How does climate change both drive and result from land cover change, and how can these processes be managed?
the relationship between climate change and land cover change, including how land cover change contributes to the enhanced greenhouse effect and how a warming climate alters land cover, and the responses to these processes
A VCE Geography Unit 3 answer on how climate change and land cover change interact: how clearing forests and melting ice add to the enhanced greenhouse effect, and how warming in turn shifts land cover, with responses, using the Arctic and Australian examples.
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What this dot point is asking
VCAA wants you to understand land cover change not just as a set of separate processes (deforestation, melting ice, desertification, salinity) but as something tied to global climate. You should be able to explain how land cover change adds to warming and how warming changes land cover, and evaluate responses.
The enhanced greenhouse effect in brief
The natural greenhouse effect keeps Earth habitable: gases such as carbon dioxide and methane trap outgoing heat. Human activity has raised the concentration of these gases, strengthening the effect and warming the planet. This is the enhanced greenhouse effect, and land cover change is one of its drivers as well as one of its outcomes.
How land cover change adds to warming
- Deforestation releases carbon stored in trees and soil when forests are cleared or burned, and removes a sink that would otherwise absorb carbon dioxide.
- Draining wetlands and peatlands, among the densest carbon stores on Earth, releases large amounts of carbon and methane.
- Reduced ice and snow lowers the surface albedo: bright ice reflects sunlight, while the darker land or ocean exposed beneath absorbs more heat, warming the surface further.
- Land degradation and desertification reduce vegetation that would store carbon and can release soil carbon to the atmosphere.
How warming changes land cover
- Melting ice and snow shrinks glaciers, ice sheets and sea ice, replacing white cover with rock or water.
- Shifting vegetation zones push tree lines and biomes poleward and upslope as temperatures rise.
- Expanding drylands as warming and changing rainfall intensify aridity, contributing to desertification at desert margins.
- More frequent and intense fire converts forest to scrub or grassland, as seen in Australia's severe bushfire seasons.
Feedback loops
The two-way relationship creates feedback loops that amplify change. The ice-albedo feedback speeds polar warming. Thawing permafrost releases stored carbon and methane, adding to warming that thaws more permafrost. A drying Amazon releases carbon while losing its capacity to absorb it. These loops mean land cover change and climate change can accelerate one another, which is why a tipping point in one system can be so serious.
Impacts on people and the environment
Environmentally, the combined effect reshapes ecosystems, threatens species that cannot move or adapt, and raises sea levels through melting land ice. For people, shifting land cover affects agriculture, water supplies from glacier-fed rivers, and the safety of low-lying and fire-prone communities. Because emissions and impacts cross borders, the consequences are global even where the land cover change is local.
Responses
- Reducing emissions through renewable energy and efficiency tackles the underlying driver of warming.
- Protecting carbon-storing land cover, especially forests, peatlands and wetlands, prevents stored carbon being released.
- Restoration, such as reforestation, rewetting peatlands and revegetation, rebuilds carbon sinks.
- International agreements, such as the Paris Agreement, coordinate emission cuts and forest protection across countries.
- Adaptation, including managing fire and water and protecting vulnerable communities, addresses changes that are already locked in.