4.4 climate change Flashcards
what is a greenhouse gas
a gas that absorbs longwave radiation, trapping it in the earths atmosphere
when radiation hits the earth, its radiated back as __________ radiation
longwave radiation
(From sun = shortwave)
2 gases that contribute most to greenhosue effect
water vapour and co2
how does water vapour accumulate in the atmosphere?
evaporation from ocean surface + transpiration
how does co2 accumulate in the atmosphere
living organisms respire
organic matter / fossil fuels are burned
2 other greenhouse gases that contribute to greenhouse effect
methane
nitrous oxides
2 sources of methane
methanogenic bacteria — archaeans when the break down organic waste
coal mining – methane deposits released
3 sources of nitrous oxides
fossil fuel combustion
agriculture
activity of some types of bacteria
name the 2 factors affecting the impact of a greenhouse gas
- ability to absorb longwave radiation
- concentration in atmosphere
how does ability to absorb radiation and concentration in atmos of METHANE affect its impact
strong ability to absorb radiation
BUT relatively low atmospheric concentration
2 things that atmospheric concetration of a greenhouse gas depends on
- balance between RELEASE and REMOVAL of that gas from the atmosphere
eg CO2 - length of time gas is present in atmosphere
methane vs water vapour length of time present in atmospher e
methane: remains 10-12 years before being oxidised
water vapour: most abundant gas BUT only 9 days
in what part of the spectrum is the radiation radiated back to the atmosphere by the earth
infra-red – longer wavelength
percentage of radiation absorbed by atmosphere on the way:
1. in
2. out
- 25%
- 85%
impacts of increase in global temps: climate change 3
incr temp = incr water evaporation
= heavier rainfall
affects wind and ocean currents
= stronger hurricanes and typhoons
rising sea levels
impact of warming climates on animals
loss of habitat – coastal, ice
changes to migratory patterns: artic areas warmer = competition
incr decomposition bc melting permafrost = exposes saphotropic bacteria to oxygen, releasing methane
co2 levels have risen to record highs since the __________ ___________
industrial revolution
why did the industrial revolution result in so much co2
increased use of fossil fuels: transport, electricity, heating
clearing and burning of forested land
what is earths main carbon sink
oceans !
thats why co2 levels are lower than what would be expected after the industrial revolution
impact of more co2 absorbed in the oceans
ocean acidification = threathens habitat eg corals
how does heavier rainfall lead to acid rain
more GH gases dissolve into rainwater = falls into land, rivers, lakes, oceans as acid rain
process of ocean acidification 3
- incr CO2 dissolves in water, becoming carbonic acid
- dissociates to become H+ ions
- decr in pH
effect of decr pH on CaCO3
decr pH = incr solubility of calcium carbonate = decr amt available for organisms
why is calcium carbonate importnat in oceans
used by marine organisms (crustaceans, molluscs, corals) to build exoskeletons and shells. – calcification
what is calcification?
the process by which some marine organisms use calcium carbonate to build their exoskeletons and shells
impact of decr CaCO3 thats readily available in oceans on CORALs
slower building of coral reefs + more brittle
exoskeleton dissolve = less resilient to other factors
what aspect of coral function is affected by ocean acidification
ability to re-colonise and grow stable structures
they are SENSITIVE to temp changes!!!
define the precautionary principle (burden of proof)
even without concrete evidence of a casual r/s, precautionary measures should be taken
to ensure humans arent causing harm to envt
