---
title: "Carbon Sequestration — AP Enviro Definition & Exam Guide"
description: "Carbon sequestration is the long-term capture and storage of CO2 by forests, wetlands, and oceans, a regulating ecosystem service that fights climate change."
canonical: "https://fiveable.me/ap-enviro/key-terms/carbon-sequestration"
type: "key-term"
subject: "AP Environmental Science"
unit: "Unit 2"
---

# Carbon Sequestration — AP Enviro Definition & Exam Guide

## Definition

Carbon sequestration is the process of capturing carbon dioxide from the atmosphere and storing it long-term in forests, soils, wetlands, or oceans instead of letting it stay in the air. On the AP Enviro exam, it shows up as a regulating ecosystem service tied to forests and wetlands.

## What It Is

Carbon sequestration is when [carbon dioxide](/ap-enviro/key-terms/carbon-dioxide "fv-autolink") gets pulled out of the [atmosphere](/ap-enviro/unit-4/earths-atmosphere/study-guide/7Z9K5q4df3Hvtvuh33x9 "fv-autolink") and locked away somewhere it won't warm the planet. Plants do this naturally through photosynthesis, storing carbon in their wood, roots, and the soil around them. Wetlands and oceans do it too, holding huge amounts of carbon in waterlogged soils and dissolved in seawater.

Think of a forest as a giant carbon battery. As trees grow, they bank carbon in their tissue and hold it for decades. Cut the forest down or drain a wetland, and that stored carbon gets released back into the air. That's why sequestration sits at the center of two big AP themes: it's a free service nature provides (a **regulating [ecosystem](/ap-enviro/unit-2/natural-disruptions-ecosystems/study-guide/QpHtIjQYZUMm1mTZghkU "fv-autolink") service**), and it's a lever humans can pull to slow climate change. The catch is that human activity often does the opposite, releasing stored carbon faster than ecosystems can recapture it.

## Why It Matters

Carbon sequestration ties together three units, which is exactly why it's a great cross-topic anchor. In **[Unit 2](/ap-enviro/unit-2 "fv-autolink") (Ecosystem Services)**, it's a classic regulating service under learning objective [[AP Enviro](/ap-enviro "fv-autolink") 2.2.A], and disrupting it has economic and ecological consequences per [AP Enviro 2.2.B]. In **Unit 5 (Land and Water Use)**, reforestation and sustainable forestry are mitigation methods under [AP Enviro 5.17.A] that boost how much carbon forests store. In **Unit 8 (Aquatic and Terrestrial Pollution)**, wetlands and mangroves store carbon while also filtering water and buffering floods, which connects to the human impacts in [AP Enviro 8.4.A]. The exam loves these connections because sequestration links the living world, land use, and pollution back to climate change.

## Connections

### Reforestation (Unit 5)

Reforestation is sequestration in action. Planting trees rebuilds the carbon battery you lost to [deforestation](/ap-enviro/key-terms/deforestation "fv-autolink"), pulling CO2 out of the air as the new forest grows. EK STB-1.G.1 lists it as a top method for mitigating deforestation.

### Ecosystem Services (Unit 2)

Sequestration is the textbook example of a regulating ecosystem service, the category that controls climate and [air quality](/ap-enviro/key-terms/air-quality "fv-autolink"). When you clear a forest or drain a wetland, you don't just lose timber, you lose the free carbon storage that service provided.

### Wetlands and Mangroves (Unit 8)

Wetlands store carbon in waterlogged soils that decompose slowly, making them carbon-storage powerhouses. Draining or developing them for commercial use (EK STB-3.E.3) releases that carbon, so [wetland](/ap-enviro/key-terms/wetland "fv-autolink") protection doubles as climate mitigation.

### [Biogeochemical Cycles (Unit 4)](/ap-enviro/key-terms/biogeochemical-cycles)

Sequestration is one step in the carbon cycle. CO2 moves from the atmosphere into a long-term sink (a forest, soil, or the ocean), and understanding that flow helps you reason about why disturbing a sink speeds up warming.

## On the AP Exam

You'll most often meet carbon sequestration inside ecosystem-service and land-use questions rather than as a stand-alone vocab term. MCQ stems ask you to identify which service is lost when wetlands are removed for urban development, or which scenario best mitigates deforestation through reforestation. In FRQ design-an-investigation or propose-a-solution prompts, naming carbon sequestration as a benefit of forests or wetlands earns you a regulating-service point. Expect trade-off questions too, like whether to preserve a forest or convert it to farmland, where you weigh the carbon storage and other services against economic gain. No released FRQ has used the exact phrase, but the reasoning, connecting storage of carbon to climate mitigation, is exactly what these prompts reward.

## Carbon sequestration vs Carbon offset

Sequestration is the physical act of storing carbon (a tree banking CO2). A carbon offset is a financial credit you buy to cancel out emissions, often by paying for sequestration somewhere else, like funding a reforestation project. So sequestration can be the activity an offset pays for, but the offset itself is the accounting tool, not the storage.

## Key Takeaways

- Carbon sequestration is the long-term capture and storage of CO2 in forests, soils, wetlands, and oceans, which keeps it out of the atmosphere.
- It counts as a regulating ecosystem service under [AP Enviro 2.2.A] because it helps control the climate.
- Reforestation and sustainable forestry (EK STB-1.G.1) increase sequestration, while deforestation releases stored carbon back into the air.
- Wetlands and mangroves are major carbon sinks, so draining or developing them (EK STB-3.E.3) undoes their climate benefit.
- On the exam, name sequestration as a climate-mitigation benefit when you justify protecting forests or wetlands, and weigh it against economic uses in trade-off questions.

## FAQs

### What is carbon sequestration in AP Environmental Science?

It's the process of capturing CO2 from the atmosphere and storing it long-term in forests, soils, wetlands, or oceans. On the exam it shows up as a regulating ecosystem service and a climate-change mitigation method tied to forests (Topic 5.17) and wetlands (Topic 8.4).

### Is carbon sequestration the same as a carbon offset?

No. Sequestration is the actual physical storage of carbon, like a growing forest banking CO2. A carbon offset is a financial credit you buy to cancel emissions, and it often pays for sequestration projects, but the offset is the accounting tool, not the storage itself.

### How do wetlands sequester carbon?

Wetlands hold carbon in their waterlogged soils, where the lack of oxygen makes dead plant material decompose very slowly, so carbon stays locked up for a long time. That's why draining wetlands for development releases stored carbon and removes a climate benefit (EK STB-3.E.3).

### Why does deforestation hurt carbon sequestration?

Trees store carbon in their wood and roots, so when a forest is cut down or burned, that stored carbon goes back into the atmosphere and the forest stops pulling in new CO2. Reforestation reverses this by rebuilding the carbon sink (EK STB-1.G.1).

### Which ecosystem service category does carbon sequestration belong to?

It's a regulating ecosystem service, the category that controls climate, air quality, and similar processes, under [AP Enviro 2.2.A]. The other three categories are provisioning, cultural, and supporting.

## Related Study Guides

- [2.2 Ecosystem Services](/ap-enviro/unit-2/ecosystem-services/study-guide/ar6VaapmuP8HSgvCJrvA)

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