Environmental Science Semester Review

Objectives Define environmental science and compare environmental science with ecology and environmentalism. List five major fields of study that contribute to environmental science. Distinguish between a renewable resource and a non-renewable resource. Explain the concept of sustainability and why it is a goal in environmental science. Explain the concept of an Ecological Footprint

Environmental Science Environmental science is the study of: How the natural world works How the environment affects humans and vice versa We need to understand our interactions with the environment To creatively solve environmental problems NYC Today and 400 yrs ago

The Nature of Environmental Science Environment  impacts  Humans Its applied goal: solving environmental problems Solutions are applications of science An interdisciplinary field Natural sciences: examines the natural world Environmental science programs Social sciences: examines values and human behavior Environmental studies programs

Environmental science Can help us avoid mistakes made by past civilizations Human survival depends on how we interact with our environment. Our impacts are now global. Many great civilizations have fallen after depleting their resources. The lesson of Easter Island: people annihilated their culture by destroying their environment. Can we act more wisely to conserve our resources?

Environmental Science is not Environmentalism Pursues knowledge about the environment and our interactions with it Scientists try to remain objective and free from bias Environmentalism A social movement Tries to protect the natural world from human-caused changes

Goals of Environment Science To understand and solve environmental problems Ecosystem functions Air Pollution Water Pollution Toxic Chemicals Climate Change Resource usage

Ecology is the Foundation of Environmental Science Ecology: the study of how living organisms interact with each other and their non-living environment

Fields of Study that Contribute to Environmental Science Biology: the study of living organisms Chemistry: the study chemicals and their interactions Physics: the study of matter and energy Earth Science: the study of earth’s nonliving systems Social Sciences: the study of human populations

We Rely on Natural Resources Natural resources = substances and energy sources needed for survival Renewable natural resources: can be replenished Perpetually renewed: sunlight, wind, wave energy Renew themselves over short periods: timber, water, soil These can be destroyed Nonrenewable natural resources: unavailable after depletion Oil, coal, minerals

Natural Resources Renewable resources like sunlight cannot be depleted. Nonrenewable resources like oil CAN be depleted. Resources like timber and clean water are renewable only if we do not overuse them. Figure 1.1

Our “Ecological Footprint” Affluence increases consumption Ecological footprint: the environmental impact of a person or population The area of biologically productive land + water To supply raw resources and dispose/recycle waste People in rich nations have much larger ecological footprints If everyone consumed the amount of resources the U.S. does, we would need 4.5 Earths!

Overshoot Humans have surpassed the Earth’s capacity to support us We are using renewable resources 30% faster than they are being replenished

Population & Consumption Population growth amplifies all human impacts The growth rate has slowed, but we still add more than 200,000 people to the planet each day Resource consumption has risen faster than population Life has become more pleasant Rising consumption also amplifies our demands on the environment The 20 wealthiest nations have 55 times the income of the 20 poorest nations Three times the gap that existed 40 years ago

Ecological Footprints are not Equal Not everyone benefits equally from rising affluence The ecological footprints of countries vary greatly The U.S. footprint is much greater than the world’s average In the U.S. the richest 1% Have 25% of all income

Sustainability is the Goal! Condition in which human needs are met without harming future generations. We are not living sustainably today. What needs to change?

Sustainability and the Future of our World Sustainability: we must live within our planet’s means So the Earth and its resources can sustain us and all life for the future Sustainability involves conserving resources Developing long-term solutions Keeping fully functioning ecosystems Natural capital: Earth’s total wealth of resources We are withdrawing it faster that it’s being replenished We must live off Earth’s natural interest (replenishable resources), not its natural capital

Sustainable Solutions Sustainable development using resources to satisfy current needs without compromising future availability of resources Sustainability involves Renewable energy sources Soil conservation, high-efficiency irrigation, organic agriculture Pollution reduction Habitat and species protection Recycling Fighting global climate change Humanity’s challenge is to develop solutions that further our quality of life while protecting and restoring the environment.

Will we develop in a sustainable way? This is the single most important question we face.

Objectives Understand the Nature of Science Understand how scientific inquiry and technological design, including mathematical analysis, can be used to pose questions, seek answers, and develop solutions. Describe and Apply the Scientific Process Describe how humanity altered the environmental Hunter-gatherers Agricultural revolution Industrial revolution

The Nature of Science Science: a systematic process for learning about the world and testing our understanding of it The accumulated body of knowledge arising from the dynamic process of observation, testing, and discovery Civilization depends on science and technology Science tries to understand the world and steer a safe course Science is essential to sort fact from fiction Develop solutions to the problems we face It must be accessible and understandable to the public

Science Asks and Answers Questions It is an incremental approach to the truth Scientists do not simply accept conventional wisdom They judge ideas by the strength of their evidence Observational (descriptive) science: information is gathered about organisms, systems, processes, etc. Cannot be manipulated by experiments Phenomena are observed and measured Used in astronomy, paleontology, taxonomy, genomics Hypothesis-driven science: targeted research Experiments test hypotheses using the scientific method

The Scientific Method: A Traditional Approach Science tests ideas Scientists in different fields approach problems differently Assumptions: The universe works according to unchanging natural laws Events arise from causes, and cause other events We use senses and reason to understand natural processes

Applications of Science Policy decisions and management practices are applications of science. Prescribed burning, used to restore forest ecosystems altered by human suppression of fire. Figure 1.8a

Applications of Science Technology is another application of science. Energy-efficient methanol-powered fuel cell car from DaimlerChrysler Figure 1.8b

Scientific Method: Assumptions Fixed natural laws govern how the universe works All events arise from causes, and cause other events We can use our senses and reason to detect and describe nature’s laws

Scientific Method A step-by-step method for testing ideas with observations. Scientists use educated guesses called hypotheses to generate predictions hypotheses are tested experimentally. Results may reject or support a hypothesis. Results never prove a hypothesis, but only lend support to it by failing to reject it. Figure 1.9

Scientific Process Peer review, publication, and debate are parts of the larger scientific process. Figure 1.11

Hypothesis, Theory, and Paradigm Hypothesis = an educated guess, to be tested Theory = a well-tested and widely accepted explanation, validated by much previous research Paradigm = a dominant view. May shift if new results show old results or assumptions to be wrong

Experiments Test the Validity of a Hypothesis Variable: a condition that can change Independent variable: is manipulated Dependent variable: is measured and depends on the independent variable Controlled experiment: the effects of all variables are controlled Except the independent variable whose effect is being tested Control: an un-manipulated point of comparison Quantitative data: uses numbers Qualitative data: does not use numbers

Hypotheses are Tested in Different Ways Manipulative experiments Yield the strongest evidence Reveals causal relationships Lots of things can’t be manipulated Natural tests Results are not neat and clean Show real-world complexity Answers aren’t black and white

Human Impact Over Earth’s History Wherever humans have hunted, grown food, or settled we have changed the environment. How have those changes impacted the environment over human history?

Hunter-Gatherers Most of human history Obtained food by moving around collecting plants and hunting wild animals. Affected the environment: Set fires to drive game during hunting Spread plant species as they moved from place to place May have led to the disappearance of many large mammal species such as ground sloths, giant bison, mastodons, cave bears, and saber-tooth cats

Agricultural Revolution Plants and animals were domesticated and population grew 10,000 years ago Life got easier Settlements began forming Impact on environment grew Habitat destroyed Artificial selection of domesticated crops Farmland replaced forest Agricultural Revolution

Industrial Revolution There was a shift to fossil fuels as an energy source Mid-1700s Life got easier Advances in technology Healthcare and sanitation improved People lived longer People moved to cities away from farms Increased environmental impact.

Thomas Malthus and human population Population growth must be controlled, or it will outstrip food production. Starvation, war, disease Neo-Malthusians Population growth has disastrous effects. Paul and Anne Ehrlich, The Population Bomb (1968) Agricultural advances have only postponed crises.

Human Population Levels Throughout History

Loss of Biodiversity Biodiversity: the number and variety of species that live in an area Why is loss of biodiversity a bad thing? Higher biodiversity = healthier ecosystem Organisms are considered a natural resource

We face challenges in biodiversity Biodiversity: the cumulative number and diversity of living things Human actions have driven many species extinct Biodiversity is declining dramatically We are setting in motion a mass extinction event Biodiversity loss may be our biggest problem; once a species is extinct, it is gone forever