C6.3 - Interpreting and Interacting with Earth's systems

What was the early Earth like?

A hot molten surface with intense volcanic activity $

How did the early atmosphere form?

Volcanoes released gases including CO₂, H₂O vapour, CH₄, NH₃, H₂ N₂

Main gases in the early atmosphere

Carbon dioxide, water vapour, methane, ammonia; very little oxygen $

What happened as Earth cooled?

Water vapour condensed → oceans formed $

How was CO₂ removed from the early atmosphere?

Dissolved in oceans → formed carbonates; used by early photosynthetic organisms $

Early atmosphere diagram

[DRAW: volcano releasing CO₂, H₂O, CH₄, NH₃ into early atmosphere] $

How did oxygen first appear in the atmosphere?

Photosynthetic organisms produced oxygen $

How did oxygen levels increase?

Built up over millions of years as photosynthesis continued $

Why was oxygen important for life?

Allowed evolution of aerobic organisms $

Photosynthesis equation (word) and symbol

Carbon dioxide + water → glucose + oxygen (sunlight) $

6CO2+6H2O→C6H12O6+6O2.

What is the greenhouse effect?

Natural process where greenhouse gases trap infrared radiation and warm Earth $

What type of radiation enters Earth’s atmosphere?

Short‑wavelength radiation (visible + UV) $

What type of radiation is re‑emitted by Earth?

Long‑wavelength infrared radiation $

How do greenhouse gases warm the Earth?

Absorb IR radiation and re‑radiate it in all directions $

Main greenhouse gases

CO₂, CH₄, H₂O vapour $

Sources of carbon dioxide

Burning fossil fuels, deforestation $

Sources of methane

Cattle farming, rice fields, landfill, decay of organic matter $

Greenhouse effect diagram

[DRAW: Sun → Earth → IR trapped by greenhouse gases] $

What is climate change?

Long‑term change in Earth’s temperature and weather patterns $

Main cause of recent climate change

Increased greenhouse gases from human activity $

Evidence for climate change

Rising CO₂ levels + rising global temperatures $

Graph evidence diagram

[DRAW: rising CO₂ graph + rising temperature graph] $

Why is climate data uncertain?

Incomplete historical data, natural climate variation, assumptions in models $

Natural factors affecting climate

Volcanic activity, solar radiation changes $

Effects of climate change

Rising sea levels, melting ice, extreme weather, habitat loss, migration/extinction, crop failure $

Impacts on humans

Flooding, food insecurity, health risks, economic damage $

Mitigation strategies

Reduce emissions, renewable energy, energy efficiency, reforestation, carbon capture, international agreements $

Examples of international agreements

Paris Agreement $

Examples of carbon capture

Storing CO₂ underground or in geological formations $

Major atmospheric pollutants

CO₂, CO, SO₂, NOₓ, particulates $

Source of carbon dioxide

Complete combustion of fuels $

Source of carbon monoxide

Incomplete combustion of fuels $

Why is carbon monoxide dangerous?

Binds to haemoglobin → prevents oxygen transport $

Source of sulfur dioxide

Burning fuels with sulfur impurities $

Source of nitrogen oxides

Reaction of N₂ and O₂ at high temperatures (car engines) $

Source of particulates

Incomplete combustion → soot particles $

Equation for CO₂ formation

C + O₂ → CO₂ $

Equation for CO formation

2C + O₂ → 2CO $

Equation for SO₂ formation

S + O₂ → SO₂ $

Equation for NO formation

N₂ + O₂ → 2NO $

Equation for NO₂ formation

2NO + O₂ → 2NO₂ $

Environmental effects of CO₂

Global warming $

Environmental effects of CO

Toxic; fatal at high levels $

Environmental effects of SO₂ and NOₓ

Acid rain; damages buildings, kills plants, harms aquatic life $

Environmental effects of particulates

Global dimming + respiratory problems $

Acid rain diagram

[DRAW: factories releasing SO₂/NOₓ → clouds → acid rain damaging trees/buildings] $

Acid rain effect on buildings

Erodes limestone and marble $

Acid rain effect on ecosystems

Acidifies lakes; kills fish and plants $

What is potable water?

Water safe for humans to drink; not chemically pure $

Requirements for potable water

Low levels of dissolved substances + no harmful microbes $

Steps to produce potable water (UK)

Choose fresh water source → filter → sterilise $

Methods of sterilisation

Chlorine, ozone, UV light $

Why is sterilisation needed?

To kill harmful microorganisms $

Why is filtration needed?

Removes solid particles $

What is desalination?

Removing salt from seawater to produce potable water $

Two methods of desalination

Distillation and reverse osmosis $

Why is desalination expensive?

Requires large amounts of energy $

What is distillation?

Boiling water → condensing steam to remove salts $

What is reverse osmosis?

partially permeable membrane allows water through but not ions

Why is water quality monitored?

Ensure pH, salt levels, and microbes are safe $

Tests for water quality

pH test, test for dissolved salts, microbial analysis $

Potable water diagram

[DRAW: filtration → sterilisation → potable water] $

Desalination diagram

[DRAW: distillation + reverse osmosis membrane] $