Topic 9 Atomosphere Flashcards
What gases made up the Earth’s early atmosphere?
Mostly carbon dioxide, with little or no oxygen, plus nitrogen, water vapour, methane, and ammonia.
What caused the early atmosphere to form?
Intense volcanic activity released gases like CO₂, water vapour, and nitrogen.
: How did oceans form on Earth?
Water vapour in the atmosphere condensed as the Earth cooled, forming liquid water and oceans.
How did oceans reduce the amount of carbon dioxide in the atmosphere?
CO₂ dissolved in the oceans and formed carbonates, which were deposited as sediments.
How did photosynthesis change the atmosphere?
Early algae and plants used CO₂ and released O₂, increasing oxygen levels.
What are the main gases in the modern atmosphere?
78% nitrogen, 21% oxygen, <1% other gases (including CO₂, argon, and water vapour).
What role did marine organisms play in reducing CO₂?
Marine organisms used CO₂ to form calcium carbonate shells, which became limestone after they died.
What are fossil fuels made from?
Remains of plants and animals buried under sediments and compressed over millions of years.
Why did nitrogen levels in the atmosphere increase?
Volcanic activity released nitrogen, which built up because it is unreactive.
What is the link between atmospheric changes and life on Earth?
The evolution of photosynthesising organisms changed gas levels, allowing complex life to develop.
: How did crude oil and natural gas form?
From plant material buried in swamps, compressed over millions of years in absence of oxygen.
What is the role of sedimentary rocks like limestone in the carbon cycle?
They lock up carbon from dead marine organisms, reducing atmospheric CO₂.
How did coal form?
From plant material buried in swamps, compressed over millions of years in absence of oxygen.
What are the main greenhouse gases?
Carbon dioxide (CO₂), methane (CH₄), and water vapour (H₂O).
What do greenhouse gases do in the atmosphere?
They absorb outgoing infrared radiation, keeping the Earth warm – known as the greenhouse effect.
What is the greenhouse effect?
It’s the process where greenhouse gases trap heat in the atmosphere, maintaining Earth’s temperature.
How does human activity increase carbon dioxide levels?
Through burning fossil fuels (coal, oil, gas) and deforestation.
How does human activity increase methane levels?
From landfills, cattle farming, and rice fields.
What is global warming?
A gradual increase in Earth’s average temperature due to more greenhouse gases.
What are potential effects of climate change?
Melting ice caps, rising sea levels, extreme weather, habitat loss, and reduced crop yields.
Why is climate change difficult to fully understand?
Because the climate is complex, and many factors and feedback systems are involved.
What is a carbon footprint?
The total amount of greenhouse gases released by an individual, product, or activity over its lifetime.
How can we reduce carbon footprints?
Use renewable energy, improve energy efficiency, reduce waste, and plant more trees.
Why is reducing greenhouse gas emissions challenging?
It can be costly, affect economic growth, and needs global cooperation.
