Principles of Environmental Science
CH1. Understanding Our Environment
1.1. What is Environmental Science?
Environmental Science is the use of scientific approaches to understand the complex system
in which we live. We study our environment and our place in it. Other characteristics:
1) Integrative; ES involves both natural and human worlds. It draws on a wide range of
disciplines and skills.
2) Global; we have much interdependencies throughout the world.
3) ES helps us understand our remarkable planet; the value of ecological services is
almost incalculable.
Methods in ES
- Observation; the first step is a careful, detailed observation and evaluation
- Scientific method; an orderly approach to asking questions, collecting observations
and interpreting those observations.
- Quantitative reasoning; understanding how to compare numbers and interpret
graphs, to perceive what they show about problems of matter.
- Uncertainty; science is based on observation and testable hypotheses but we know
there are limits to our knowledge.
- Critical and analytical thinking; the practice of stepping back to examine what you
think and why you think it.
1.2 Major themes in ES
Environmental quality
- Climate change; in the past 200 years, concentrations of CO2 in the atmosphere have
increased nearly 50%. If the current trend will continue, global mean temperatures will
probably rise by 2-6 degrees Celsius by 2100 compared to 1990 temperatures.
- Clean water; at least 1.1 billion people lack access to save drinking water, and twice
that many don’t have adequate sanitation.
- Air Quality; Millions of early deaths and many more illnesses are triggered by air
pollution each year.
Human population and well-being
- Population growth; trends project a population between 8 and 10 billion by 2050. But
demographers report a transition to slower growth rates in most countries. Since 1960
the average numbe of children born per woman worldwide has decreased from 5 to
2.45.
- Hunger and food; over the past century, global food production has increased faster
than human population growth. We now produce about half again as much food as we
need to survive, and consumption of protein has increased worldwide. But hunger
remains a chronic problem worldwide because food resources are unevenly
distributed.
- Information and education; improved access to education is helping to release many
of the world’s population from cycles of poverty and vulnerability.
,Natural Resources
- Biodiversity loss; habitat destruction, overexploitation, pollution, and the introduction
of exotic organisms are eliminating species as quickly as the great extinction that
marked the end of the age of dinosaurs. Over the past century more than 800 specis
have disappeared and at least 10,000 species are now considered threatened.
- Conservation of forest and nature preserves; while exploitation continues, the rate of
deforestation has slowed in many regions.
- Marine resources; despite the ongoing overexploitation, many countries are beginning
to acknowledge the problems of the depletion of the oceans.
- Energy resources; Fossil fuels presently provide around 80% of the energy used in
industrialized countries.
1.3 Human dimensions of environmental science
Throughput; the amount of resources we use and dispose of.
Ecosystem services; refers to services or resources provided by environmental systems:
- Provisioning of resources: fuel
- Supporting services: water purification, production of food and atmospheric oxygen by
plants, decomposition of waste by bacteria and fungi.
- Regulating: maintenance of temperatures suitable for life by the earth’s atmosphere and
carbon capture by green plants.
- Cultural services: diverse range of recreation, aesthetic and nonmaterial benefits.
Sustainability is a search for ecological stability and human progress that can last over the
long term.
Sustainable development: meeting the needs of the present without compromising the ability
of future generations to meet their own needs. Addressing uneven distribution of resources is
one of the first tasks of sustainable development.
In both rich and poor countries, native, or indigenous people are generally the least powerful,
most neglected groups. Of the world’s nearly 6000 recognized cultures, 5000 are indigenous,
and these account for only 10% of the total world population.
The goals of sustainable development in agenda 21 of the UN Earth Summit in 1992
1) Combating poverty
2) Reducing resource consumption
3) Reduce population growth by better family planning
4) Health care improvement
5) Sustainable cities
6) Environmental policy to guide decision making
7) Protection of the atmosphere
8) Combating deforestation and protecting biodiversity
9) Combating desertification and drought
10) Agricultural and rural development
1.4 Science helps us understand our world
Science is a process for producing knowledge based on observations. The benefit of scientific
thinking is that it searches for testable evidence.
,Basic principles of science
1) Empiricism: we learn by careful observation of empirical phenomena
2) Uniformitarianism: basic patterns and processes are uniform across time and space.
3) Parsimonony: Ockham’s razor: when two plausible explanations are reasonable, the
simpler one is preferable.
4) Uncertainty: knowledge changes as new evidence appears, and explanations change
with new evidence.
5) Repeatability: you and other scientist should be able to replicate your findings.
6) Proof is elusive: we don’t expect science to provide absolute proof.
7) Testable questions: we form hypotheses to test theories.
Deductive reasoning: logical reasoning from general to specific.
Inductive reasoning: reasoning from many observations to produce a general rule.
Scientific theory: When an explanation has been supported by a large number of tests, and
when a majority of experts have reached a general consensus that it is a reliable description or
explanation.
Probability: a measure of how likely something is to occur. We consider a causal explanation
reliable if there is less than 5% probability that is happened by random chance.
Experimental Designs
- Natural experiment: you observe natural events and interpret a causal relationship
between the variables.
- Manipulative experiments: conditions are deliberately altered and all other variables
are held constant.
- Controlled study: compare a treatment (exposed) group and a control (unexposed)
group.
- Blind experiments: the researcher doesn’t know which group is treated until after the
data have been analysed.
- Double-blind experiments: neither the subject, nor the researcher knows who is in
the treatment group en who is in the control group.
Variables
- Dependent variable/ response variable: is affected by the independent variable (Y-
axis).
- Independent variable/explanatory variable: we hope they will explain differences
in a dependent variable.
Paradigm shifts: according to Kuhn, this occurs when a majority of scientist accept that the
old explanation no longer describes new observations very well.
Types of thinking
- Critical thinking: logical, orderly, analytical assessment of ideas, evidence, and
arguments.
- Analytical thinking: helps you break a problem down in its constituents’ parts
- Creative thinking: how might I approach this problem in new and inventive ways?
- Logical thinking: evaluates whether the structure of your argument makes sense
- Reflective thinking: what does it all mean?
Steps of critical thinking
1) Identify and evaluate premises and conclusions in an argument
, 2) Acknowledge and clarify uncertainties, vagueness, equivocation and contradictions.
3) Distinguish between facts and values
4) Recognize and assess assumptions
5) Distinguish source reliability or unreliability
6) Recognize and understand conceptual frameworks
1.6 Where do our ideas about the environment come from?
There are 3 stages:
1) The basis of Roosevelt’s and Pinchot’s policies was pragmatic utilitarian
conservation. The first principle of conservation is development and use of the natural
resources now existing on this continent for the benefit of the people who live here
now.
2) John Muir argued that nature deserves to exist for its own sake, regardless of its
usefulness to us. His outlook prioritized preservation because it emphasizes the
fundamental right of other organisms to exist and to pursue their own interests.
3) In 1962 Rachel Carson published Silent Spring to awaken the public to the threats of
pollution and toxic chemicals to humans as well as other species. The movement is
called modern environmentalism.
4) Environmental quality is tied to social progress on a global scale, its called global
environmentalism.
CH2 Environmental Systems: Matter, Energy, and Life
2.1 Systems describe interactions
System: a network of interdependent components and processes, with materials and energy
flowing from one component of the system to another. A simple system consists of
compartments (state variables), which store resources such as energy or matter, and the flows,
or the pathways, by which those resources move from one compartment to another.
Ecosystem: the complex assemblages of animals, plants, and their environment, through
which materials and energy move.
Types of systems
- Open systems: those that receive inputs form their surroundings and produce outputs
that leave the system.
- Closed system: exchanges no energy or matter with its surroundings.
- Throughput: the flow of energy and matter into, through, and out of a system.
- Equilibrium: when a system is in a stable balance.
- Dynamic equilibrium: variation around an average that remains stable over time.
- Thresholds: tipping points where rapid change suddenly occurs if you pass certain
limits.
Feedback loops
- Positive feedback loop: increase a process or component
- Negative feedback loop: diminishes a process or a component.
2.2 Elements of life
Matter: everything that takes up space and has mass.
