Chapters 1 - 3Chapters 1 - 3Basic Issues in Environmental Basic Issues in Environmental

ScienceScience

Human activity is beginning to affect Human activity is beginning to affect environment globally.environment globally.

1.1. Population growth = underlying causePopulation growth = underlying cause

2.2. IndustrializationIndustrialization

3. 3. Unsustainable practicesUnsustainable practices

Value of Environment?Value of Environment? UtilitarianUtilitarian

-- Ecological justificationEcological justification

-- AestheticAesthetic

-- MoralMoral

--

Precautionary PriciplePrecautionary Priciple

If there is a global threat of serious or If there is a global threat of serious or maybe irreversible environmental damage,maybe irreversible environmental damage,

we should not wait till all the scientific we should not wait till all the scientific evidence is in before taking steps to prevent evidence is in before taking steps to prevent the potential problem from occuring.the potential problem from occuring.

Value of Coral Reefs?Value of Coral Reefs?

Scientific Knowledge is Critical!Scientific Knowledge is Critical!

Controlled ExperimentsControlled ExperimentsIndependent variableIndependent variableDependent variableDependent variableControlControl

DataDataquantitativequantitative

qualitative qualitative

Environmental science in…Environmental science in…

The mediaThe media

PoliticsPolitics

Decision makingDecision making

Environmental Systems ChangeEnvironmental Systems Change

Amboseli National Park (case study)Amboseli National Park (case study)(What happened and whose fault?)(What happened and whose fault?)

SystemsSystems Open Open

ClosedClosed

System responses:System responses:a. a. Negative feedbackNegative feedback – most common – most common

(an increase in some (an increase in some

output will lead to an eventual output will lead to an eventual decrease in that output - stabilizes)decrease in that output - stabilizes)

b. b. Positive feedbackPositive feedback – output increase – output increase leads to more output increase leads to more output increase (problem intensifies)(problem intensifies)

Global Climate ChangeGlobal Climate ChangeWhich feedback system will dominate?Which feedback system will dominate?

+ Positive?+ Positive?

- Negative?- Negative?

System Changes and EquilibriumSystem Changes and Equilibrium

DepletionDepletion: output larger than input: output larger than input

Examples: Examples:

GrowthGrowth: output smaller than input: output smaller than input

Examples:Examples: bans on harvesting:bans on harvesting:

Steady StateSteady State: output = input: output = input

Examples:Examples: sustainable practicessustainable practices

Natural and Human Impacts on Natural and Human Impacts on SystemsSystems

Most natural disturbances tend to be in Most natural disturbances tend to be in balance and life has often co-evolved with balance and life has often co-evolved with them.them.

Many important!Many important!

Examples:Examples:

Delays in ResponseDelays in Response Responses to change not always immediateResponses to change not always immediate May be non-linear, effects not seen for a May be non-linear, effects not seen for a

while while Examples:Examples:

Once seen, may be difficult to correctOnce seen, may be difficult to correct

Residence TimesResidence Times Example: PollutantsExample: Pollutants Quick flow through (short A.R.T.) affects system Quick flow through (short A.R.T.) affects system

quickly but recovers quickly if problem remediedquickly but recovers quickly if problem remedied

Slow flow through (long A.R.T.) takes a Slow flow through (long A.R.T.) takes a longer time to show effects but longer to longer time to show effects but longer to recover even after problem remedied.recover even after problem remedied.

Environmental UnityEnvironmental Unity

Everything affects everything else!Everything affects everything else! Changes in one part of system has multiple Changes in one part of system has multiple

effects in that system and other systems.effects in that system and other systems.

UniformitarianismUniformitarianism Processes happening in the present were Processes happening in the present were

also happening in the pastalso happening in the past– The magnitude and frequency of events may The magnitude and frequency of events may

vary over time, but the processes are the samevary over time, but the processes are the same

GaiaGaia Earth and all living things are part of a Earth and all living things are part of a

single systemsingle system Life greatly affects the system and regulates Life greatly affects the system and regulates

the planetary environment to help sustain the planetary environment to help sustain lifelife