Introduction to Environmental Science & the Scientific Method
What is environmental science?
"the interdisciplinary study of humanity’s relationship with other organisms and the non-living physical environment"
interdisciplinary because it
biology (ecology), geology, chemistry, physics
applied sciences: geography, agriculture, engineering
social sciences: economics, cultural anthropology, policy, politics, ethics, sociology
- uses & combines info from many disciplines
- natural sciences:
What environmental science is not
we need to differentiate between
- "science" aspect is emphasized
- "studying", becoming aware of current environmental issues, environmental ethics, environmentalism
Why is environmental science important?
Human domination of earth's ecosystems (from Vitousek et al., 1998. Science: 277: 494-499)
" to ! of land surface has been transformed by human action
atmospheric CO2 concentration has by ~30% since beginning of Industrial Revolution
more atmospheric nitrogen is fixed by humanity than all natural terrestrial sources combined
> ! of accessible freshwater is put to use by humanity
1/4 of bird species that ever lived on earth have been driven to extinction
2/3 of major marine fisheries are fully exploited, overexploited or depleted
Human population issues
Challenges and complexity
most experts believe environmental sustainability is not currently being achieved because
- "the ability of the environment to function indefinitely without going into a decline from the stresses imposed by human society on natural systems that maintain life"
- enables humanity’s present needs to be met without endangering the welfare of future generations
- applies at many levels
- individual, community, regional, national, global
- non-renewable resources (i.e., fossil fuels) are being used as if supplies were unlimited
- renewable resources (i.e., fresh water) are being used faster than they can be replenished naturally
- pollutants & toxins are being released into environment as if environment’s capacity to absorb them was unlimited
- human numbers continue to grow despite earth’s finite ability to support us
Human population issues
human population surpassed 6 billion in 1999
- placing unsustainable stresses on the environment
- consuming more food and water
- using more energy and raw materials
- producing more waste and pollution
- World Bank estimates that 1.3 billion people live in poverty
- unable to meet their basic needs for food, shelter, clothing
Challenges and complexity
issues may seem simple
Solutions - challenging & complex because of
- why don’t we just stop over-consumption, population growth and pollution?
- multifaceted interactions between ecological, social, cultural and economic factors
- inadequate scientific understanding of how
- the dynamic environment works
- how different human choices affect the environment
Some Current "hot" environmental issues
Declining bird populations
Some Current "Hot" Environmental Issues
chemicals that may interfere with actions of hormones
appear to alter reproductive development in both genders in many species
- chemical messengers in organisms
- regulate growth, reproduction, other activities
appear to alter reproductive development in both genders in many species cont
- >50% drop in sperm count from 1940-1990 in men (60 studies, 15,000 men, many nations)
- juvenile alligator density in Lake Apopka (FL) declined 10 fold in 14 years following chemical spill
many widely used chemicals fall into this category
US EPA plans to test thousands of chemicals for their potential to disrupt endocrine system
- river otters exposed to synthetic chemical pollutants were found to have abnormally small penises
- female seagulls in southern CA exhibited behavioral aberrations
- they paired with other females during mating season instead of paring with males
- results will help determine exposure levels, effects, limits
several have been fished to commercial extinction
Georges Bank closed in 1994
- = fish are harvested faster than they can replace themselves
- increased world demand
- high-tech methods increase catches
Grand Banks cod fishery (off Newfoundland) closed in 1990s
Peruvian anchovy fishery collapsed in 1970s
- 16,500 sq km area off New England in North Atlantic
- once one of world’s richest fishing grounds
- national level
- 1997 Magnuson Fishery Conservation & Management Act
- requires National Marine Fisheries Service and 8 regional councils to devise quotas and other strategies to help fisheries recover
- international level
- 1995 UN Fish Stocks Agreement
- first international treaty to regulate marine fishing
- Declining bird populations
- population declines seen across North America over past 2 decades
- particularly among songbirds of forests, shrub lands, grasslands
- many songbirds are tropical migrants
- winter in Central America, South America, Caribbean
- summer, migrate to North America to breed
- changing environments in both habitats
- burning of tropical rainforests for cropland
- fragmentation of temperate forest for development
- Ozone depletion
- evidenced as a large ozone "hole" over Antarctica
- "hole" is area where ozone concentration is lowest of any place in the world
- occur in layer of atmosphere called stratosphere
- layer between 10-45km above earth
- caused by chlorofluorocarbons (CFCs)
- previously widely used as cooling agents, still used some
- now banned or under phase out by most countries
- but existing CFCs can survive in atmosphere for 120+ years
caused by "greenhouse" gases
chief among these gases is carbon dioxide
- allow solar radiation to pass through to earth
- don’t allow heat to radiate into space
could cause increase in mean temperature (to levels higher than in past 100,000 years)
- CO2 levels have dramatically increased over past 2 centuries due mainly to
- burning of fossil fuels
- clearing & burning of forests
The Scientific Method
Extra! Extra! Read All About It...
- "Asteroid Eros Yields Secrets From Time Before Earth Was Born"
- "Discovery of Armored Viruses May Inspire New Designs for Nanotechnology"
- "Mechanism Found Behind Drug-Free Acceptance of Transplants"
- "Combination of Radiation and Hormone Suppression Therapy Shown to Effectively Treat Early-Stage Prostate Cancer"
- "UF Technique Detects Tiny, Potentially Harmful Airborne Particles"
- "Research Measures Migraine’s Impact on ‘Typical’ Sufferer, Links Migraine and Depression"
- "Stress Could Increase Risk of Heart Disease in Women"
- "Out of Time: Researchers Recreate 1665 Clock Experiment to Gain Insight Into Modern Synchronized Oscillators"
all of the above are headlines from science stories posted in a single day (9/25/00) on just one science news web site (ScienceDaily.com)
everyday we see or hear in the popular media reports of latest science research findings and how they impact our lives
According to a 1999 survey by the National Science Foundation (NSF)
Americans have great confidence in science
only ~21% were able to explain what it means to study something scientifically
only ~33% knew how an experiment was conducted
How can we demystify the process of science?
gain an understanding of the basic elements of the process of science
- but little understanding of the process underlying scientific research
- A process
- used to solve problems or develop an understanding of nature
- that involves testing possible answers.
- of gaining information about the world
- by forming possible solutions to questions, followed by rigorous testing
- to determine if the proposed solutions are valid.
- Specific causes for observed events.
- Causes can be identified.
- General rules can describe observations.
- Repeated events have same cause.
- Perceptions are not individualistic.
- Fundamental rules of nature are universal.
- Scientists pose and test hypotheses to answer questions about nature
- the process of science can be viewed as multi-step process
experiments - consist of
planned procedure to test hypothesis
analyze and interpret data
determine if data support hypothesis: accept, reject or modify hypothesis
carry out additional testing
share data with other scientists
if predictions are confirmed by scientific community, idea may become a theory
Results must be published for peers to be able to examine and criticize.
- senses, or extension of senses, are used to observe and/or record an event.
- can come from others or results of earlier tests
- resulting in the raising of a question
- about unclear aspects of the observations: how? why? when?
- leads to the development of an hypothesis
- are tentative explanations of a phenomenon phrased in such a way as to be testable
- logical statement that potentially explains an event, or answers a question.
- a good hypothesis will take into account all known facts, and will be as simple as possible. (Must be testable)
- with observations and hypotheses in mind, scientists develop tests (experiments)
- used to test hypothesis.
- to determine if predictions are supported (fail to falsify) or falsified
- have certain important components
- Controlled: Separate variables and divide experiment into experimental and control groups.
- Repeatability—Experiment is repeated to eliminate unconscious bias.
Development of Theories and Laws
- widely accepted, plausible generalization about fundamental scientific concepts that explain why things happen.
- Scientific vs. Vague Theory
- uniform or constant fact of nature that describes what happens in nature.
Limitations of Science
- Scientists struggle with the same moral and ethical questions as other people.
- Important to differentiate between data collected during an investigation, and scientists’ opinions of that data and its meaning.
- Some scientific knowledge can be used to support both valid and invalid conclusions.
- Science cannot shed light on all issues.
- It is very easy to confuse hypotheses with fact.
The Process of Science
- the process of science will not "prove" a hypothesis true
- results are used as evidence to support or falsify the hypothesis and usually become new observations in another cycle of investigation