C13 - History of Earth's atmoshpere Flashcards
when did the earth form
4.6 billion yrs ago
how did the early atmosphere form
volanic activity
theory of early atmosphere formation
-volcanoes released co2, water vapour, nitrogen
how did oceans form
watre vapour condensed as Earths temp cools
-fell as rain
-collecting in hollows of the crust
-icy comets rained down on Earth = melted
gases in early atmosphere
mainly co2
-h2o
n2
methane and ammonia
no o2
when did life begin
3.4 billion yrs ago
how did first organisms live
used breakdown of chemicals as energy
what happened 2.7 bn yrs ago
-algae used enegry from sun to photosynthesis
-producing o2 as a waste product
how did o2 levels rise
growth of algae/bacteria in oceans thrived
-released o2 as a waste product
-plants populated Earth
why did early microorganisms die out
as o2 levels rose
-couldn’t tolerate rich o2 atmosphere as they weren’t used to it
carbon ‘locked in’ rock
co2 in photosynthesis is converted to glucosed = plant structure
-as animals consume plants converted into body/bones
-skeletons of marine life built up at bottom ocean
-covered w layers of sediment
-extreme pressure = sedimentary rock
limestone
contains mainly calcium carbonate
-sedimentary rocks
formation of fossil fuels,
-remains of ancient organisms
-crushed by large scale movements of earth
-heated within earth’s crust over long time
coal formation
-sedimentary rock
-formed by plants dying in swamps
-in absence of o2 and being compressed
crude oil/ natural gas formation
-formation from plankton in muds/ seadbeds
-covered by sediment/ compressed
-trapped beneath layers of rocks
how was co2 removed from early atmosphere
-by dissolving in oceans
-reacted w metal oxide + precipitate fell to seabeds
ammonia + methane removed early atmosphere
-reacted w o2 from photosynthesis
nitrogen build up in atmosphere
-unreactive gas so it stayed
today gas composition
78% = nitrogen
21% = o2
argon = 0.9%
co2 = 0.04%
greenhouse gases
absorb energy radiated from earth’s surface
greenhouse effect
-earth is heated by the sun
-30% is reflected back to space
-earths emits longer wavelength infrared to cool
-ghg absorb infrared
-trapped radiation = heats molecules + raises temp
ghg allow what
short - wavenlength (UV) to pass through
higher ghg proportion=
more infrared absorbed
increase of co2 due to
combustion of fossil fuels
- electricity
increase of methane is due to
-grazing cattle
-rice farms
-decomposing waste
-more landfills
co2 sinks
tropical rainforests
oceans
oceans as a co2 sink decreasing
-temps rise
-co2 is less soluble so less effective
rainforests as co2 sinks decreasing
deforestation
-less co2 removed as photosynthesis is reduced
increased ghg from humans
increase global temps
ice caps drilled from greenlands ice sheets shows
-gas trapped inside
-analysis of air shows change
-most co2 than past 440 000 yrs
rising sealevels due to
-melting ice caps
-expansion of warmer oceans
rising sea levels means
-flooding
-islands disappear
-coastal erosion
impacts of climate change
rising sealevels
-more frequent/severe weather storms
changes in temp + rainfall
affect food production
dry lands will get drier
-monsoons = heavier
-extinction of species
carbon footprint of an event/ product
-total amount ghg emitted over its full life cycle
carbon capture and storage
-pump co2 produced deep underground
-absorbed by porous rocks
carbon capture con
increases cost of electricity by 10%
how to reduce methane from cattle
less demand for beef
-plant based diets instead helps agricultural land be used more effectively
reduction of fossil fuel use
taxing consumption
biofuels
-made from plant material that absorbs co2 during photosynthesis
-returns co2 when burned
-carbon neutral
sulfur from fossil fuels
-sulfur reacts w o2 - sulfur dioxide
sulfur dioxide
-acidic toxic gas
-causes acid rain
-damages trees/marine life
-attacks buildings made from limestone
remove sulfur
-remove before burnt
-either in petrol or gas fired power stations
removing sulfur dioxide in gas power station
-removed from waste/ flue gases be reacting with calcium oxide/hydroxide
not enough o2 in engine
-incomplete combustion occurs
incomplete combustion
-co formed
-toxic gas
-odourless and colourless
why is co toxic
binds to haemoglobin instead of o2
starves body of o2
symptoms of drowsiness
nitrogen oxide
-high temps in engines cause unreactive nitrogen to react with o2
-toxic and triggers asthma
-acid rain
diesel engines
-burn larger molecule hydrocarbons
-don’t burn fully
-releases particulates
particulates
tiny solid particles of carbon + unburnt hydrocarbons in air
-travel to upper atmosphere
-refelect sunlight into space = global dimming effect
-causes cancer
