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OLLI WEST: EARTH CLIMATE – WEEK 3
Paul E. Belanger, Ph.D.
FIELD TRIP: NATIONAL ICE CORE LAB
Tuesday September 30, 2014
SPECIAL THANKS TO OUR HOST(s):
•Richard Nunn and other personnel in the Ice Core Lab
FIELD TRIP: NATIONAL ICE CORE LAB
Tuesday September 30, 2014
OLLI WEST: EARTH CLIMATE – WEEK 3
DATA
Western Interior Paleontological Society
EMPIRICAL DATAACTUAL MEASUREMENTS:
ATMOSPHERIC COMPOSITION,
STABLE ISOTOPES, % CO3,
ASSEMBLAGE INFORMATION,
ETC.
EMPIRICAL DATA
•SOME OF THIS DATA YOU CAN’T DO MUCH WITH
•ONE NEEDS TO INTERPRET WHAT IT MEANS
THAT THEN MAKES IT “PROXY” DATA
“PROXY” DATADATA BY WHICH WE MAKE INTERPRETATIONS
EARLY PROXY DATA:
TREE RINGS
Interpretation: dry or wet periods of time
PROXY DATA: LEAVES
Interpretation: Climatic regime: tropical, boreal, etc.
Deep Sea Coring
Ruddiman, 2008
PROXY DATA:
CORE DATA
PROXY DATA:
BENTHIC
FORAMS
PROXY DATA:
PLANKTONIC
FORAMS
STABLE ISOTOPES OF OXYGEN
OXYGEN: 8 protons/8 neutrons At. Mass = 16
• Isotopes: variants in nature that have more or less neutrons than the norm (dominant)
• In the natural world the Standard Mean Ocean Water (SMOW) today contains 2 atoms of Oxygen that have 8 protons and 10 neutrons = mass 18 for every 1000 atoms of “normal” oxygen – mass 16.
• This is measured as the del (delta = difference) of that isotope to the norm: i.e. δO18 = 2 o/oo and measurements are in reference to SMOW
STABLE ISOTOPES OF OXYGEN
IN SEA WATER H2O
OXYGEN in sea water: in reference to SMOW
= positive in glacials (more ice)
= negative farther back in time (less ice)
PROBLEM: no fossil sea water; therefore we rely on measurements from CaCO3 from foram shells, etc. that are in equilibrium with sea water (i.e. proxy data)
ISOTOPIC FRACTIONATIONISOTOPIC FRACTIONATION
WHAT CAN INFLUENCE OXYGEN ISOTOPIC RATIOS IN CaCO3
11o: Ice Volume (salinity) – up to 2 : Ice Volume (salinity) – up to 2 oo//oo oo SMOW:SMOW:
- a result of preferentially evaporating H- a result of preferentially evaporating H221616O O
from the ocean and accumulating it as ice from the ocean and accumulating it as ice on land (up to 100m worth of the ocean on land (up to 100m worth of the ocean
water) – thus enriching the oceans in Hwater) – thus enriching the oceans in H221818OO
11o: Temperature = ~+0.25 : Temperature = ~+0.25 oo//oo oo per drop of a per drop of a ooCC
OXYGEN ISOTOPIC RATIO INFLUENCES IN CaCO3
Local Salinity: ocean / fresh water / Local Salinity: ocean / fresh water /
proximity to rivers, etc.proximity to rivers, etc.
Species habitat: where in the water Species habitat: where in the water column do they live (temp/salinity)column do they live (temp/salinity)
22o INFLUENCES: INFLUENCES:
Species fractionation: a poorly Species fractionation: a poorly understood processunderstood process
ICE CORE DATA
EMPIRICAL DATA: Gas bubbles = % CO2, % O2, %N2, etc.
• Compare: actual measurements you can compare to values today
PROXY DATA: δO18, δC13 , δH2 ,(deuterium), etc. from H2O and correlate it to CaCO3 from Ocean samples
• Interpret: e.g. δO18: ice volume, temperature, salinity
EMPIRICAL AND PROXY DATA
ICE CORES
Brook, 2008 Nature
Empirical
Interpreted
Wikipedia
Proxy data: stable isotopes
- SO – WHAT CONTROLS
CLIMATE
Gerhard et al., 2001
Rohling, et al., (PALAESENS Project mbrs), 2012
1o Forcings
Solar
Luminosity
Atm. Comp.
2o Forcings
Continents
(latitudes & elevations)
Ocean
circulation
weathering
CO2
3o Forcings
Obliquity
Precession
Eccentricity
CO2 /CH4
FEEDBACKS
4o Forcings
Volcanic eruptions
Sunspots
Cycles
El Nino/
La Nina
Cloud
Solar storms
Milankovitchcycles
(forcing factors)
But it’s also CO2 and here’s the geologic proof:
CASE STUDIES:
1.The Paleocene-Eocene Thermal Maximum (PETM) whereby CO2 increased dramatically and climate warmed dramatically as well
2.The Azolla event whereby CO2 dimished dramatically – yet temperature didn’t at much – it’s still being studied
The PETM
PETM - THE LAND RECORD
Bighorn Basin
PETM interval in fluvial deposits with excellent alluvial paleosols - seen as color bands, which are soil horizons
Found in Willwood Fm
Reds, purples due to iron oxides in B horizons
Paleosol DensityPaleosol Density
Pre-PETM
PETM
Bighorn Basin Climate
Plant fossils and isotopes show Mean Annual Temperature of 20o
to 25o C or 68 to 77o F
Similar to Gulf Coast region today
The Azolla event
the massive decrease in
atmospheric CO2?
Bujak, pers. Comm.
UNPRECEDENTED DROP IN CO2
• Eocene: 800,000 years of sequestration of Azolla organic matter
• Slower rates of plate tectonics = lower recycling of carbonate = reduction of CO2 in atmosphere
So what caused the drop in
CO2 in the Eocene and since?
P/E World
No Polar Ice Caps
From Blakey (2007)
ARCTIC EVENTS PROXY DATA
Brinkhuis et al,, 2006
Moran et al., 2006
ACEX Azolla core
• >8 metre ACEX core with 90% Azolla
• Azolla occurs as laminated layers
• indicates Azolla deposited in situ
• bottom-water anoxia at ACEX site
Bujak, pers. Comm.
the massive decrease in
atmospheric CO2?
Bujak, pers. Comm.
UNPRECEDENTED DROP IN CO2
The longer record
THE PRESENT
So what’s going on today?
What’s going to happen in the short-term?
Today’s Unique Event: Anthropogenic Global Warming
Today
CO2 for thepast 400 ky
Pliocene levelsof 400ppm
1946 – 1950
svs.gsfc.nasa.gov
2002 - 2006Temperature
svs.gsfc.nasa.gov
Arctic Sea Ice Extent
If sea-ice continues to contract rapidly over the next several years, Arctic land warming and permafrost thaw are likely to accelerate.David Lawrence, NCAR
Satellite imagery of sea ice extent in September1979, and at a record low in September 2007. Source: NASA
WikipediaSolar irradiance: 342 W/m2
Expected levels of CO2 around 2100 for business as usual
I refer you to Jeff Masters PowerPoint or PDF entitled: Earth's Climate: Where are we at, and where are we headed (click here: PowerPoint-11Mb or PDF-4Mb)
6 slides follow
Correcting for El NiCorrecting for El Niñño and La Nio and La Niñña Influences a Influences
Shows the Global Warming Trend More Clearly Shows the Global Warming Trend More Clearly
How to Abuse Statistics: Choose a Short Time How to Abuse Statistics: Choose a Short Time
Interval and Ignore the Long-Term Trend Interval and Ignore the Long-Term Trend