Topic 6: Global Challenges - Subtopic 3: Interpreting & Interacting with Earth Systems

• Surface of Earth was molten for million of years, no atmosphere • Cooling began and molten materials solidified to form land masses • Volcanoes formed on land masses • Released gases through violent eruptions • Gravity prevented gases escaping, forming atmosphere

• Similar to Venus/Mars, mainly CO₂ • Intense volcanic activity, large amount of CO₂, water vapour as well as N₂, H₂, NH₃ and CH₄ • Little or no oxygen present

• When surface still hot, still in gaseous state • Cooled sufficiently, water vapour condensed and fell to surface to form oceans • CO₂ is water soluble gas so dissolves readily and dissolved into oceans • Carbonate substances precipitated to form sediments

• Primitive plants and algae photosynthesise • Releases O₂ and takes in CO₂, long period of time O₂ in atmosphere increase and CO₂ decrease • As levels increased, more complex life forms evolved • Marine algae responsible for about 90% of all atmospheric oxygen produced

~ 78% Nitrogen ~ 21% Oxygen ~ 0.04% Carbon Dioxide ~ 0.96% Other Gases

• Formed from dead plankton and algae • Sank to the seafloor, buried under sediment, and transformed by heat and pressure into organic-rich source rocks

• Formed from dead plant material that accumulated in swamps and bogs • Plant matter was buried under sediment and transformed over millions of years into coal through heat and pressure

• Formed from calcium carbonate shells and skeletons of marine organisms that settled on the seafloor • Deposits were compacted and cemented into sedimentary rock

• Carbon from organic remains is locked in sedimentary rocks—in crude oil, coal, and limestone—as long-term carbon stores • Preventing return to atmosphere

• Carbon Dioxide • Methane • Water Vapour

Maintain temperatures on Earth high enough to support life

1) Sun emits short-wavelength radiation which warms Earth 2) Earth loses heat by emitting long-wavelength radiation 3) Greenhouse Gases absorb some of the long-wavelength radiation 4) Re-radiate this thermal radiation in all directions, including back to Earth, warms atmosphere

Humans are increasing the levels of greenhouse gases in atmosphere, warming Earth too much, trapping extra heat energy

• Burning fossil fuels for electricity • Deforestation, reduces trees absorbing CO₂ by photosynthesis • Thermal decomposition of carbonate rocks

• Cattle producing methane, reared for humans (meat or milk) • Landfill sites, decay of waste in landfill by microorganisms produce methane

• Rising Sea Levels: Melting polar ice caps, destructive erosion to coastal regions, habitat destruction, flooding • Intense Droughts: Crop failure, collapse of agricultural production • Storms: More energetic and destructive as more moisture in atmosphere • Extreme Heatwaves and Rainfall: Lack of reliable freshwater, loss of life and destruction of infrastructure and ecosystems

1) Use less fossil fuels, switch to bio fuels 2) Use renewables 3) Use carbon capture and storage

The combustion of fossil fuels.

• Coal, oil, natural gas, oil shales, and tar sands • By fractional distillation

• Petrol → cars • Kerosene → aircraft • Diesel → some cars, trucks, heavy vehicles

Carbon, hydrogen, and small amounts of sulfur

Carbon dioxide, carbon monoxide, oxides of nitrogen, oxides of sulfur

Unburned hydrocarbons and carbon particulates (soot)

It binds to haemoglobin, preventing oxygen transport.