what are the proportions of gases in the atmosphere today?
- 80% nitrogen
- 20% oxygen
- small proportions of other gases, like carbon dioxide, water vapour and noble gases
Theories suggest that the first billion years of the Earth’s existence included intense volcanic activity. This released what?
- carbon dioxide
- nitrogen
- a little methane
- a little ammonia
- may have also released water vapour which formed oceans
- NO oxygen
How has the Earth’s atmosphere changed over time?
- As earth cooled, water vapour condensed and formed oceans
- CO2 dissolved in the oceans which formed hard precipitates (solids). Some of it was used by sea creatures to make shells, and these later formed rocks
- 2.7billion years ago, algae, and later plants, began producing O2 by photosynthesis, which also reduced CO2 levels. Animals evolved as oxygen levels rose
- Fossil fuels contain large amounts of carbon, which came from CO2 in the early atmosphere
Name the 3 main greenhouse gases
- water vapour
- carbon dioxide
- methane
Greenhouse gases like CO2 allow ___ from the sun to pass through the ____
- shortwave radiation (uv)
- atmosphere
The energy of the radiation is ___ when it reaches the ____ of the earth
- absorbed
-surface
The surface of the earth now ____ the energy as ____ radiation such as infrared
- radiates
- long wavelength
CO2 then ____ some of the outgoing longwave radiation, causing the atmosphere to ____
- absorbs
- warm up
without the greenhouse affect, the earth would be _____
too cold to sustain life
what are the effects of climate change?
- weather pattern changing (flooding/droughts)
- extreme weather (e.g. hurricanes)
- ice caps and glaciers melting
- sea levels rising, causing flooding
- desertification
- reduced yield of crops
- habitats changing
Carbon dioxide
Cause: Complete combustion
Problem: global warming
Carbon monoxide
Cause: incomplete combustion
Problem: toxic gas, colourless and odourless
Sulfur dioxide
Cause: oxidation of sulfur impurities in fossil fuels
Problem: acid rain, respiratory problems
Oxides of nitrogen
Cause: oxidation of nitrogen in air at high temperatures in a vehicle engine
Problem: acid rain and respiratory problems
Carbon particulates
Cause: burning diesel
Problem: global dimming, health problems
How is human activity increasing carbon dioxide levels?
- combustion of fossil fuels
- deforestation
How is human activity increasing methane levels?
- farming cattle
- growing rice
- use of landfill
What is carbon footprint?
the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
how can you reduce carbon footprint directly?
- using “green” energy sources that don’t emit CO2 (i.e. solar or wind power)
how can you reduce carbon footprint indirectly?
- insulating buildings so less heating is required, requiring less fossil fuels to be burnt
