Geoengineering is the deliberate, large-scale technological intervention in Earth’s climate system to limit climate change. In IB ESS, it is classified as a mitigation strategy, but it is often described as treating the symptoms of climate change rather than removing its underlying causes.
This is HL-only content from Subtopic 6.3, Climate changefrommitigation and adaptation.
Geoengineering proposals work through two broad mechanisms:
| Approach | Mechanism and example | Main limitation |
|---|---|---|
| Carbon dioxide removal (CDR) | Removes atmospheric carbon dioxide and stores it. Examples include direct air capture and ocean fertilization. | Removal may be slow, expensive or difficult to maintain at the required scale. Storage may not be permanent. |
| Solar radiation management (SRM) | Reflects more incoming solar radiation back into space. Stratospheric aerosol injection, modelled partly on volcanic eruptions, is an example. | It does not reduce atmospheric carbon dioxide or ocean acidification. Stopping suddenly could cause rapid warming. |
Geoengineering differs from adaptation, which reduces vulnerability to climate impacts without directly limiting climate change. For example, constructing sea walls is adaptation, while removing atmospheric carbon dioxide is mitigation.
Geoengineering is controversial because Earth’s climate is a complex system. Large interventions may produce unintended consequences, including altered precipitation patterns, ecosystem disruption and unequal regional effects. This creates an environmental justice issue: countries that did not authorize an intervention might experience its greatest risks.
Perspectives also affect its acceptability. A technocentric perspective may support technological innovation, while an ecocentric perspective may oppose manipulating natural systems. An anthropocentric perspective may accept geoengineering if its benefits to societies clearly outweigh its risks.
A common misconception is that geoengineering can replace emissions reductions. It cannot reliably substitute for decarbonization because many techniques do not address continued greenhouse gas emissions and may create new risks.
Exam technique: For an HL evaluate or discuss question, explain the mechanism, weigh benefits against limitations, include named examples, consider stakeholder perspectives and environmental justice, and finish with a supported conclusion. Do not confuse geoengineering with adaptation.
