Carbon Cycle and Climate Change

• Key concepts are the carbon cycle, climate change, extracting metals, global warming, and recycling.
• Human activities and their environmental impact is a connecting theme.

The Carbon Cycle

• Carbon dioxide (CO2) levels remained relatively stable before 1960, suggesting a natural balance.

Processes Adding CO2 to the Atmosphere

• Respiration transfers energy from food in plants and animals, producing CO2 as waste: glucose + oxygen → carbon dioxide + water.
• Combustion is the burning of fuels (wood, petrol, methane) with oxygen, producing CO2; for methane: methane + oxygen → carbon dioxide + water.

Processes Removing CO2 from the Atmosphere

• Photosynthesis uses CO2 and water to create glucose, releasing oxygen: carbon dioxide + water → glucose + oxygen.
• Oceans absorb CO2, utilized by marine plants.
• Hotter oceans absorb less CO2.
• Carbon sinks absorb and store carbon compounds
• Oceans, soil, and forests are examples of carbon sinks.
• Human combustion activities disrupt the natural balance by adding CO2.

Climate Change

• Climate change refers to long-term shifts in weather patterns.
• Changes in rainfall, cause flooding in some areas, droughts/heatwaves and crop failures in others
• Melting Glaciers and polar ice is occuring, leading to sea level rise and flooding of coasts
• Climate change leads to biodiversity loss and potential extinctions.
• Transitioning to renewable energy from solar is a preventative measure
• Reducing reliance on cars and overconsumption can prevent climate change

Extracting Metals

• Materials originate from Earth's crust, atmosphere, or oceans.
• Minerals are naturally occurring metals and their compounds.
• Ore is rock containing enough metal to make extraction profitable.
• The reactivity series dictates metal extraction methods.
• Magnesium is very reactive.
• Copper is the least reactive.
• Carbon is a key element in the reactivity series.
• Metals less reactive than carbon are extracted by heating their ore with carbon to form carbon dioxide.
• An example of this is : Copper oxide + carbon → copper + carbon dioxide.
• Reactive metals like aluminum are extracted using electrolysis which uses electricity to split a compound into its elements.
• Electrolysis of aluminum oxide forms aluminum and oxygen; this is very expensive.
• Metal extraction is resource-intensive and can release CO2.
• Electrolysis for reactive metals has high energy demands, potentially increasing greenhouse gas emissions if electricity is from fossil fuels.

Global Warming

• The atmosphere's composition is approximately 78% nitrogen, 21% oxygen, 1% argon, and 0.04% carbon dioxide.
• Carbon dioxide, water vapor, and methane are greenhouse gases, which come from cars, factory gas, cow farts, burning fossil fuels, and respiration in cells.
• The atmosphere contains greenhouse gases which trap heat
• The sun warms Earth, which releases heat. Greenhouse gases trap some heat, maintaining habitable temperatures.
• "We need some greenhouse gasses in the atmosphere to keep the earth warm, but we are putting to many into the atmosphere rising earths temperature."

Recycling

• Recycling is the process of collecting and processing used materials for reuse.
• Paper is recycled to make new paper.
• Plastic bottles are recycled to make fleeces.
• Aluminum cans are recycled to make aluminum foil.

Advantages of Recycling

• Resources will last longer because of Recycling
• Recycling uses less energy compared to using new materials.
• Extracting 1 kg of aluminum from ore requires approximately 255 MJ of energy, while recycling 1 kg of aluminum requires only 15 MJ.
• Recycling reduces waste and pollution.
• Extracting aluminum ore creates dangerous "red mud" waste.

Disadvantages of Recycling

• Some people find rubbish separation inconvenient.
• Lorries that collect recycling use fuel and create pollution.

How to Recycle Aluminum

• Shredding, melting in a furnace, pouring into moulds to make aluminium ingots heating to soften, and rolling into thin sheets
• Ways plastic ends up: landfill, the ocean, or recycled

Overall Connections and Implications

• Burning fossil fuels is a central theme, raising atmospheric CO2, enhancing the greenhouse effect, and leading to climate change.
• Extracting natural resources, especially metals, can be energy-intensive and create waste.
• Recycling is a sustainable alternative, which conserves resources, reduces energy demand, and reduces pollution.
• Oceans act as a carbon sink but are affected by rising temperatures that reduces CO2 absorption while also suffering pollution from plastic waste
• Sustainable practices (renewable energy, reduced consumption, increased recycling) are key to mitigating human impact on the environment.

Key Terms

• Atmosphere: The layer of gases surrounding a planet/body, held by gravity.
• Carbon Cycle: The biogeochemical cycle exchanging carbon among Earth's systems.
• Carbon Dioxide (CO2): A colourless, odourless gas.
• Carbon Sink: A reservoir storing carbon compounds, removing CO2 from the atmosphere.
• Climate Change: Long-term shifts in temperatures and weather patterns since the 1800s, mainly due to burning fossil fuels.
• Combustion: Burning a substance with an oxidant (usually oxygen) to produce heat and light.
• Displacement Reaction: A reactive element displacing a less reactive element from its compound.
• Electrolysis: Using electric current to drive a non-spontaneous chemical reaction, commercially used to extract elements from ores.
• Fossil Fuels: Fuels formed from the remains of living organisms (coal, oil, natural gas).
• Glucose: A simple sugar and energy source produced by photosynthesis.
• Greenhouse Effect: A planet's atmosphere warming its surface via greenhouse gases trapping outgoing energy.
• Greenhouse Gases: Atmospheric gases trapping heat (water vapor, CO2, methane, nitrous oxide, ozone, fluorinated gases).
• Mineral: Naturally occurring substance with a specific composition and crystal structure.
• Ore: Rock containing enough minerals with economically important metals to warrant extraction.
• Photosynthesis: Plants using sunlight, water, CO2 to create glucose and oxygen.
• Reactivity Series: Metals arranged by their ease of reaction.
• Recycling: Converting waste materials into new materials.
• Respiration: Cells releasing energy from food (glucose) by oxidation, producing CO2 and water.
• Word Equation: Representing a chemical reaction using reactant and product names (e.g., "Methane + oxygen → carbon dioxide + water").