AP Environmental Science Units: Full List

If you're studying AP Environmental Science (APES), it's important to understand how the course is structured.

The College Board divides the course into nine distinct units, each focusing on a different environmental theme.

These units build a strong foundation of scientific knowledge, data analysis skills, and environmental problem-solving.

In this article, you’ll find a clear breakdown of each AP Environmental Science unit.

We’ll also explain the APES science practices and point you to revision resources that will help you prepare with confidence.

College Board AP Environmental Science Units

Here is a full list of the nine units covered in AP Environmental Science:

1. The Living World: Ecosystems

2. The Living World: Biodiversity

3. Populations

4. Earth Systems and Resources

5. Land and Water Use

6. Energy Resources and Consumption

7. Atmospheric Pollution

8. Aquatic and Terrestrial Pollution

9. Global Change

Unit 1: The Living World: Ecosystems

Discover the intricate web of life where every organism plays a role, and even decomposers are ecological VIPs.

You’ll learn how ecosystems function, including the flow of energy and cycling of matter. Key topics include:

• Terrestrial and aquatic biomes

• Biogeochemical cycles (carbon, nitrogen, phosphorus and hydrologic cycles)

• Primary productivity

• Trophic levels, energy flow and the 10% rule

• Food chains and food webs

Unit 2: The Living World: Biodiversity

Explore the dazzling variety of life on Earth—and why protecting it is key to a thriving, resilient planet.

This unit explores the importance of biodiversity to ecosystems. Key topics include:

• Ecosystem services

• Island biogeography

• Ecological tolerance and natural disruptions

• Adaptations

• Ecological succession

Unit 3: Populations

Unpack the story behind population booms and busts—and how they shape everything from ecosystems to economies.

You’ll investigate population dynamics and how populations interact with the environment. Key topics include:

• Generalist and specialist species

• Survivorship curves

• Carrying capacity and limiting factors

• Age structure diagrams and demographic transition

• Human population growth and resource use

Unit 4: Earth Systems and Resources

Uncover the powerful natural forces—like volcanoes, weather patterns, and ocean currents—that shape life on Earth every day.

This unit covers Earth’s geological and atmospheric systems. Key topics include:

• Plate tectonics and earthquakes

• Soil formation and composition

• Atmospheric circulation and weather patterns

• Seasons and solar radiation

• El Niño and La Niña

Unit 5: Land and Water Use

Take a look at agriculture, mining, and urban sprawl to see how our choices shape the planet.

You’ll explore how humans use natural resources and the effects of those activities. Key topics include the following:

• Agricultural practices and irrigation methods

• Pesticide use and soil conservation

• Mining methods and impacts

• Urbanisation and land development

• Sustainable forestry and fishing

Salinization is a negative environmental impact caused by irrigation and a rising water table, as you will learn about in APES Unit 5: Land and Water Use

Unit 6: Energy Resources and Consumption

From coal to solar panels, this unit shows how our thirst for energy powers the world…and impacts the environment.

This unit examines how we generate and use energy and the environmental consequences of these processes. Key topics include:

• Renewable and nonrenewable energy sources

• Fossil fuels

• Nuclear energy

• Energy efficiency and conservation

• Electricity generation and fuel types

Unit 7: Atmospheric Pollution

Trace how pollutants travel through the air we breathe, from city smog to household chemicals.

You’ll study the types, sources, and impacts of air pollution. Key topics include:

• Primary and secondary pollutants

• Smog and photochemical pollution

• Thermal inversion

• Indoor air pollution

• Acid deposition

Unit 8: Aquatic and Terrestrial Pollution

Dive into the messy consequences of pollution and explore how science and policy work to clean things up.

This unit covers how pollutants affect aquatic and terrestrial ecosystems, as well as how pollution can be prevented or reduced. The unit covers the following key topics:

• Point and nonpoint source water pollution

• Solid and hazardous waste management

• Eutrophication and dead zones

• Bioaccumulation and biomagnification

• Sewage treatment and water remediation

Unit 9: Global Change

Zoom out for the big picture: climate, extinction, and the planetary-scale shifts shaping our future.

In this unit, you’ll explore large-scale environmental changes caused by natural and human activity. Key topics include:

• Stratospheric ozone depletion

• Greenhouse gases and climate change

• Ocean warming and acidification

• Invasive species and biodiversity loss

• Human impacts on biodiversity

What Are the Science Practices for AP Environmental Science?

In AP Environmental Science, it’s not just what you know—it’s what you can do with what you know. The exam is built around seven science practices that you will practice throughout the course. You’ll use these distinct skills to analyze, interpret, and solve environmental challenges. Let’s break them down:

1. Concept Explanation

You’ll get comfortable describing and explaining environmental ideas in writing. Whether it’s ecosystems or energy flows, you’ll learn to clearly connect concepts to real-world situations.

2. Visual Representations

Charts, diagrams, and models…this practice is all about interpreting visuals and explaining how they relate to environmental systems and challenges.

3. Text Analysis

APES isn’t just about data—it’s also about understanding perspectives. You’ll learn to identify an author’s viewpoint, assumptions, and logic, while evaluating how reliable and sound their arguments are.

4. Scientific Experiments

You’ll study experimental design and analysis. From identifying hypotheses to describing methods and assessing procedures, this practice helps you make sense of how environmental research is conducted.

5. Data Analysis

Get ready to interpret numbers and trends from tables and graphs. You'll identify patterns, explain relationships, draw conclusions, and connect data back to hypotheses and environmental issues.

6. Mathematical Routines

Numbers tell a story. This practice equips you to solve problems using math—whether it’s converting units, crunching numbers, or applying formulas, all with the correct units and precision.

7. Environmental Solutions

Here’s where it all comes together. You’ll identify problems and propose evidence-based solutions—while considering the pros, cons, and real-world impacts of your ideas.

By mastering these seven practices, you’ll be well-prepared to tackle the APES exam—and the complex environmental issues of the real world.

Top tips from an AP Environmental Science expert…

We asked AP Environmental Science expert and YouTuber Amy Fassler for her insights into the APES course:

“The interdisciplinary nature of the AP Environmental Science course makes it engaging and relevant but can also make it challenging to prepare for the exam because of the diverse range of topics and skills required to be successful on the exam.

As an APES teacher, exam question writer, and reader, the best advice I offer students as they prepare for the exam is to focus on the science practices.

The skills required for each practice are scaffolded so that you can progress from identifying, describing, and explaining environmental processes.

Knowing what skills are required to explain relationships represented in models or analyze data is essential to success on the exam.”

Amy Fassler, AP Environmental Science Educator (Marshfield High School, Wisconsin), College Board Consultant, HHMI BioInteractive Ambassador

Revision Resources for AP Environmental Science

To help you revise, we’ve created targeted resources that cover every unit of the AP Environmental Science course. These include:

• Concise study guides for each topic

• All past exam papers 

• Past paper-style MCQ and FRQ questions with mark schemes 

• Model answers to help you improve your exam technique

Improve Your Grades with Save My Exams

At Save My Exams, we know what it takes to succeed in AP Environmental Science. Our materials are written by teachers and readers who understand what students need—clear explanations, focused practice, and effective revision strategies.

Whether you’re aiming for a 5 in your final exam or just want to feel more confident going into your next class test, our resources can help you build the skills and knowledge that matter most.

Explore Our AP Environmental Science Revision Resources 

References

AP Environmental Science Course And Exam Description

Science Practices for the AP Environmental Science Course