by oceans, soils, and trees.
In the United States, approximately 6.6 tons (almost 15,000 pounds carbon equivalent) of greenhouse gases are emitted per person every 3.4% between 1990 and 1997. Most of these emissions, about 82%, are from burning fossil fuels to generate electricity and power our cars. The remaining emissions are from methane from wastes in our landfills, raising livestock, natural gas pipelines, and coal, as well as from industrial chemicals and other sources.
Emissions vary based on the country in which you live. The U.S. presently emits more greenhouse gases per person than any other country.
Emissions also vary based on the state you live in. Several factors can affect the emissions per person in a state, for example, the types of fuel used to generate electricity, population and vehicle miles traveled (people tend to drive longer distances in sparsely populated areas), and whether fossil fuels are extracted or processed within the state.
7.6 EFFECTS OF GLOBAL WARMING
7.6.1 EFFECTS ON BIOSPHERE
Climate change may have an effect on the carbon cycle in an interactive "feedback" process. A feedback exists where an initial process triggers changes in a second process that in turn influences the initial process. A positive feedback intensifies the original process, and a negative feedback reduces it. Models suggest that the interaction of the climate system and the carbon cycle is one where the feedback effect is positive.
Mountainous areas in Europe will face glacier retreat
In Latin America, changes in precipitation patterns and the disappearance of glaciers will significantly affect water availability for human consumption, agriculture, and energy production
In Polar regions, there will be reductions in glacier extent and the thickness of glaciers.
Global warming is projected to have a number of effects on the oceans. Ongoing effects include rising sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean surface, leading to increased temperature stratification. Other possible effects include large-scale changes in ocean circulation.
7.6.2 EFFECTS ON WEATHER
Increasing temperature is likely to lead to increasing precipitation but the effects on storms are less clear. Extratropical storms partly depend on the temperature gradient, which is predicted to weaken in the northern hemisphere as the polar region warms more than the rest of the hemisphere.
In the future, over most land areas, the frequency of warm spells or heat waves would very likely increase
7.6.3 EFFECTS ON AGRICULTURE
Climate change will impact agriculture and food production around the world due to: the effects of elevated CO2 in the atmosphere, higher temperatures, altered precipitation and transpiration regimes, increased frequency of extreme events, and modified weed, pest, and pathogen pressure. In general, low-latitude areas are at most risk of having decreased crop yields. With low to medium confidence, Schneider et al. (2007:787) concluded that for about a 1 to 3°C global mean temperature increase (by 2100, relative to the 1990-2000 average level) there would be productivity decreases for some cereals in low latitudes, and productivity increases in high latitudes.