#AP Environmental Science: The Ultimate Study Guide 📚

Welcome! This guide is designed to help you ace your AP Environmental Science exam. Let's dive in!

#🌍 Context: Human Impact on the Global Stage

This unit explores how human actions affect the environment on a global scale. We'll examine both the negative impacts and the positive steps we can take toward sustainability. Understanding these complex interactions is key to developing solutions for a healthier planet. Let's get started!

#☀️ Stratospheric Ozone Depletion

#Atmospheric Layers

• Troposphere: The layer closest to Earth, containing the air we breathe, greenhouse gases, and weather. ☁️
• Stratosphere: The layer above the troposphere, where the ozone (O3) layer is located. This layer is crucial for absorbing harmful UV radiation.

#The Ozone Layer

• The ozone layer is vital for life on Earth because it absorbs harmful UV radiation from the sun.

• Ozone (O3) molecules break down and reform continuously when hit by UV rays: O3 → O2 + O, then O2 + O → O3. ### Human Impact: CFCs

• Chlorofluorocarbons (CFCs), used in propellants, are very stable and can reach the stratosphere.

• In the stratosphere, UV radiation breaks down CFCs, releasing chlorine (Cl).

• Chlorine reacts with oxygen (O) atoms, preventing them from reforming ozone (O3), thus depleting the ozone layer. 💡

Image from Pixabay

#🤝 Reducing Ozone Depletion

• The Montreal Protocol (1989): An international agreement that phased out ozone-depleting chemicals like CFCs.

• The Montreal Protocol is considered a major success in international environmental cooperation.

• It will take around 100 years to fully see the effects of reducing CFC use due to their long lifespan in the atmosphere.

#🌡️ Global Climate Change

#The Greenhouse Effect

• The greenhouse effect is a natural process where heat from solar energy is trapped near Earth's surface by certain gases.
• Greenhouse gases have a higher thermal retention property, meaning they can hold heat longer.

#Primary Greenhouse Gases

• Key Greenhouse Gases: Carbon Dioxide (CO2), Methane (CH4), Water Vapor (H2O), Nitrous Oxide (N2O), and Chlorofluorocarbons (CFCs).
• Human activities increase the concentration of these gases in the troposphere, leading to increased global average temperatures.

#Global Warming Potential (GWP)

• GWP measures how much heat a gas can trap compared to CO2. * Different gases have different GWPs, as shown in the chart below:

#🌊 Ocean Acidification

#The Chemistry

• Increased atmospheric CO2 leads to more CO2 being absorbed by the oceans.
• When CO2 dissolves in seawater, it forms carbonic acid (H2CO3), which then dissociates into bicarbonate (HCO3-) and hydrogen ions (H+).
• The increase in H+ ions decreases the pH of the ocean, making it more acidic.

$$CO_2 (aq) + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons HCO_3^- + H^+ \rightleftharpoons CO_3^{2-} + 2H^+$$

#Impacts on Marine Life

• Ocean acidification makes it difficult for organisms like corals, algae, and shellfish to build their calcified shells. 🐌
• This impacts the entire food chain, especially organisms like pteropods, which are a major food source.

Image from Wikipedia

#🐒 Human Impacts on Biodiversity

#Biodiversity Decline

• Human actions are causing drastic changes that impact plant and animal populations.
• Both the total number of organisms and the number of species are declining.
• The IUCN estimates that around 25% of all species are currently threatened with extinction.
• This is considered one of the largest mass extinction events in Earth's history. 🐉

#Species Vulnerability

• Specialist and K-selected organisms are more susceptible to extinction.
• Generalist and r-selected organisms are more likely to adapt.

#HIPPCO: The Major Drivers of Species Decline

• Habitat destruction
• Invasive species
• Population growth
• Pollution
• Climate change
• Over-exploitation

Image from Wikipedia

Biodiversity loss and its drivers are a frequent topic on the AP exam. Make sure to understand HIPPCO and the different types of species.

#📜 Laws and Treaties

#Key Environmental Legislation

• 1973 - The Endangered Species Act (USA): Protects endangered and threatened species and their habitats.
• 1987 - The Montreal Protocol: International agreement to phase out ozone-depleting chemicals.
• 1992 - The Kyoto Protocol: International agreement to reduce greenhouse gas emissions.
• 1996 - National Invasive Species Act (NISA) (USA): Prevents the introduction of invasive species through ballast water.
• 2016 - The Paris Agreement: International agreement to mitigate greenhouse gas emissions (though the U.S. has withdrawn).

#🎯 Final Exam Focus

#High-Priority Topics

• Climate Change: Understand the greenhouse effect, major greenhouse gases, and their sources.
• Ozone Depletion: Know the causes, effects, and the success of the Montreal Protocol.
• Ocean Acidification: Understand the chemistry and its impacts on marine life.
• Biodiversity Loss: Be familiar with HIPPCO and the characteristics of vulnerable species.
• Environmental Laws and Treaties: Know the main goals and impacts of key legislation.

#Common Question Types

• Multiple Choice: Expect questions on the causes and effects of environmental problems, as well as the effectiveness of different solutions.
• Free Response Questions (FRQs): Be prepared to analyze data, propose solutions, and discuss the social and economic impacts of environmental issues.

#Last-Minute Tips

• Time Management: Don't spend too long on any one question. Move on and come back if you have time.
• Read Carefully: Pay close attention to the wording of each question.
• Use Specific Examples: When answering FRQs, use specific examples to support your points.
• Stay Calm: Take deep breaths and trust your preparation. You've got this!

#📝 Practice Questions

Practice Question

#Multiple Choice Questions

1. Which of the following is NOT a major greenhouse gas? (A) Carbon Dioxide (B) Methane (C) Nitrogen (D) Nitrous Oxide

2. The Montreal Protocol is an international agreement that aims to: (A) Reduce greenhouse gas emissions (B) Phase out ozone-depleting chemicals (C) Protect endangered species (D) Prevent the introduction of invasive species

3. Which of the following best describes the process of ocean acidification? (A) Increased absorption of nitrogen by the ocean (B) Increased absorption of carbon dioxide by the ocean (C) Decreased absorption of carbon dioxide by the ocean (D) Increased absorption of methane by the ocean

#Free Response Question

Scenario: A coastal community is experiencing a decline in shellfish populations. Scientists have determined that ocean acidification is a contributing factor.

(a) Explain the chemical process that leads to ocean acidification. (3 points) (b) Describe TWO specific impacts of ocean acidification on marine ecosystems. (4 points) (c) Propose ONE realistic strategy that could be implemented to reduce the effects of ocean acidification in this community. (3 points)

Scoring Breakdown:

(a)

• (1 point) Explanation of increased CO2 absorption by the ocean.
• (1 point) Explanation of the formation of carbonic acid (H2CO3).
• (1 point) Explanation of the increase in H+ ions and decrease in pH.

(b)

• (2 points) One point for each impact described (e.g., difficulty in shell formation, disruption of the food chain, coral bleaching).
• (2 points) One point for each impact described (e.g., difficulty in shell formation, disruption of the food chain, coral bleaching).

(c)

• (1 point) Proposal of a realistic strategy (e.g., reducing local carbon emissions, restoring coastal habitats).
• (2 points) Explanation of how the strategy would help reduce the effects of ocean acidification.

Good luck on your exam! You've got this! 💪