Urgency Flashcards
The Cryosphere
- Where ‘permanent’ snow and ice is possible
- Majority near poles
- 2 great continental scale glaciers:
Greenland, Antarctica
Ice sheets
Covers a landmass
Ice shelves
Fixed to land but over a sea
Antarctica has many
Increasing instability of shelves
Iceberg size of London breaks off Antarctica
7.5 tonnes since 1997
East Antarctica climate change
Only major land area without clear evidence of warming over past ~50 years
(intensifying winds, more storms and snow)
West Antarctica climate change
Significant warming, and major ‘break up events’ of several ice shelves
Antarctica
- 90% of world ice and millions of years accumulated ice melting very quickly
- Rapid biological changes
Sea Ice
- Expands in the winter
- Contracts in the summer
- Melting of sea ice don’t not contribute to global water levels
- Sea level rises from sheets and ice fall into the sea
- Warm water expands more then cold water
- Freezing later in year
- Polar bear and Walrus affected by lack of sea ice
Permafrost
- Permanently frozen layer of mostly soil, gravel and sand, bound together by ice
- Contains more carbon than atmosphere
- With thawing, communities of microbes emerge and decompose long-frozen organic matter
- CO2 + Methane
- Canada Permafrost retreat 130km in 50 years
2 great continental-scale glaciers
- ## Antarctica + Greenland
If all melts
- Antarctica 58 m sea level rise (centuries away)
- Greenland 7 m sea level rise
Last time earth 4C warmer
no ice at either pole and sea level >70 m higher
Glacier loss on Kilimanjaro
1912-2008: 85% decline in ice cover + acceleration 1990→
Perito Moreno Glacier (advancing across Argentino Lake)
- Rare exception: glacier increased in mass
- Uncertainty why winter accumulation of ice and snow greater than summer melt
annual ‘pulse’
- Acts as the engine of deep ocean currents
- Dense cold salty water from sea ice formation
Ocean Currents
- Most volume in deep slow current
- Surface movement is different
- Transfers heat around Earth
- Ex. Gulf Stream
Eastern Africa: Kilimanjaro glacier
- 1912-2008: 85% decline in ice cover
+ acceleration 1990→
South America:
Bolivia + Argentina
- Bolivia 2nd largest lake dries up
- Perito Moreno Glacier (Argentino Lake)
- glacier increased in mass
- Uncertainty why winter accumulation of ice and snow greater than summer melt
North America:
Alaska + Montana
- Alaska seeing very fast glacier melting
- Montana (Glacier N.P.)
- 1850 = 150 glaciers
- 26 remain
Asia: Nepal
- Everest has seen fast decline in its glaciers
Europe: Alps
- Alps glaciers will be 2/3 melted by 2100
- Skiing on decline
Jeremy Jones
- Snowboarder
- President of “Protect Our Winters”
- Climate education
Deforestation Double Whammy
- One time burst of CO2
- Reduced C sequestration
Tropical rainforests
~6% of land; ~50% of plant & animal species
- ¼ of carbon absorbed by world’s forests
- 1-2% decrease yearly
Amazonia
- regional average rainfall ~2 m/yr
- ½ is from the Atlantic ocean via trade winds
- ½ is ‘recycled’ from forest
- Western Amazonia: up to ¾
Amazonia tipping point
- less evaporation
- drier (more fires)
- point of no return 1-2 decades
- warming above global average
temperate deforestation
- increase in wildfire and severity
- total wildfires in US burned twice as much land/year in 2010s as in 1970s
- positive feedback: more wildfires more CO2 emissions from major carbon sink to atmosphere
- more warming
Australia
- tropical and temperate forests
- hot and dry conditions limiting ability to use hazard reduction burns
Peatlands
- northern peatlands contain ~15-20% of all terrestrial biological carbon
- most northern peatlands are small sinks for atmospheric CO2 and small to significant sources of atmospheric methane
- hotter and drier conditions threaten sink function
Coral Reefs
- Warming slower than land
- Rainforests of ocean
- 14% decrease in decade
- 3/4 reefs at severe risk
- 1/4 ocean species use reefs at some point
algae (zooxanthellae)
- Photosynthesis gives color
- Foundation of food web
Coral Polyps
Tiny animals that can live in huge colonies
coral ‘bleaching’
- thermal stress or pollution (algae, whitening)
- effectively starves food web + heightened disease risk
- survivable: initially at risk, not necessarily dead
- destabilizes whole food web
Acidification
- additional CO2 absorbed is changing the chemistry of the ocean (increasing carbonic acid)
- pH = ~30% lower than pre-Industrial level
- threatens plankton
- reduces calcium carbonate
calcium carbonite
key physiological ‘building block’ for skeletal and shell construction for a range of marine organisms
- (e.g. coral, oysters, clams)
Some uncertainties on acidification
- Precisely when rising level of carbonic acid corrodes shells and there will be too few carbonite ions for shell and skeletal growth
- when does rate of ocean warming drive major decline in dissolved CO2 intake?
Some warming + sea level rise will continue even if all emissions massively reduced tomorrow Key Reasons
- momentum from positive feedbacks
- ‘thermal lag’
- ‘sluggish’ but ‘battery effect’
- CO2 emitted into atmosphere 100 year residence time
Battery Effect
capable of absorbing and releasing a much larger quantity of heat than land
What is a safe level of warming
- 1.5 C political target 2015
- If the world does nothing, heading to average projections of 2-4 (more around 3)
- ## Way to hot to deem safe
Too make the 1.5 max average warming
- Radically and rapidly change emissions
- Only attainable for huge cuts
- 350 ppm in atmosphere of CO2
- Today is 420
- Current course for 500 by 2050
Last time ppm CO2 was 500
- Surface temps of 5 warmer
- Sea level of 40 M higher
Cambrian Explosion Extinction
5 mass extinction events or spasms in the fossil record
Background rate extinction
very slow pace of species evolving and dying off
Spasm extinction
large % of species die off over relatively short period
6th Extinction spasm
“Virtually all students of the extinction process agree that biological diversity is in
the midst of its 6th great crisis, this time precipitated entirely by man [sic].”
