APES Unit 9 Flashcards
cause of ocean acidification
incr. CO2 in atm. leads to incr. ocean CO2 through direct exchange.
CO combines with ocean water to form carbonic acid H2CO3
carbonic acid and dissociates formula
CO2 + H2O –> H2CO3 which can break into HCO3- , and H+ + CO32- (carbonate already in ocean) which forms HCO3-
how can ocean acidification damage marine organisms
they make shells using calcium (Ca+) and carbonate (CO3 2-). makes carbonate less available and causes marine shells to breakdown.
weaker shells
anthropogenic cause of ocean acidification
fossil fuel combustion
deforestation
coal/gas combustion
UV-C, UV-B UV-A radiation
UV-C is 100% absorbed by ozone in stratosphere. 90% of UV-B and 50% of UV-A
without ozone layer life
would be non-existant because radiation damages tissue and mutates DNA.
human health benefits of ozone layer
prevents skin cancer and cataracts
how ozone absorbs UV-B and UV-C
UV-C radiation breaks down O2 into O and O
– when O reacts with O2, O3 is formed
– UV-C and UV-B can reverse this process by breaking O3 into O2 and O
continued formation and breakdown of O3 in stratosphere absorbs all UV-C and much of UV-B radiation
anthropogenic ozone depletion
CFCs are primary anthropogenic cause of O3 breakdown
– UV radiation causes free chlorine atom to separate from CFCs
– chlorine atom bonds with one of O from O3 (ClO and O2)
– free O will steal O from ClO leaving Chlorine to go breakdown more O3
one chlorine atom can damage the whole ozone layer
one Cl atom can persist in atm. for 50 - 100 yrs. and can destroy upto 100,000 O3 atoms
natural ozone depletion
antarctic winter forms polar stratospheric clouds (PSC)
clouds made of ice crystals trap chlorine compounds
in antarctic spring, PSCs begin melting and release Cl compounds
what is main way to reduce anthropogenic O3 depletion
phasing out and replacing CFCs
montreal protocol
global agreement to phase CFCs our of production
what were CFCs replaced with
replaced with HCFCs, which still deplete O3 and are GHG but less
(not permanent solution but temporary transition option)
Replacement for HCFCs is HFCs, still GHG but not O3 depleting
current slow transition to HFOs, not GHG, not O3 depleting
CFC
chlorofluorocarbon
HCFC
hydro-chlorofluorocarbon
HCF
hydro-fluorocarbon
HFO
hydro-fluoroolefin
the greenhouse effect
(positive of greenhouse effect)
gases in earth’s atm. trap heat from the sun and radiate it back down to earth
+ without greenhouse effect, earth would be too cold to support life
major gasses and sources
CO2 - fossil fuel combustion, decomposition, deforestation
CH4 - nat. gas extraction and combustion, animal agr., anaerobic decomposition
N2O - agr. soils (denitrification of nitrate)
CFCs/HCFCs/HCFs - refrigerants, propellants in aerosol products
water vapor - evaporation and transpiration
water vapor as a GHG
technically GHG; does not contribute to global warming but can have a reinforcing effect
– stays in atm. for much shorter time, only about 9 days
GWP (global warming potential
measure of how much gasses can contribute to global warming over 100 yrs. relative to CO2
GWP depends on
1) residents time
2) infrared absorption (heat)
GWP of different GHGs
CO2 has 1 (since they are relative to CO2)
CH4 is 25-28 times more potent than CO2
N2O is 300
CFCs… is 1,600 - 13,000
why are sea levels rising?
thermal expansion
melting of polar and glacial ice
thermal expansion
water molecules move slightly further apart when heated
– all the water molecules of ocean moving slightly apart leads to sea level rising
melting of polar and glacial ice
-incr. GHGs lead to a warmer climate and more melting or ice sheets
– this water flows into the ocean and leads to sea level rise
flooding of coastal ecosystems like estuaries
loss of species that depend on arctic and tundra ecosystems (polar bears, penguins, reindeer)
human impacts and relocation of coastal human pop.
-incr in flood frequency = higher insurance and repair cost
- saltwater intrusion
- humans forced to move inland
atmospheric and ocean warming
as the atm. warms due to GHGs, heat is transferred to the ocean
– ocean absorbs heat radiated back to earth by GHGs
thermohaline circulation and warmer ocean waters
distributes heat asborbed at surface to depths and other areas of earth
-heat absorbed by ocean can transfer back to atm. for decades
effects on marine ecosystems of warmer waters
– migratory routes and mating seasons can be altered, esp. for whales
– reproductive timing often tied to temp change,
– habitat loss: coral bleeching leads to loss of reef habitat; shallow, sunny waters ideal for algae and coral become to deep
– toxic algae blooms: toxic blue green algae prefer warmer waters and warm temp.
historic climate change due
due to variations in earth’s orbit around the sun
eccentricity
every 100,000yrs. bringing it closer to and further from the sun
more eccentric = further from sun
obliquity
every 40,000yrs. exposing northern lattitudes to higher insulation at diff. times
= more extreme tilt = more extreme seasons
milankovitch cycles
predictable variation in Earth’s climate. these historic climate changes
how to meassure ancient CO2 concentrations
(levels of CO2 concentration, historic and now)
ice cores.
scientists can dig upto 800,000 yrs ago
up to then CO2 levels have never exceeded 300 ppm but after 1950, concentrations have sharply increased to their current level of over 400ppm
effects of climate change
rising temps: habitat/species loss, drought, incr. fires, more intense storms
rising sea levels
melting of permafrost
displacement of coastal communities
melting of permafrost
permanently frozen tundra soils that begin to thaw and release methane and CO2 from decomposition
widening and weakening of hadley cells
(shifting zones)
as temp. difference between equator and poles decr.,[air descending and expanding from equator travels furhter before sinking]
[–this shifts subtropical zones toward poles and expands tropics]
destabilizing jet stream
(what drives polar jet stream)
(effect of less diff)
[temp. and pressure diff between polar and subtropical regions drives polar jet stream]
[less diff in those leads to wobblier jet stream]
suppresion of thermohaline circulation
[ice melt from greenland = buildup of cold freshwater in N atlantic]
freshwater is less dense than salt water [preventing it from sinking]
arctic sea ice loss = habitat loss for
seals use it for resting and breathing holes
algae grow on ice froming base of arctic food web
polar bears use ice for hunting and breathing holes
altered range of marine ecosystems
new marine habitat will be created bc flooding coastline
some areas of ocean too deep to recieve sunlight
