Chapter 1

Studying the State of our Earth

Environmental Science vs. Environmentalism

This is what the course may lead to • Social movement• Lobbying • Activism• Goals may include

– Protection of an area

– Prevention of pollution

– Educating others about an issue

This is what the course is about

• Observing environmental conditions

• Field testing• Hypothesizing the

relationship between variables

• Testing hypothesis• Environmental Studies• History of Human Activity

• We convert land from its natural state– Urbanization and Housing– Agricultural– Industrial

• We change the chemistry of our air, water and soil– Adding fertilizers– Generating Pollution

Humans Alter Natural Systems

Humans Alter Natural Systems

• Hunting practices– Extinction of Mammoths,

Mastodons, Giant Ground Sloths and Passenger Pigeons

• Technology Development of over Past 200 years– Electricity, running water, sewer

systems, public transit and internet connections.

Rate of Changes vs. Recovery

• Humans are changing environmental conditions at an ever increasing rate.

• Organisms must adapt, relocate or go extinct.

• The natural environmental systems that are being impacted do not have time to evolve.

• The impact of human activity is compounded by the size of our population.

Environmental Indicators of Stress

1. Loss of biodiversity

2. Declines in food production

3. Increasing global surface temperatures and CO2 levels.

4. Increasing Human population

5. Depletion of resources (both renewable and non-renewable)

Loss of Biodiversity1. Biological Diversity

– Genetic Diversity: organisms with high genetic diversity are better able to adapt to environmental change.

– Species Diversity: ecosystems with higher species diversity are more resilient to change. • Ideally the rate of speciation should equal

the background extinction rate– Ecosystem Diversity: a measure of the variety

and health of ecosystems and habitats in a given area

Declines in Food Production• Grain production is a standard global measurement of

productivity• Worldwide grain production has steadily increased since

1950 as a result of new technologies and innovations• At the same time, worldwide production of grain per

person (per capita) has leveled off.

• What causes declines in productivity?– Soil degradation– Extreme climate conditions (i.e. drought,

floods)– Crop disease– How we use our grain

• We use more grain to feed livestock than we use to feed ourselves. In terms of energy conversions, this is very inefficient.

Food Production- Continued

Average Global Surface Temperature and CO2 are increasing.

• Scientists have seen a correlation between CO2 levels and global temperature changes.

– Anthropogenic causes of atmospheric CO2 increase

– Combustion of fossil fuels

– Net loss of forests

– The rate of population growth has been slowing since the 1960’s

– The overall population will continue to grow for at least the next 50-100 years.

– Projections estimate that the population will reach between 9 &10 billion by the year 2050.

Increasing Human Population

Depletion of Resources

• Extraction of resources degrades the environment – Pollution from mining (acid

mine drainage)• Renewable resources like

timber from forests are being harvested faster than they are replenished.

Patterns of Resource Consumption

• Developed nations contain 20% of the human population however they consume the greatest percentage of resources.– Energy– Meat– Automobiles– Paper

Sustainable Practices

• Environmental systems must not be damaged beyond their ability to recover

• Renewable resources must not be depleted faster than they can regenerate

• Non-renewable resources must be used sparingly

Examples of Sustainable Practice• Iron is a non-renewable resource

– Our improved ability to extract it and convert it into steel has increased the demand for iron.

– We use it in tall buildings, automobiles, bicycles and tools.

• We have developed alternative building materials: carbon fibers

• We recycle the iron rather than extracting it from ore.

Defining Human Needs• Conveniences

– Electricity– Air conditioning– Lighting– Computers– Heating– Cars– Clothing

• Basic Needs–Clean air–Clean water–Food–Shelter–Connection

to living things

The Ecological Footprint

• Developed in 1995 by Professor William Rees and his graduate student Mathis Wackernagel– Designed to measure how much a person

consumes expressed in an area of land that is needed to produce the goods or services used.

– If our lifestyle demands more land than is available, then we are living unsustainably.

What is Your Ecological Footprint?• If everybody lived like the average U.S. citizen

we would need 5 Earth’s to meet our needs. (Average = 23.7 acres per person)

• Currently estimates have the human footprint at 14 billion hectares (125% of the planet’s resources.

• To be sustainable humans should have a footprint of about 11 billion hectares.

• In order to preserve land for other species our footprint needs to be even lower than 11 billion hectares.

Science is a Process• The Scientific Method

– Good science requires researchers to maintain multiple working hypotheses.

– A hypothesis is never confirmed or rejected by a single experiment

– Often it is easier to prove something wrong than it is to prove something true beyond any doubt. • This is a called a ‘null hypothesis’

Accuracy & Precision of Results• Scientists will replicate data in order to test

for reliability of results– The method used to collect the data should

provide accurate results– Each time an experiment is performed it

should yield similar results.

A Standard Curve• In order to be sure that your results are accurate

when testing for environmental pollutants a scientist should create a standard curve.– Known quantities of a given pollutant are tested. – If the results do not fall on the standard curve

then there is very little confidence in the results for the unknown samples.

Case Study- Scientific Method• Observations: Chlopyrifos (part of insecticides) may

have an effect on the central nervous system• Hypothesis: Chlorpyrifos causes neurological disorders

and negatively affect human health.• Null Hypothesis: Chlorpyrifos has no observable

negative effects on the central nervous system.• Experiment: Two groups (10 rats per group).

– Experimental group is fed small doses of chlorpyrifos (insecticide) during first 4 days of life

– Control group experiences same exact conditions except for the insecticide

• Results: rats exposed to chlorpyrifos had much lower levels of the brain enzyme choline acetyltransferase

Science and Progress• After multiple rounds of testing

researchers had confidence in their findings that insecticides that contain chlorpyrifos are harmful to human health

• The U.S. E.P.A. prohibited its use for residential applications and for certain agricultural applications.

Unique Challenges for Environmental Science

• Lack of baseline data– We do not have a ‘control Earth’ to compare to our

contemporary Earth.• Subjectivity

– It is often difficult to know which activities are most harmful to the environment. Many of our decisions must include value judgments.

• Interactions– Environmental systems are complex.– Human systems and Human behavior is complex.

• Human Well Being– Environmental justice: Who has the right to the limited

resources of the Earth. Who should make these decisions?