topic 24 - the anthropocene and global climate change

Anthropocene

The current geological epoch in which human activity is the dominant influence on climate and environment, development of fossil fuel production, new technology and medicine

Anthropocene characterised by:

• Biodiversity loss

• Changing land use

  • Increased agriculture

• Increased GHGs in the atmosphere

• Increased use of technology

Key impacts of Anthropocene

• Upsetting the balance of biogeochemical cycles

• Changes to the composition of the atmosphere

• Loss of biological diversity

The Great Acceleration

1. Population growth - rapid increase in global human population since mid-20th century

2. Industrial and economic expansion - massive growth in production, consumption and energy use, leading to higher greenhouse gas emissions

3. Urbanisation and land use change - large scale deforestation, agricultural intensification, and urban development that transform natural environments

3 impacts of global temperature rise by 1.5 degrees

1. More extreme weather events - increased frequency and intensity of heatwaves, droughts and heavy rainfall leading to greater risks of bushfires, floods and crop failures

2. Ecosystem disruption and species loss - coral reefs (like the Great Barrier Reef) face severe bleaching, Arctic ice declines, and many plants and animals struggle to adapt or migrate, reducing biodiversity

3. Rising sea levels - melting glaciers and thermal expansion of ocean water cause sea levels to rise, increasing coastal erosion, flooding and displacement of low-lying communities

Positive feedback loop between sea ice melt and global temperature

Sea ice is highly reflective, has high albedo, bounces sunlight back into space

When global temperature rises, sea ice melts, exposing dark ocean water underneath

The dark ocean absorbs more sunlight, causes further warming

This extra warming leads to even more ice melt, reinforcing the cycle

Positive feedback loop - accelerates global warming

Habitat fragmentation

Habitat loss results in the division of large, continuous habitats into smaller, more isolated remnants

Breaks up native habitats, making it harder for them to support native plant and animal species

Due to human intervention

Types of fragmentation

Forest, roads and highways, fences

Forest fragmentation

Deforestation, affects the surrounding environment, divides the first habitat into smaller sections, changes the ecosystem

Eg. Deer drawn to areas of younger forest, attracting predators such as wolves to the smaller hunting ground, easier access to prey

Roads and highways fragmentation

More roads improve transportation, but divides the habitat and fast driving and large vehicles dangerous for animals

Wetlands often fragmented by roads: turtles crossing the road often hit due to slow moving nature

Fences fragmentation

Obstructs animals from crossing to other side in their habitat, creating a division in the middle of the habitat

Have to re-route to get to the other side

Nature based solutions

Protecting natural ecosystem, peak land, grassland, wetlands, forests, cleaning rivers, and out land, repairing damaged landscapes

• Restoring mangroves - protects coastlines from erosion and storm surges while providing habitats for marine life and storing carbon

• Reforestation - planting trees to absorb carbon dioxide, improve air quality and support biodiversity

Climate change: Adaptation

• Adjusting to the effects of climate change that are already happening or unavoidable

• Focuses on reducing harm or taking advantage of new conditions

• Eg. Building flood barriers and sea walls

• Developing drought-resistant crops

• Changing building designs to handle heatwaves

• Managing water use more efficiently

Climate change: Mitigation

Means reducing the cause of climate change, focuses on lowering greenhouse gas emissions or enhancing carbon sinks to slow or stop global warming

• Switching to renewable energy (solar, wind)

• Reforestation to absorb CO2

• Improving energy efficiency

• Using electric vehicles

Explain whether large-scale reforestation is a climate mitigation or climate adaptation approach

Mitigation means tacking the cause of climate change — mainly the buildup of greenhouse gases like CO2

Reforestation removes CO2 from the atmosphere through photosynthesis, storing it in trees and soil (a carbon sink)

This directly reduces atmospheric CO2 levels, helping to slow global warming

But also supports adaptation by improving resilience to heat, floods, and erosion

Explain whether urban tree planting is a climate mitigation or climate adaptation approach

Urban tree planting can actually serve both roles — but it’s primarily an adaptation approach with some mitigation benefits

As climate adaptation (main role):

• Trees cool cities by providing shade and through evapotranspiration, reducing the urban heat island effect

• Improve air quality and reduce stormwater runoff, helping cities cope with heatwaves and heavy rainfall

Helps people and infrastructure adapt to the effects of climate change

As climate mitigation (secondary role):

• Trees absorb CO2 from the atmosphere → helps reduce greenhouse gases slightly

Contributes to slowing global warming, but impact is smaller compared to large-scale forests

Two common pitfalls in nature based solutions implementation

1. ignoring social and equity issues - projects may exclude or disadvantage local or indigenous communities but not involving them in planning or decision making, leading to unequal benefits or even displacement

2. Poor understanding of the ecosystem context - implementing the wrong type of vegetation or restoration method for the local environmental (for example, planting non native trees) can harm biodiversity and disrupt existing ecosystems instead of helping them