Key Questions Flashcards
When did life start to appear and what was the impact of this on oxygen in the atmosphere?
About 2.7 billion years ago, amount of atmospheric oxygen increased as it was released during photosynthesis
How has the amount of nitrogen in the atmosphere changed over time
Increased slowly as it is a very stable molecule
Why can scientists not be sure of the earths early atmosphere?
It was billions of years ago and evidence is limited
What is the current composition of the atmosphere?
80% nitrogen 20% oxygen and trace amounts of other gases such as carbon dioxide,water vapour and noble gases
What is a greenhouse gas ?
A gas that traps radiation from the sun
What type of radiation do greenhouse gases absorb?
Longer wavelength infrared radiation
Name three greenhouse gases
Water vapour, methane and carbon dioxide
Give two ways recent human activities have increased the amount of atmospheric carbon dioxide
Deforestation and burning of fossil fuels
Give two ways recent human activities
have increased the amount of atmospheric methane
Rice farming and cattle farming
What is global warming ?
An increase in the overall global average temperature
What is global climate change ?
The change in long term weather patterns across the planet
