EOS 365 Part II Flashcards
Average fate of anthropogenic CO2 emissions
~50% - atmosphere
~25% - biosphere
~25% - ocean
ocean CO2 absorption
in future will become less absorptive; fertilizer effect will decrease; atmospheric CO2 will become a higher absorber
Venus atmosphere
insolation: 654 W/m^2
albedo: 0.67
net solar: 216 W/m^2
97 atm
96% CO2
477ºC
Earth atmosphere
insolation: 342 W/m^2
albedo: 0.37
net solar: 216 W/m^2
1 atm
0.04% CO2
15ºC
Mars atmosphere
insolation: 147 W/m^2
albedo: 0.17
net solar: 122 W/m^2
0.006 atm
95% CO2
-63ºC
why mars is so cold even though 95% CO2
atmosphere is too thin to trap heat
proxy records
stable isotope ratios don’t change through time
- CaCO3 of plankton
- 12CO2 of stomata
- palaeosols
different elements
determined by number of protons in nucleus
different isotopes
determined by number of neutrons in nucleus (with same number of protons)
some stable isotopes
11/12B (80/20%)
12/13C (99/1%)
16/17/17O (99.8/.04/.2%)
fractionation
chemical, biological, physical processes occur differently for each isotope
water fractionation
H2(18)O, H2(16)O
takes more energy to evaporate heavier water (18)O
heavier water condenses easier
ocean sediment isotope ratio
cold climate– build up ice on land– ocean enriched in H2(18)O– shells have larger 18O/16O– proxy for volume of land ice and deep ocean T
photosynthesis isotope ratio
plants prefer 12CO2– become depleted in 13C relative to atmosphere
if higher CO2 in atmosphere- plant remains have less 13C
CO2 weathering thermostat
self-regulating system
slowest acting part of C cycle
most important process for stabilizing planetary climate
stable (-) feedback loop acting on million year timescales
CO2 weathering thermostat steps
CO2 emitted from volcano– atmosphere build up– dissolves in rain water– creates carbonic acid– acidic rain water– warms climate, increases rainfall– increased chemical weathering of mafics– release Ca, Mg ions into ocean– ions react w/ CO2 in seawater to produce minerals, precipitate, remove CO2– removal cools, reduces acidity of rain, slows chemical weathering
Ca + Mg + CO2 in seawater
minerals: Calcite (CaCO3), manganite (MgCO3)
precipitate: limestone
Snowball Earth
750Ma- Marinoan 635Ma- Sturtian 0.94S breakup of supercontinent, Rodinia-- more shoreline-- more evaporation near land-- enhanced weathering and CO2 drawdown continents at mid latitudes
> weathering
> volcanism
> CO2 drawdown
initiating snowball cycle
breakup supercontinent– weathering > volcanism– polar ice caps grow equator ward– runaway feedback– total ice-cover– loss of bioproductivity– weathering < volcanism
terminate snowball cycle
continental ice sheets– weathering «_space;volcanism– rapid loss of ice cover– hothouse– strong weathering draw down CO2– rate slows w/ sea level rise– equilib restored
Phanerozoic
541Ma - Present
age of multicellular life and fossils; proxy data for CO2, not much for T
Cenozoic
65Ma - present
ocean T proxies (δ18O)- compare CO2 and T
Paleocene-Eocene Thermal maximum
56Ma- sudden massive injection of light C into atmosphere-ocean: 3000-10,000PgC, 3000-20,000 yrs, 5-7º warming
δ13C, δ18O drop ~2%
PETM theories
destabilization of methane clathrate
injection of magma into organic C reservoir (FF reservoir)
degradation of permafrost C reservoir in Antarctica (no Ant. ice sheet at this time)
excess PETM C removed from atmosphere-ocean system
over 120-200 years
destabilization of methane clathrates
methane trapped in ice– exists under cold T and high P
found today in deep ocean and beneath permafrost
PETM consequences
ocean acidification- extinction of deep sea life, many corals
mammals got smaller and diversified
evolution of first primates
Quaternary
last 2.6Ma
cyclic glacial/interglcial cycles
early homosapiens lived through glaciation
earliest known fossil of Homo Sapiens
East Africa, 195,000yrs
Glacier mass balance =
snowfall - melt
snowfall - (calving + melt)
ELA
equilibrium line altitude
between net gain and net loss
snowfall = melt
net mass balance > 0
snowfall > melt
net gain of snow, accumulation
if glaciers didn’t flow
they would steepen
flow conveys mass from high–low elevations, and changes equilibrium (lower elevation)
snow –ice
snow: 90% air, aged crystals become rounder and fuse together
granular ice: 50% air, air bubbles start to seal off and snow forms ice
firn: 20-30% air
glacial ice: 20% air- trapping atmosphere at time of ice formation
higher mass glacier
more flowing outward
more calving
Dome Concordia
Antarctic plateaus
annual T: -51ºC
summer T: -30ºC
surface melt is negligible, only melts at edges
Dome Concordia records
CO2, CH4, ice volume, inferred Antarctic T, for 650,000yrs
all records are tightly correlated with each other
Last glacial cycle in Vostok ice core record
140,000yrs- present
roughly overall decline from ~130,000-20,000
fluctuations line up with human migrations, 4 big events
events in last glacial cycle
Out of Africa
Great Leap Forward
Domestication
Gradual extinction of Neanderthals
modern humans in proximity to neanderthals
55,000yr in Israel
Eemian interglacial
~130,000, high T anomaly due to precession, closer to sun, warmer summers, 4-6m higher seas
Dansgaard–Oeschger events
D-O events, 20-50yrs
glacial melt– fresher sea– less density difference– slow down AMOC– cools NH– too cool for evaporation– can’t grow ice sheet– less calving– less freshening– increase AMOC; (-) feedback
Domestication
~10,000yrs ago
domesticating plants and animals, farming and agriculture, able to establish ‘communities’
Great leap forward
~50,000 yrs ago
Behavioural modernity, beginning of modern human like thinking, artwork, bone tools, jewelry, human ingenuity - to increase survival in extreme climate change?
Heinrich events
150-250years
natural phenomenon in which large icebergs broke off glaciers and traverse the North Atlantic; occurred during past glacial periods; particularly well documented for the last glacial period
what happens in Heinrich event
rapid warmin– cold, heavy ice sheet– very high pressure melts (liquifies) bottom of glacier– surges forward into the ocean– extreme freshening
record of Heinrich events
ice rafted debris, further S than expected for normal calving (b/c they were much larger than normal)
Human movement out of Africa
linked with D-O oscillations, and Heinrich events
Neanderthals
tended to live further N– start to migrate S– run into ‘modern’ humans.. fight? compete? — become extinct
glacial/interglacial
glacial periods are longer
warming is much quicker
timescale btw glaciations =
~100,000 years
eccentricity
comparing orbital cycles w/ glaciation
the only one that really lines up with glaciations is eccentricity, the others are too rapid
warmer winter, colder summer, ice growth
slower snow melt– ↑α– ↓T at high altitude
cooler T at high altitude
boreal shift S– ↑α– ↓T @ alt.— soils freezes, ↑permafrost– ↓CO2, CH4 to atmos.
Reduction in CO2, CH4 sources
less GHGs– (-)radiative F– ↓T– ↓H2Og atmos.— ↓GHG— ↓T– ↑snow and ice– sea level drops
Global sea level drop
cont. shelves exposed– ↑vegetation– ↓CO2, CH4– ↓GHG– (-) rad. F– ↓T
global temperature drops
T has ↓– ↓H2Og atmos.–– ↓precip., wetlands, CH4atmos., GHGs––(-) Rad F–– ↓T global, ocean–– ↑CO2 solubility ocean–– ↑CO2 ocean uptake–– ↓CO2atmos., GHG–– (-)Rad F–– ↓T
Reduced precipitation
Aerosols travel farther–– ↑Fe rich dust in ocean–– ↑phytopl.–– ↓CO2 atmos.–– ↓GHG–– (-) Rad F–– ↓T global
feedbacks ~100,000yrs ago
continue until quasi-equilibrium; small change in radiation received in winter vs. summer is amplified by many feedbacks, ∆ice occurs due to changes in seasonal distribution of E, not change in total E
decomposition
oxygenic- CO2
anoxygenic- CH4
global sea level drop
~120m btw depths of ice age and interglacial
feedbacks, 21,000 years ago
Last Glacial Maximum, all of those feedbacks in reverse
Greenland ice core Temperature proxy
temperature variations are chaotic, more variable, closer to source of main changes (AMOC)
AMOC
Atlantic meridional overturning circulation
T-CO2 in the past
Temperature leads CO2 in the records; not relevant now b/c GHG emissions are unnatural
physics
if ↑GHGs, positive radiative F occurs and Earth must warm until a new global radiative equilibrium is reached
CO2- weathering thermostat
long-term (-)feedback in global C-cycle
1,000,000yr timescale
end of proterozoic, Phanerozoic
glacial cycles
variation in NH summer solar radiation
100,000 yr timescale
Quaternary
last 21,000 years
coming out of last glacial maximum (LGM)
Holocene
last 11,000 years
PETM
Paleocene-Eocene thermal maximum
injection of light C into atoms-ocean for 3-20,000 years
CO2 removed over 120-220,000 years
extinctions of deeps sea life, corals
LGM
21,000 years ago CO2 atmos. ~180ppm 3-5ºC cooler than pre-industrial sea level ~120m lower ~3km ice over Canada
Ice retreat, Holocene
icy till ~7kya
still experiencing isostatic rebound- Canadas coast lowering, sea level rising
Canada ice sheet, LGM
Laurentide
Isostatic rebound
ice melts, land rebounds from weight, creates ‘forebulge’ at head of glacier
some Canada rebound rates
Victoria: -1.mm/yr Richmond: -.9 mm/yr Nunavut: +6.8mm/yr Manitoba: +12 St.Johns: -1 Halifax: -1.2
Insolation curve through last 21,000years
Summer insolation was peaked in early holocene, on the down slope now; minimum at LGM
Mega Fauna extinctions
in 4 continents, extinctions followed human colonization; climate change may have aided extinction but mega fauna survived 18 previous glacial cycles
Events in the Holocene
stable climate, stable CO2, less than 1º T anomaly Catalhoyuk- 10,000 bp first writing- 5,000bp Pyramids of Giza- 4,500bp Qin dynasty- 2,000bp medieval warm period-1,000bp little ice age- 500bp
Çatalhöyük
first stable city
Holocene characteristics
-9000 - 2000
no wild climate fluctuations
CO2 atmos 260-280ppm
onset of agriculture, domestication, modern civilization; in last 20,000yrs only period w/ ~no T anomaly
Qin dynasty
built great wall of China
CO2 rates of change
LGM 180ppm, Pre-Indus 280ppm, ∆0.01ppm/yr
Pre-Indus 280, 2000 380, ∆0.7
1990s 350, 2015 400, ∆2
pre-industrial
1850
longest instrument measurements record
1659
measuring last ~1000 yrs
Tree cores: pick tree type restricted by T, not precipitations; tells about growing season (spring/summer)
Medieval warm period
~1000yrs ago
900-1100 AD
warmest period prior to 20th century, cooler than 1961-1990 mean
coincident w/ 1st viking settlement in Greenland- which collapsed ~300 years later
Viking settlement collapse in Greenland
Dorset culture was adapted to cold, used ice for fishing– warming gave Thule culture the ability to take over
when was the little ice age
1650-1850
Most striking climate event of the Holocene
Little ice age
outside range of internal variability of the climate system- must be change in radiative forcing
Causes of the little ice age
sun
thermohaline
volcanic activity
destruction of people
sunspots as a proxy
less sunspots = less solar output = less 14C (less bombardments)
sunspots and LIA
low # 1650-1700
14C record shows minimum during this period
could explain part of cooling
deepest part of cooling occurred after recovery of solar activity
thermohaline, LIA
weakening- cooler N hemisphere
medieval warm- melting- ↑freshwater
slowdown likely made LIA worse in Europe, not much global change
Volcanic activity, LIA
increased (aerosols); high volcanic activity from 1600-1800; large eruptions injected S into stratosphere (last longer); also high output in 12-1300 w/o cooling
destruction of the peoples of the Americas, LIA
Europe–America contact in 16th century–– diseases endemic to Eurasia/Africa spread to America––decimate indigenous populations––collapse of farmin–– uptake of CO2 by reforestation––cooling
CO2, LIA
big drop in 1650, ~10pm stating in late 1500s
~282ppm –272ppm = cooling of 0.15ºC
what caused LIA
no single hypothesis is enough to explain, combinations of hypotheses given and more are probably the best explanation
Mauna Loa
monthly measurements began 1958, Charles Keeling developed methods to measure CO2 at ppm range
Jan 2014: 397.80
Jan 2015: 399.96
δ13CO2 records
since 1980, atmosphere becoming more depleted in 13C; FFs are enriched in 12C
name of Mauna Loa CO2 record
Keeting Curve
T anomalies
1961-1990 have risen ~0.5ºC
Temperature records
begin in 1700s, global in 1850s
traditionally 2 thermometers to measure daily high and low- manually, daily
now w/ automatic weather stations- every 30s, uploaded hourly
SST records
traditionally w/ a bucket of surface water and measuring its T, obsessively by Royal Navy beginning 19th century
now w/ robotic ARGO floats
robotic ARGO floats
drift around ocean taking T measurements of surface and depths to 2000m, report data via satellite every 2 weeks
ARGO float distribution
March 2015- 3846 floats
pretty good, random coverage, a little less ~90º
change in average surface T, 1901-2012
majority is ~0.6-0.8º (over the 21yrs); fairly globally
changes in surface T, 1979-2014
more variation, shows Arctic amplification– northern latitudes ~2-3ºC, mid latitudes (NH) 0.2-1º,
‘Hiatus’
1995-2005? - decrease/stop of warming; still warmest decade in decadal averages
standard deviations from normal
% > 1σ : 31.7 % > 2σ : 4.6 % > 3σ : 0.27% % > 4σ : 0.006% % >5σ : 0.000057%
sea ice extent
1900-2000
decrease 10-12 – ~6 million km^2
measured by ships until 1970s, then satellite
minimum sea extent
2012- 3.6million sq km
sea ice coverage per month
every year since 2010 has been below 2σ of the 1981-2010 average (increases from nov.-mar)
global average upper ocean heat content
1950-2010; has increased almost 20x10^22J; estimated from T-depth profiles taken by research vessels after WWII; now estimated using ARGO floats
global average sea level
1900-2010 increased ~200mm; measured from tide gauges at sea ports, now from satellites
average sea level change 20th century
2mm/yr
average sea level change 2000-2013
3.3mm/yr
pCO2 and pH records of surface ocean, 1990-2010
pCO2 ~330-380ppm
pH ~8.12 - 8.05
acidifying
cumulative ice mass loss
1992 - 2008
glaciers: 5000Gt
greenland: 3000Gt
antarctica: 2000Gt
Cryosphere measurements
ice sheets measured using satellite gravity measurements, satellite altimetry
small glaciers measure using ablation stakes
solar irradiance measurements
measured from space starting in 1978, slight downward trend; peaked at ~1960, slight decrease now– still within 1366±1 W/m^2
population explosion
industrial agriculture and basic sanitation 1500s, skyrocket from 7 w/i the Holocene
changing populations
↓fertility rate, 2012- 2.35children/woman– population set to stabilize
expanding life expectancy, inertia from past high birthrates population will continue to grow to 9bill. by 2050
nation FF use
burn FF = get wealthy
China 2011 per capita C emissions below American emissions in 1900, but has overtaken US as worlds largest C emitter
emissions by fuel type
coal 43%
oil 34%
gas 18%
cement 5%
USA emissions since 1990
30% of total cumulative anthropogenic CO2, w/ only 4.5% of global population
combustion formula
fuel + oxygen = CO2 + H2Og + heat
path to decarbonization
coal C/H = 2.0 Oil C/H = 0.5 Propane C/H = 0.375 Methane = 0.25 Hydrogen = 0 less CO2, less C, more energy
‘proven’ reserves
coal: 119 years
natural gas: 63 years
oil: 46 years
but there is much more to be found
changes in CO2 coal emissions, 2008, 2010
World: increased 200-250 TgC/yr
Developed world: decreased 50-100 TgC/yr
China + India = 127% of worlds growth
FF and LUC emissions, 1960-2010
FF: 2.5 in 1960– 10 in 2010PgC/yr
LUC: ~1-2 PgC/yr
LUC emissions by region
Temperate: large spike in 1960
Tropics: large increase in 1980-2000
both declining now
heat trapped by GH effect
mostly goes into ocean; small changes in ocean-atoms. heat partitioning have big impacts on yearly global average air T
land + atmos + ice < 50x10^21J
ocean 250x10^21J in 2010
ENSO neutral
warm water off of Australia, cold off of Peru
El Nino
warm water central Pacific, warmer off of Peru; globally warmer on average, heat transferred from ocean-atmosphere
La Nina
very cold water off of Peru; La Ninas tend to follow El Nino; cooler than average, heat transfer from atmos.-ocean
Oceanic Niño Index (ONI)
characterized by 5 consecutive 3-month running mean SST anomalies in the Niño 3.4 region that is above the threshold of +0.5°C
Nino 3.4
between 5ºN and 5ºS and 120–170ºW
climate model
numerical representation of the climate system based on physical, chemical, biological properties of its components; their interactions and feedback processes, and accounting for some of its known properties
climate model hierarchy
the climate system can be represented by models of varying complexity; differing by # of spatial dimensions, extent to which processes are explicitly represented, or level at which empirical parameterizations are involved
climate models are composed of
components or modules which simulate a particular part of the Earth system; ex. atmosphere, ocean, land surface, ice sheets, sea ice, clouds
climate model components are represented
mathematically either as dynamics or parameterizations
model dynamics are
processes that can be fully described by laws of physics within computational limits of computer resources
parameterize
system is too complicated– mathematical relationships fitted to empirical data about the system to capture how the system behaves under varying conditions
fluid motion on a sphere
Navier-Stokes equations
cannot be solved using analytical pen and paper mathematics, can be solved using numerical methods (computers); simulate motion of atmosphere and oceans
parameterization example
Duck- complex biological system; parameterization captures the shape of the duck and can waddle like a duck
climate parameterization example
big leaf representing land-plant photosynthesis
climate model grid
horizontal grid- latitude-longitude
vertical grid- height/pressure
physical processes in a model- in each ‘square’ of the grid
like the world is made of lego bricks
how climate model works
climate models break world down into grid cells
grid cells
where all of the dynamic equations, radiative transfer, parameterizations are solved for at every model time-step; grid cells exchange info. with their neighbours
grid cells assigned
land-surface/ocean/sea-ice/ice-sheet; and properties- elevation, lake cover, soil type
more grid cells =
better representation of the climate
every doubling of resolution (more grid cells)
8X the computing power
evolution of climate models, processes
1970: rain, CO2, sun
1980: land surface, clouds, prescribed ice
1990: ‘swamp’ ocean (FAR)
1995: ocean, suphates, volcanic activity (SAR)
2001: carbon cycle, aerosols, overturning circulation, rivers (TAR)
2007: chemistry, interactive vegetation (AR4)
evolution of climate models, resolution
FAR: ~500km SAR: ~250km TAR: ~180km AR4: ~110km AR5: 88km testing: 30km
climate models have evolved
from numerical weather prediction models- originally focused on atmosphere; have become more complex w/ computing power
mid 1990s, climate models
atmospheric and ocean models coupled together to create first atmosphere ocean general circulation models
2000s, models
including interactive biology and carbon cycle to create first Earth system models
last few years, models
begun to incorporate dynamic ice-sheets
future models
clouds still poorly represented in models, create largest uncertainty in model projections; developing super-parameterizations of clouds; embed a cloud resolving model within each grid cell
main climate modelling groups
CCCma, Victoria; NCAR Boulder; NOAA, Princeton; Hadley centre, UK; MPI Germany; IPSL France; MIROC, Japan; MRI, Japan; CSIRO Australia
NCAR, 2012
supercomputer- Ranger
housed at Texas Advanced Computing Centre, part of Teragrid
was 30,000X faster than todays desktops, 579.4trillion operations/s (teraflops)
CCCma today
Environment Canada supercomputer in Dorval, Quebec
performs 211.7 teraflops
UVic ESCM
Earth System Climate Model
simulates C-cycle and ocean heat uptake changes on long timescales (thousands of years)- coarse resolution, simplified atmosphere
how ESCM works
intialize w/ 1800 conditions and keep constant for simulation; run for 10,000 model years to get equilibrated year 1800 climate; simulate from 1800-2000 by giving transient radiative forcing from 1800-present including natural and anthropogenic radiation F
1800 [CO2]
284ppm
10,000 model years
7 weeks on a supercomputer