4.11.3Additional lessons
Carbon Sequestration — IB Biology SL Revision Notes & Topical Questions
5 min read 4 parts Lesson 142 of 142
Part 1 of 4What Is Sequestration
Sequestration works by moving carbon from the atmosphere into stores where it can remain for long periods.
Definition
- The capture and long-term storage of carbon dioxide from the atmosphere, reducing the greenhouse effect.
Natural stores
- Trees, soils, peat bogs and oceans take up carbon through photosynthesis or dissolving.
Artificial storage
- Methods for capturing and storing carbon in other ways remain at an early stage of research.
Aim
- Increasing the size of sinks or protecting existing ones slows the rise in atmospheric carbon dioxide.
Scientific debate
- Scientists disagree whether fast-growing non-native plantations or slower rewilding with native species is the better option.
Part 2 of 4Natural Methods
Natural methods use biological processes and generally need land, time and support from governments or landowners.
Natural Methods
Reforestation
- Replanting trees in deforested land lets growing biomass store large amounts of carbon, as shown in Costa Rica's regrowth.
Afforestation
- Creating new forest on land that was not recently forested adds further carbon storage.
Peat restoration
- Filling drainage ditches keeps peat waterlogged and acidic, so decay stays slow and carbon remains locked up.
Protection
- Preventing harvesting of peat and trees stops stored carbon from returning to the air.
| Method | How carbon is stored | Limitation |
|---|---|---|
| Reforestation | Tree biomass and soil | Takes decades; needs land and funding |
| Peat restoration | Partly decayed plant matter | Slow to recover; requires water management |
Part 3 of 4Why Waterlogged Peat Stores Carbon
Different approaches to sequestration bring different benefits, and scientists disagree on which is best.
1
Plant matter falls into waterlogged, acidic and oxygen-poor ground in the bog.
2
Decay organisms are inhibited, so the dead plants decompose only partly.
3
Carbon stays locked in the peat, which slowly builds up in thickness.
4
Draining the bog for fuel or farming lets oxygen in, so decay organisms become active and release carbon dioxide.
5
Blocking ditches raises the water table, restoring the conditions that preserve peat.
6
Low oxygen and acidity limit decomposers, so the carbon in plant remains is not released as carbon dioxide.
Part 4 of 4Exam Checklist & Tips
4.11.3 – Key Points for the Exam
- Carbon sequestration The capture and long-term storage of atmospheric carbon dioxide.
- Reforestation Replanting trees in an area that has lost its forest.
- Afforestation Establishing forest in an area that was not forested before.
- Peat Partly decomposed plant matter that accumulates in waterlogged, acidic conditions.
- Carbon sink A store that takes up more carbon than it releases.
- Rewilding Restoring native ecosystems and letting natural processes recover.
Common Mistakes
- Saying all tree planting has equal value;
- native rewilding and fast-growing plantations differ in biodiversity benefits.
- Forgetting that draining peat releases carbon dioxide by decay and combustion.
- Assuming sequestration can fully offset continuing fossil fuel use.
- Confusing a carbon sink with a carbon source.
Last updated:
\n