Human Footprint

Human Footprint

There are more than **8 billion** of us, each using resources and making waste. That footprint is reshaping ecosystems everywhere. **Biodiversity** is the **variety of all the different species** of organisms in an ecosystem, or on Earth. A **high** biodiversity makes an ecosystem **more stable** and **sustainable**, because species are **less dependent** on any single other species for food, shelter or maintaining their environment. This module maps our impact. Pollution, land use, deforestation and warming, and, crucially, what can be done to protect it.

Why it matters

Why does a high level of biodiversity help an ecosystem stay stable?

• Species are less dependent on any single other species to survive
• There are fewer organisms to feed
• It removes all competition between species
• It makes the climate warmer

More people, more waste

As the population grows and living standards rise, we use more resources and produce more waste. Without proper handling that causes **pollution**, which kills plants and animals and so reduces biodiversity. Three places to name:

Where does it pollute?

Running out of room

Humans reduce the land available to other species in two distinct ways, and a question naming one rarely wants the other. Destroying **peat bogs** for compost and farmland is especially damaging: it wrecks a rare habitat **and** releases stored carbon dioxide.

What deforestation does

Pick the TWO consequences of large-scale deforestation.

• Loss of habitat and biodiversity
• Release of carbon dioxide, a greenhouse gas
• More carbon dioxide absorbed from the air
• Cooler global temperatures

A warming world

Rising levels of **greenhouse gases**, mainly **carbon dioxide** and **methane**, are causing **global warming**. For living things this means: • **loss of habitat** (e.g. melting ice, flooding of low-lying land) • changes to the **distribution** of species, as areas become newly suitable or unsuitable • changes to **migration** patterns, and threats to **food production**: all reducing biodiversity.

Follow the warming

Rising temperatures are melting the Arctic sea ice that polar bears hunt seals from. Trace the effects.

• The sea ice the bears hunt from is melting away. What happens to their habitat?
• With less ice to hunt from, what happens to the polar bear population?
• Meanwhile, warmer conditions let some insects spread further north than ever before. What is this an example of global warming changing?

Name the fixes

Endangered species can be supported by _____ programmes. Rare habitats can be protected and _____. On farmland where only one crop is grown, reintroducing _____ restores habitat and food. Governments and businesses can cut carbon emissions and reduce _____, and resources can be _____ rather than sent to landfill.

Give nature a hand

A farmer grows a single crop across a huge field. Which action would most directly help local biodiversity?

• Reintroduce hedgerows and field margins around the crop
• Plant even more of the same single crop
• Pave the edges of the field
• Drain a nearby peat bog for more land

Follow the chain

Put the consequences of large-scale deforestation into the order they follow one another.

• Trees are cleared for cattle, rice or biofuel crops
• Less carbon dioxide is absorbed, because there are fewer trees
• Carbon dioxide is released as the felled trees are burned or decompose
• Greenhouse gas levels rise and global warming increases
• Habitats are lost and shift, so biodiversity falls

Explain the impact

Explain how large-scale deforestation both contributes to global warming and reduces biodiversity. Take each effect through to its consequence.

• Say what happens to the carbon dioxide trees would have absorbed
• Say what happens to the carbon stored in the trees themselves
• Link the warming and the habitat loss to a named effect on species

In the exam

Footprint mapped. Grade-9 habits for human impact: • Argue **biodiversity's** importance: high biodiversity → more **stable, sustainable** ecosystems. • Link each activity to a **specific** consequence. Deforestation → habitat loss **and** CO2 release; peat destruction → stored CO2 released. • Global warming changes species **distribution** and **migration**, not just temperature, and name real fixes (breeding programmes, habitats, hedgerows, recycling).