Podcast
Questions and Answers
What is considered a key factor in determining the health of an environmental system?
What is considered a key factor in determining the health of an environmental system?
What happens to most species that have ever lived on Earth?
What happens to most species that have ever lived on Earth?
What is the estimated rate of species extinction due to human activity?
What is the estimated rate of species extinction due to human activity?
Which of the following categories is NOT one of the environmental indicators?
Which of the following categories is NOT one of the environmental indicators?
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By 2022, what is the estimated world human population?
By 2022, what is the estimated world human population?
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What has been a notable trend in world population growth since the 1960s?
What has been a notable trend in world population growth since the 1960s?
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Which food crops provide more than half of the total calories consumed by humans worldwide?
Which food crops provide more than half of the total calories consumed by humans worldwide?
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What does population growth imply about finite resources?
What does population growth imply about finite resources?
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What is one of the primary negative impacts of monoculture farming?
What is one of the primary negative impacts of monoculture farming?
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Which factor does NOT contribute to varying resource consumption across populations?
Which factor does NOT contribute to varying resource consumption across populations?
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Which greenhouse gas is primarily associated with human activities?
Which greenhouse gas is primarily associated with human activities?
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What major public health issue is linked to lead pollution?
What major public health issue is linked to lead pollution?
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What is the first step in the scientific method?
What is the first step in the scientific method?
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In environmental systems, what term describes the interaction between different systems?
In environmental systems, what term describes the interaction between different systems?
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Which of the following is a characteristic of closed systems?
Which of the following is a characteristic of closed systems?
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What does the term 'net flux' refer to?
What does the term 'net flux' refer to?
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What is a negative feedback loop?
What is a negative feedback loop?
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What is the primary source of greenhouse gases linked to human activity?
What is the primary source of greenhouse gases linked to human activity?
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Which of the following is NOT a common action that leads to air and water pollution?
Which of the following is NOT a common action that leads to air and water pollution?
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What environmental factor indicates the impact of human activity on ecosystems?
What environmental factor indicates the impact of human activity on ecosystems?
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What does the term 'sustainability' primarily refer to?
What does the term 'sustainability' primarily refer to?
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Which process involves making a testable and falsifiable statement?
Which process involves making a testable and falsifiable statement?
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Study Notes
Environmental Science Foundations
- Environmental science studies how human activities affect the environment, both positively and negatively.
- An environment encompasses all living organisms, geography, and climate in a specific area.
- Environmental systems are studied by analyzing interactions within isolated systems.
- Environmental indicators assess system health and identify problems.
- Indicators consider growth rates (increasing, decreasing), and geographic scales (global, regional).
- Six key environmental indicators: biological diversity, human population growth, food production, resource consumption, global temperature and atmospheric/greenhouse gas levels, and pollution levels.
Biological Diversity
- Earth has approximately 1.8 million identified species. A far greater, currently unknown number is probable.
- Species extinction is a natural process.
- About 99.9% of all species that have ever existed are extinct.
- The current "background" extinction rate is estimated at around 2 mammal extinctions per 10,000 species per 100 years.
- Human activities accelerate extinction rates significantly. The predicted current extinction rate due to human impact is estimated to be 40,000 species per year.
- This can lead to the collapse of ecosystems that humans depend on.
Human Population Growth
- Global human population was around 8 billion in 2022. Daily estimated births and deaths were 378,000 and 148,000 respectively.
- Global population growth was exponential before the 1960s and has since slowed.
- Slowing, yet continuing growth, is expected for approximately 50 more years.
- Population increase places greater demand on finite resources (energy, food, water, land).
- Unsustainable practices can significantly damage the environment.
Food Production
- Grains (wheat, corn, rice) provide over half of the calories consumed worldwide.
- Food production depends on factors like soil quality, climate, land availability, human labor, energy, and water.
- Farming methods affect environmental impact. Monoculture farming tends to degrade soil and lower yields.
- Polyculture practices can maintain soil quality and higher yields.
Resource Consumption
- Sustainability is essential for future generations.
- Current human activities often reduce environmental sustainability, impacting both humans and ecosystems.
- Activities that negatively impact the environment can sometimes benefit human quality of life.
- Resource consumption varies by factors such as location, economy, country, and lifestyle, thus impacting the environmental impact of different populations differently.
Global Temperature and Greenhouse Gases
- Earth's temperature is regulated by several factors including solar radiation, absorbed heat, ice cover, and greenhouse gasses.
- Greenhouse gases, such as carbon dioxide and methane, occur in both natural and human-influenced processes. Human-caused increases are primarily due to fossil fuel combustion and deforestation.
- Scientific consensus recognizes human activities as responsible for the rising levels of greenhouse gasses.
Air and Water Pollution
- Pollutants like lead can harm human health (particularly developing brains) and the environment.
- Lead is often released into the environment via burning coal and oil, unleaded gasoline (until policies in the 1970s), lead-based paints (common in homes before 1960s), and refining ores.
- Lead contamination in water, specifically in older plumbing, persists in some communities.
Scientific Method
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The scientific method involves observing the natural world without interference, generating testable and falsifiable hypotheses, determining the preliminary truthfulness of these hypotheses based on existing knowledge, and testing the hypotheses via experiments.
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Experiments must sufficiently differentiate between control and experimental groups, and define cause-and-effect relationships. Correlation is not causation.
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Experiments need large enough samples, and should demonstrate clearly measurable causes and effects.
Environmental Systems
- Earth's systems are interconnected, with actions in one area triggering reactions in others.
- System definitions are dependent on the perspective of the observer.
- The study of how systems interact with each other and themselves is called system dynamics.
Matter and Energy Exchange
- All environmental systems involve the exchange of matter and energy.
- Key materials include water, fuel (coal, gas, oil), chemicals, and gases (like oxygen). The ultimate energy source is from the sun.
Open and Closed Systems
- Open systems have inputs and outputs. Closed systems do not.
- Earth is an essentially closed system for matter(excluding occasional meteorites), but an open system for energy (solar radiation).
- The ocean is an open system for both matter (input/output from rivers) and energy (input from solar radiation).
Human Component in Environmental Systems
- Many fields (economics, social structures, law, policy, advocacy) profoundly affect the environment. Human activities shape environmental outcomes.
System Analysis
- System analysis involves identifying a system ("pool"), inputs, outputs, and flux (the amount of a variable over time).
- Net flux = Inputs -Outputs
- Steady-state occurs when inputs and outputs are equal (flux is zero). Examples such as water evaporation and precipitation in the atmosphere.
- Studying the ways matter and energy flow within environmental systems are critical to understanding them.
Feedbacks
- Feedback mechanisms control how systems respond to events or behaviors.
- Negative feedback loops attempt to return a system to a stable state, such as constantly maintaining a specific variable to its original value.
- Positive feedback loops drive systems away from a stable state.
- Unregulated feedback loops can lead to a decline away from a set point.
Regulating Population Systems
- Population size is determined by the balance of immigrants/births and deaths/emigration rates. The differences between these is known as "flows".
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Description
Test your understanding of the fundamental concepts in environmental science, focusing on how human actions influence ecosystems. Explore key indicators of environmental health, biological diversity, and the various factors affecting our planet's systems.
