Week 6 Flashcards
FEB 27
Impacts of Climate Change to our Oceans
1
2
3
AKA “ “
4
1 Ocean Warming
2 Ocean Acidification
3 Anoxia (Eutropication) - not directly related to climate change
AKA The deadly trio
4 Sea level rise
3 - what is it
Anoxia - Eutropication
IS
1 nutrient load up (excessive nutr from fertilizers flushed into waterways) - N and Phosphor from agri and human sewage
2 Plants flourish (algae)
3 Algae blooms (oxygen is depleted - prevents sunlight from hitting other plants - plants die and O2 is further depleted
4 Decomposition further depletes oxygen
5 Death of the ecosystem - oxygen levels reach a point where no life is possible
1
Oceans are getting warmer since around 1950
Impacts of ocean warming
1
2
3
EX:
–> “Cold Blob” - north atlantic - we think it is due to the slow down of the thermohalinecirulation
1 impacts many kinds of sea life
(changes migration and breeding patterns)
(changes species composition)
2 Affects ocean and atmospheric circulation (weather patterns)
3 Causes more powerful tropical storms
EX: coral bleaching
- corals live in a mutually exclusive beneficial relationship (or symbiosis) with small algae - algae feed via photosynthesis the coral while coral provides shelter and nutr to algae
Algae are sensitive to warmer water - algae are expelled - results in coral bleaching or death
2
Ocean Acidification
Ocean Acidification (related to the driver of climate change) - nothing to do with warmer - has to do with the increase of GHGs (CO2)
All waters on the planet are an equilibrium with the gases that they come in contact with - so we get dissolved oxygen in water, Co2
Based on graph - decreases begin around early 2000s
* increase in acidity means decrease in pH
IPCC says:
THE PROBLEM:
–> Why do we care about pteropods? - marine calcifiers - its a food web issue: these organisms form the basics of the food web “the potato chips of the sea” - cause everything eats them
Corals also need carbonate to build their shells
ALSO polar systems
… colder water more readily absorbs CO2; therefore acidification may be happening faster here
IPCC: ocean acidification will continue to increase in the 21st century (AR6) - virtually certain
PROBLEM:
Organisms generally have a narrow range of conditions under which they thrive
(temperature, nutrients, pH)
pH particularly important for - marine calcifiers : marine organisms that take carbonate and build calcium carbonate shells (Diatoms, crabs, oysters, clams, muscles (crustaceans) —- very very susceptible to pH changes
REASON: when CO2 dissolves in water - it immediate forms carbonic acid - acids dissociate in water so break into hydrogen ions (where acidity comes from) & into bicarbonate and carbonate
Building blocks of their shells are Calcium and Carbonate
WHEN we increase CO2: increase CO2 dissolved which increases carbonic acid (but this decreases carbonate ions and more bicarbonate ions
Calcifiers get stressed because there isn’t enough Carbonate to build their shells - super high pH - shells dissolve
4 Sea Level Rise
How do we measure it?
1
2
WHY is sea level rising?
*
How do we measure it?
2 most important
[1] tidal gauges - pole with markings - very local - always relative to local land surface (problem: land can move up and down) (rebound from glaciers)
[2] Satellite Altimetry: sea level rise is measured with the satellite, so it measures the distance to the center of the earth, then it measures the distance to the sea - takes the difference and comes up with sea level - much more accurate
WHY?
* melting ice & snow on land ONLY ** exam - glacials and ice sheets (not precipitation - as it is apart of the water cycle that is already there)
Not sea ice because it is already floating in the ocean (ex. Water glass filled with water and ice cubes to the top - when ice cubes melt - glass doesn’t over flow)
→ as water gets warmer (thermal expansion) i.e water expand as it warms
( accounts for 30-55% of 21st century global mean sea level rise (IPCC) )
CRYOSPHERE
MARCH 1
The Greenland ice sheet
2nd largest body of ice
Ice occupies over 40% of the island - 2km deep - 110,000 years old
–> It is…
Glacier =
Calving Front =
–> Slowly melting
- loss of 50-100 gigatons / year between 93 - 2003
= Glacier = body of very dense ice that is moving on land [Jakobshavn or Illulisat] glacier retreat
Calving Front = Calving is the process by glaciers lose mass - where the melting is occurring
Antarctic Ice Sheet
almost 90% of earths ice mass is in Antarctica - temps as low as -90 cels
3 important regions
1,2,3
[1]
[2]
[3]
[1] Antarctic Peninsula
[2] West antarctic piece
[3] East antarctic piece
- Ice shelves are associated around the ice sheets
Ice Shelf = permanent floating sheets of ice that connect to a landmass - act as a plug (hold back the ice on the land)- loss of ice shelves allows glaciers and ice sheets to flow more quickly to sea - contributes indirectly to sea level rise
[1] 4% of the ice
- showing signif effecs of global warming
- since 74 gradual decline in ice shelf volume - Larsen B Ice shelf collapse
[2] 13% of ice
- Recent studies - sheet is particularly unstable and could collapse within the next 100 years
[collapse could lead to a sea level rise of nearly 3 meters, which would engulf major US cities (NYC, Miami)
[3] 83% of antarctic ice
- very thick - 30 mil years old
- more stable and not particularly threatened
Impacts of Sea Level Rise on Coastal communities
CANADA - projected relative sea-level rise change along canadian coastlines at the end of the century (using RCP 8.5)
Hudson’s bay: negative values - as hudson’s bay is still rebounding from glacier cover in previous centuries
**Atlantic CAN: Large sea-level change here - much more vulnerable to sea-level change, difference in how lands are moving in the two coasts, more so at sea level whereas BC is more mountainous
From Canada’s Changing Climate Report, 2019
–>
–> Freq and magnitude of extreme high water level events will increase (high confidence)
Will result in increase flooding
[infrastructure and ecosystem damage as well as coastline erosion]
Expected to become larger and occur more often - as a result of declining sea ice cover
[leading to increased wave action and larger storm surges (high confidence)
Storm Surge =
SIDS =
= The unusual rise of water caused by high winds during a storm
Causes dangerous flooding and can go far inland
SIDS = Small Island Developing States
→ Low-lying coastal countries with sustainable development challenges- Sm populations, limited resources, remoteness, susceptibility to natural disasters, fragile environments etc.
[namely Caribbean and Pacific island chains]
[Denmark - struggling as most their land mass is under water - but they are wealthy and good engineering]
Impacts on Natural Ecosystems
FIRST - how do we study the impacts of CC on natural ecosystems?
1
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–>
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2
–>
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3
1 Observation Methods- Observations over time
Observation along environmental gradients (changes in ecology up mountain sides - warmer bottom, colder top)
–> Phenological Studies:
Phenology = the study of periodic plant and animal life cycle events and how these are influenced by climate variations (seasonal, annual)
- Bud formation, flowering, migration
- Observe patterns of change over a long period of time and correlate to climate change (temperature) [remember correlation doesn’t -equal causation]
–> Palaeoecological methods
‘Reconstruction’ of ecosystems
- Recall climate reconstruction exs
- Analysis of lake sediments for pollen
- Dendroclimatology
- Historical accounts by explorers, settlers etc.
2 Experimental Methods
Manipulating climate drivers (temp and precipitation)
–> Manipulation of temp/precip/Co2 conc
- measure some kind of impact - can examine impacts to projected climate changes
- CO2 manipulation
Growth Chambers: benefits - good control variables ; limitations - lack external validity
OUTDOOR chambers: open topped is best - benefits: more external validity; limits: “chamber effects increase temp and humidity
–> Free Air CO2 Enrichment (FACE) experiments
- no chamber walls, exs; benefits: much higher external validity; limits: long-term funding and large quantities of CO2
3 Theoretical/Statistical Methods
Ecosystem models (analytical or stimulation)
