week 12-tay Flashcards
weather
short-term state of the atmosphere
- can change within minutes or hours
- influences what clothes you wear on a given day
climate change
long-term pattern of weather
- average weather other many years in one specific place
- where you live influences the entire wardrobe you buy
pre-human causes of climate change
- solar cycles
- changes to earth’s orbit, tilt, precession
- plate tectonics (continent location)
- volcanic activity
- land cover changes
- ocean currents
- meteorites
- concentration of GHG
land cover changes
refers to forests and fungi
- effect carbon cycle
what is the atmosphere?
region surrounding the Earth comprised of gases and particles bound to the Earth by its gravitational force
atmospheric composition (main chemical species)
- oxygen (78%)
- nitrogen (20%)
- argon (0.9%)
- water vapour (0-4%)
water vapour
highly variable
- H20
layers of the atmosphere
- troposphere
- stratosphere
- mesosphere
- thermosphere
the troposphere
where the vast majority of our weather occurs
cumulonimbus cloud
gives us a well-mixed troposphere
why is the stratosphere so warm?
the ozone layer lies within the stratosphere
- the ozone layer interacts (absorbed) with UV radiation - heating up the stratosphere
thermosphere
should be hottest up here because it is closest to the sun BUT it is not because there isn’t much matter to hold the temperature
- temperature is relative - cannot have temperature without matter to hold it
tropopause
separates the troposphere and stratosphere
stratopause
separates the stratosphere and mesosphere
mesopause
separates the mesosphere and thermosphere
earths energy budget
incoming and out-going radiation of the earth
- radiation from the sun heats up the Earth, but the sun has more heat than the sun needs to the rest is reflected in atmosphere
what would happen if the earth had no atmosphere?
we would have a planet extremely warm during the day and extremely cold at night
example of a plant with no atmosphere
mercury
- 450 degrees during day (everything burns)
- -250 degrees at night (everything freezes)
intensity of radiation
hot objects radiate higher radiation than cooler objects
- radiation from the sun is shorter wavelength, higher intensity energy
- radiation from the Earth is longer wavelength, lower intensity energy
what can we not control in the atmosphere that we have a set amount of?
water vapour
what does climate change do to Earth’s energy budget?
unbalances the incoming and out-going radiation of the Earth
human generated GHG
- CO2
- methane
- nitrous oxide
- tropospheric ozone
- chlorofluorocrbons
- hydrochlorofluococarbons
- hydrofluorocarbons
potent GHG
hydrochlorofluococarbons and hydrofluorocarbons
potent
how much energy they trap
carbon dioxide contribution to GHG effect
58%
methane contribution to GHG effect
15%
nitrous oxide contribution to GHG effect
5.9%
tropospheric ozone contribution to GHG effect
12%
chlorofluorocarbons contribution to GHG effect
7%
hydrochlorofluorocarbons contribution to GHG effect
1.7%
hydrofluorocarbons contribution to GHG effect
0.4%
what two atmospheric gases had the largest change?
CO2 and methane (largest)
what atmospheric gases contain lots of GHG but are not abundant?
- chlorofluorocarbons
- hydrochlorofluorocarbons
- hydrofluorocarbons
what is the number one GHG?
CO2
- not the worst one, but most abundant
cumulative fossil fuel CO2 emissions into the atmosphere
- 46% from coal
- 35% from oil
- 14% natural gas
- 3% decomposition or carbonates
- 1% from flaring
fossil fuels
not in a carbon neutral cycle
- damaging
CO2 emissions and atmospheric CO2 relationship
as CO2 emissions increase, atmospheric CO2 increases
CO2 emissions, atmospheric CO2, and global temperature relationship
global temperature rises as CO2 emissions and atmospheric CO2 increase
methane concentration from 1985 to 2025
constant increase
why do CO2 and CH4 concentrations cycle annually?
changing of seasons
summer and CO2 and CH4 concentrations
CO2 and CH4 concentration decrease
- earth takes it in (plants and oceans)
winter and CO2 and CH4 concentrations
CO2 and CH4 concentration increase
annual CO2 cycle
winter- increase CO2 concentration
summer- decreased CO2 concentration (plants and oceans take it all in)
ice cores
CO2 and CH4 were trapped in-trapped in the ice (air bubbles)
proxy
indirect measures used to infer information about environmental conditions or processes that are difficult or impossible to directly observe
ex. tree rings, ice cores
when do proxies work?
- when spatial biases are taken into account (they impact conclusions)
- more proxies, better statistics = improve estimations
- proxies require using the statistics properly
is climate change due to solar cycles (the sun)
NO
- since 1970 global temperatures have risen, and solar irradiance has plateaued
eccentricity of Earth’s orbit
varies near circular to ellipsoid (100,000 yr cycle)
Earth’s obliquity (tilt)
varies from 22 to 24.5 degrees
- larger angle = warmer conditions (41,000 yr cycle)
Earths precession
what season the Earth is in during aphelion and perihelion (23,000 yr cycle)
- perihelion during SH summer
aphelion
Earth is furthest away from sun
perihelion
Earth is closer to the sun
Earths cycles (orbit, tilt, precession)
cycles are like waves
- can work constructively and destructively
- called Milankovitch cyles - by Milutin Milankowitch
Milankovitch cycles
produced the ice ages
is climate change due to Earth’s orbit (Milankovitch cycles)
NO
- current stages of cycles are not indicative of excessive warming
- we should be going into an ice age according to these cycles - but we are not - temperatures are rising
is climate change caused by volcanoes?
NO
- fossil fuels emissions vastly outweigh volcanic emissions
- at least 130x greater than volcanic
what drives climate change?
HUMANS
- temperatures rose “rapidly” after ice ages end (5 degrees in 5000 yrs)
- in 20th century temperatures rose 0.7 degrees in 100 yrs
- since 1970, temperatures are rising 0.2 degrees per decade
land surface temperatures now
moving away from where we were
- 4-5 standard deviations away from the mean
sea surface temperatures now
6 + standard deviations away from the mean
- moving away fastly
southern hemisphere (Antarctica) sea ice extent
very low levels of sea ice now
Representative Concentration Pathway (RCP) 7
baseline
- nobody does anything about climate change
positive feedback loops
cause run-away change (amplification)
- effects produce more change in the same direction
- not a good thing = feeds on itself and increases in amplitude
negative feedback loops
result in stability/equilibrium (dampening)
- effects produce change in the opposite direction
- bring things back to equilibrium
positive feedback and climate change
- increasing temperatures
- less sea ice
- darker sea surface
- sea surface absorbs more heat
***goes back and continues to increase temperature
negative feedback and climate change
- elevated CO2
- more plant growth (fertilization)
- increased extraction of CO2 from the atmosphere
how are oceans the greatest ally for climate change?
when oceans warm up, they lose their capacity to take in (absorb) CO2, therefore it must release it back into the atmosphere
how much carbon emitted to the atmosphere does the ocean abdorb?
31%
how much heat generated by emissions in absorbed by the oceans?
90%
- heats up and loses capacity to absorb gases - contributing to climate change (increase atmospheric gases)
how does increasing CO2 in the oceans affect ocean chemistry?
- decreases pH of the ocean
- significant and harmful consequence of excess CO2 in the atmosphere
pH scale
used to specify the acidity or basicity of an aqueous solution
acidity
concentration of hydrogen ions in the solution
pH and acidity
increase concentration of hydrogen ions, pH decreases
pH and sea water since industrial revolution
surface ocean has decreased by 0.1-0.15 pH units
- corresponds to a 30% increase in hydrogen ion concentration
buffering
minimizes of dampens changes in pH
ocean acidification
- atmospheric CO2 enters the ocean and undergoes chemical reactions
- dissolved CO2 + H20 = carbonic acid
- creates bicarbonate and hydrogen ions
- bicarbonate creates carbonate ions
calcite compensation depth (CCD)
as calcium carbonate shells sink and dissolve below CCD, carbonate ions are released, which buffers the oceans pH
- CCD has risen by 3.6% in last 200 years
purpose of buffering in the ocean
prevent seawater from experiencing large changes in pH
what happens if seawater is too alkaline/basic?
chemical reactions release hydrogen ions into seawater, which lowers pH
what happens if seawater is too acidic?
chemical reactions run in reverse, removing hydrogen ions from seawater and causing pH to rise
carbonate ions and ocean acidification
- carbonate ions are consumed in reverse reaction with free hydrogen ions to buffer pH
- adding more CO2 consumes more carbonate ions (hinders the capacity of calcifying organisms to produce shells)
effect of ocean acidification (increased acidity)
- higher concentration of atmospheric CO2
- fewer carbonate ions
- fewer, smaller, marine calcifiers
effect of ocean acidification on organisms
- difficult for organisms (calcifiers) to create hard parts (less carbonate available)
- makes process more energy intensive
- smaller, more fragile, dissolving shells
- possible factor in low reproductive rates in oysters (inhibit larval oysters from developing their shells)
effect of ocean acidification on mussels
- byssal threads- become weaker
- mussel beds are protective homes for other species - but when weaker they are not
- food security- mussels are an important source of nutrition
- for economy -mussel farms have inability to grow (%1.5 billion industry)
pteropods
sea butterfly, sea angel
- major zooplankton components in oceans at high latitudes
- experiments under ocean pH projections show decreased viability (living)
major effects of ocean acidification
- loss of biodiversity
- potentially affect food security
- $$ loss (aquaculture, tourism)
- loss of coastal protection
- decrease in ocean’s capacity to absorb CO2
effects of ocean acidification on finfish (tuna, sardines, halibut, etc.)
loss of habitat and food supply
- possibly some effects on behaviour, fitness and larval survival
effects of ocean acidification on crustaceans (shrimps, crabs, lobsters, etc.)
relatively resistant to changes in ocean pH
effects of ocean acidification on corals
minus 32% calcification and minus 47% abundance
effects of ocean acidification on echinoderms (sea urchins, sea cucumbers, starfish)
minus 10% growth and minus 11% development
effects of ocean acidification on molluscs (clams, scallops, oysters, cephalopods - squid, octopus, etc.)
minus 40% calcification and minus 34% survival
effects of ocean acidification on calcifying algae
minus 80% abundance
effects of ocean acidification on diatoms and fleshy algae
positive growth
ocean warming
90% of excess heat generated from fossil fuel emissions is absorbed by oceans
- mean global ocean temperatures and heat are rising (mostly ocean surfaces)
sea level rise (ocean warming)
3.4 mm/yr
- at this rate, by 2100, sea levels will be 36.4 cm above 1993 levels
how does sea level rise happen?
- melting land surface ice (glaciers)
- thermal expansion of warming water (thermostatic) - temperature increases, density decreases
- isostatic changes can have a small impact (more locally)
- melting sea ice has little impact on sea levels
impacts of sea level rise
many Pacific Island Nations are at high risk os losing vast areas of their territory
ex. Kiribati, Solomon Islands, Fiji, Tonga, etc.
what percent of the worlds population lives along coastline (within 100km)
34%
when are impacts of sea level rise felt for those living along coastline?
during extreme events (storms, floods)
- not by sea level increasing by a few mm per day
average elevation of Florida
31 m
average elevation of the everglades
6 m
coastal erosion due to seal level rise
increasing due to climate change
- wave erosion (especially during storms)
3 parts of longshore current/drift
- supply: rivers, cliff erosion
- storage and transport: along beaches
- removal: submarine canyons
longshort current/drift
- transport of sediment along coastline
- occur as part of a beach compartment
coastal erosion: beach starvation
beach starvation due to longshore currents can increase erosion
traditional coastal engineering method
involves hard stabilization of shorelines
- build structures parallel and perpendicular to coast
3 methods to stabilize shorelines
- “hard” parallel stabilization
- “hard” perpendicular stabilization
- “soft” stabilization
“hard” parallel stabilization
building structures parallel to coast
- shoreline armouring (sea walls)
aim of “hard” parallel stabilization
create and artificially “permanent” shoreline
features of “hard” parallel stabilization
- severely reduce (even eliminate) natural erosion-deposition processes
- ensure intense, direct wave energy (prone to failure - built with inherent lifespan)
- can have large impact on biological processes
“hard” perpendicular stabilization
building structures perpendicular to coast
- groynes, rock wall jetties
features of “hard” perpendicular stabilization
- endure less direct wave energy, create storage zones (less prone to failure)
- utilize rather than prevent natural erosion-deposition processes
- less impact on biological habitats (sediment remains)
groynes (sediment)
- sediment depletion (down current)
- sediment accumulation (up current)
what are groynes built from?
wood (fence-like) or concrete
“soft” stabilization
based on notion of supporting/utilizing the naturally dynamic nature of coastal areas
methods of “soft” stabilization
- plant/maintain existing vegetation (marram grass, conifers, mangroves)
- restore salt marshes
- managed retreat - we move away from the coastline
- beach nourishment
mangroves
decrease surge level at back of them but increase surge level at front of them
beach nourishment
adding sand back to starved beaches
“band-aid solution”
drawbacks of the beach nourishment
- costs
- how long sand will last
- where is sand coming from
- environmental costs
environmental threat of beach nourishment
loggerhead sea turtle habitat damage
is beach nourishment legal?
no
coral bleaching
stressed corals expel symbiont algae (zooxanthellae)
- cause corals to lose their vibrant colours and turn white due to stress
- if stressful conditions persist, coral die
what are the causes of coral bleaching?
- increase water temperature (climate change)
- extremely low tides causing exposure
- overexposure to sunlight
- pollution
recovery of the coral bleaching
some recent recovery in great barrier reef (bad 2016 and 2017 bleaching events)
- more robust/resilient to stresses than first anticipated
why is coral bleaching more robust than first anticipated?
change in species dynamics
- less coral diversity
- more fast growing less structural coral
