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A talk about the climate history of earth, and what may have effected it. Given as part of the exam in Climate Physics course at the University of Aarhus
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Climate history of the Earth
ProgrammeClimate Archives
Icecores
Climate Proxies
Oxygen isotopes
Deuterium
…
Milankovitch
Tectonics and Ocean Current
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives
Holds information of climate changes through earth’s history.
General idea: layering of matter
Types: SedimentsOcean coresLake coresIce coresCoralsTree RingsPollenHistorical
Climate Archives: Dating
Radiometric dating
Counting annual layers
Climate Archives: Dating
Radiometric dating
Counting annual layers
Climate Archives: Dating
Radiometric dating
Counting annual layers
Climate Archives: ResolutionDepends onSediment influx rateDepth and rate of mixing
Ice cores
Lake and Ocean cores
Climate Archives: ResolutionIce cores
Climate Archives: ResolutionLake and Ocean cores
Proxy
In statistics, a proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained. In order for this to be the case, the proxy variable must have a close correlation, not necessarily linear or positive, with the inferred value.
Climate proxies are devices that suggest the climate patterns of the past, even before those patterns were archived by humans. To produce the most precise results, systematic cross-verification between proxy indicators is necessary for accuracy in readings and record-keeping.
Ocean Sediments
Fossil remains of plants and animals.
Plankton. Four major groups:Foraminifera, sand-sized, CaCO3 (ul)Coccoliths , clay-sized, CaCO3 (ll)Diatoms, silt-sized, SiO2 (ur)Radiolaria, sand, sized, SiO2 (lr)
Ocean Sediments
Fossil remains of plants and animals.
Plankton. Four major groups:Foraminifera, sand-sized, CaCO3 (ul)Coccoliths , clay-sized, CaCO3 (ll)Diatoms, silt-sized, SiO2 (ur)Radiolaria, sand, sized, SiO2 (lr)
Ocean Sediments
Fossil remains of plants and animals.
Plankton. Four major groups:Foraminifera, CaCO3 (ul)Coccoliths , CaCO3 (ll)Diatoms, SiO2 (ur)Radiolaria, SiO2 (lr)
Ice Core Drilling
Location of Ice Cores
http://www.nicl-smo.sr.unh.edu/maps/world/world.html
Counting annual layering
Air trapped in glacial ice: sintering
Detection of annual layers
Blog
http://adventures-in-climate-change.com/drillingintothepast/
Maria Banks, Ph.D in geology and planetary science.
Ice core drilling in the Antarctica.
Blog: The WAIS Divide field site
Our field site is located on the West Antarctic Ice Sheet (WAIS). At this site, the ice thickness is 11,365 feet. The snow accumulation is estimated at 17 inches/year. This is considered high accumulation for Antarctica. The average temperature at the site is -24 degrees F. This site is a good area to study ice cores because the relatively high accumulation creates thicker layers. Although the depth of the ice and the layers at this location span only the past 100,000 years, their thickness provides high resolution data in comparison to areas with lower accumulation/thinner layers. Also, this field site is located near an ice divide. A divide is a high point on the ice sheet that marks a division where the ice begins to flow in two different directions. The ice near a divide experiences less movement than ice in other parts of the ice sheet and thus the layers are less distorted and easier to analyze.
Blog: Why do we Study Ice Cores?
The goals of the WAIS Divide Ice Core Project are to develop a highly accurate climate record extending back 100,000 years (climatology), to study the stability of the West Antarctic Ice Sheet (glaciology), and investigate bacteria contained in ice cores (cryobiology).Isotopes in the water can be used as a thermometer to measure the temperature when the snow fell. Also, analyzing the chemicals captured by the snow helps determine the age of each layer and gives insight into the amount of winter sea ice surrounding Antarctica. Trapped air bubbles contain greenhouse gases (carbon dioxide, methane) which tell us concentrations of these gases in the air during the past. The electrical conductivity of the ice reveals how much acid is in the snow. Examining the physical properties of the ice yields information about the ice sheet both past and present. Scientists analyze the ice grain orientation which can tell them about changes in the flow of the ice or any unexpected changes in ice movement. This in turn may reveal information about the topography beneath the ice. Bacteria, carried to Antarctica by winds, provide an understanding of whether the Earth’s climate was wet or dry during different periods in the past.
Blog: How much is an ice core worth?
If you average the overall cost of running the project over the amount of core we expect to drill, it is roughly estimated that an ice core 1 meter (~3 feet) in length is worth approximately $20,000 (and possibly much more). This does not including the costs of supporting the lab work and research that produces the science from this ice core. Lets think about the ice that we have been working with at WAIS Divide this season. We pack 4 meters of ice into each core box. There are 8 boxes loaded onto each skid and 4 skids fit on one air force pallet. Using our estimated value for an ice core and completing the math, each air force pallets contains about $2,560,000 worth of ice. So far a total of 12 air force pallets of ice have been packed and sent out this season (ice drilled last season and ice acquired this season) and several more skids are packed and ready to go!Going into the estimate of the worth of each ice core are the costs of drill operation, personnel, core transportation, the costs of running a remote field camp, plus many, many other related expenses. For example, it costs ~$5,000 per hour to fly a Hercules military cargo plane (the planes we use to transport the ice out of the field and to McMurdo Station). This comes to roughly $30,000 per round trip … and that’s just to get the ice to McMurdo Station, not even off the continent! One must also take into account the costs of running and supporting a remote field camp with food and supplies. I have heard that overall there are roughly 5 support staff for each scientist in the field. The ice we handle everyday is literally worth millions of dollars and required years of hard work from many different people in different roles to acquire. Unfortunately, one can’t just hand over $20,000 dollars and get themselves another duplicate ice core. For example, it took almost 5 seasons or 5 years to acquire an ice core from a depth of 2,000m (3 years to set up camp, the arch, and the drill and core processing equipment, and about 2 years of full time (24 hours a day) production drilling)!
Blog: The Daily life
The staff are limited to one 2-minute shower a week!
Blog: The Daily Life
And before they can take a shower, they have to shovel snow to the heater.
Blog: But they also have fun
Antarctic gear twister
Blog: But they also have fun
And mini-golf
Pictures!
http://www.travelblog.org/Antarctica/blog-35013.htm
Lou, Bella and Jay from the University of Wisconsin-Madison are ice core drilling on the Antarctica (in jan 2006).
Core handlingWAIS: Core is removed from drill by a machine
Core handling
Cooled to about -27C
Never warmer than -20C (this is where certain gasses start to leak)
Core handlers take over
http://blogs.nature.com/news/blog/2010/01/antarctica_2010_ice_core_drill.html
Core handling
Depth: 1586 m. Approximate age: 8200 years.
Ash layer from the eruption of a volcano (Mt. Takahe)
Sources of uncertainties
Timescale: +/- 1-2 years
Diffusion
Spatial
Proxies
How to:
Proxies
No direct measurements Indirect measurements by proxies Sensibilities to different variables Separation of variables
Using more proxies then variables Linear dependence (?) Linear combination
Proxies
Oxygen Isotopes Deuterium Carbon Isotopes
Terrigenous components Foram size Lysocline ...
Oxygen Isotopes
O-16 O-17 O-18
99,759% 0,037% 0,204%
Oxygen Isotopes
Oxygen Isotopes
18O= 18O16O
Sample
18O16O
Reference
−1×1000
Reference=SMOW
Oxygen Isotopes - Mechanisms
Evaporation of (light) water Precipitation of (heavier) water
However Snow is lighter
Sea currents and winds Biological activity
Is temperature dependent...
Oxygen Isotopes - SPECMAP
Oxygen Isotopes - SPECMAP
Oxygen Isotopes-Universality
Oxygen Isotopes - Atmosphere
δ18O is +2,35% in atmosphere compared to SMOW Due to Dole effect – Biology
Planktic more subject to temperature
Deuterium
H D H-3
99.985% 0.015% ≳ 0%
Mass (compared to H2O) HDO: +5,5% H2(18-O) +11%
Reduced mass (H-O bond) H – (18-O): x1.06 D – O: x2
Deuterium – A temperature proxy
Deuterium – A temperature proxy
Carbon Isotopes
C-12 C-13 C-14
98,9% 1,1% ≳ 0%
13C=
13C12C
Sample
13C12C
Reference
−1×1000
Reference=Pedee Belemnite PDB
Carbon Isotopes - Mechanisms
Primary biological proxy More life in warmer areas => Natural gradiant of δ13-C =>
Proxy of Currents
Carbon Isotopes
Other
Measure of atmosphere in Icecores CO2 – H2O – Methane …
Pollen Terrigenous Component Foram size Lysocline ...
Phase-problems
Results
Results
Results
Results
Results
Results
100.000 year cycle 41.000 year cycle 23.000 year cycle Narrow spectral peaks Sudden terminations ”Sawtooth” shape
BREAK!
Croll/Milankovitc Cycles
Insolation is the main reason for long-term climatic changes
Shift of eccentricity Shift of axial tilt Axial precession Apsidial precession
Eccentricity (95 – 125 – 400 ky)
Axial tilt (41 ky)
Axial precession (26 ky)
Apsidal precession (21 ky)
Problems with Milankovitch
100 ky problem 400 ky problem Stage 1 and 11 problems Unsplit peak problem Causality problem ...
Stage 1 and 11 problems
Causality problem
Devils Hole, Nevada Timing determined by U → Th decay
”Solutions”
Statistical fluctuations Resonance …
Orbital inclination
Orbital inclination
Shifts in orbital inclination
Shifts from ecliptica in 70ky
Shifts from invariable plane in 100ky
Interplanetary dust
Scattering of Sunlight Formation of clouds Destruction of Ozone
Catlayst Bromine
Formation of Noctilucent Clouds
Noctilucent Clouds
Orbital inclination
Solves some problems: Stage 1 and 11 100 ky Causality
However We need insolation to account for 41 ky and 23 ky No explanation to sudden terminations Uncertanty to how noctilucent clouds behave
Litterature
Wikipedia Ice Ages and Astronomical Causes, Data, Spectral
Analysis and Mechanisms
Richard A. Muller and Gordon J. MacDonald
Ice ages
No ice on earth
PermianOrdocianvi/SilurianLate-Precambrian Qvarternary
Marshak 2001
Climate though 3.900 million years
Glacial striationsFrom the Permian inSouth Africa
Marshak 2001
Permian glacier in Africa
Methods for mapping tectonic movements
• Paleomagnetic compasses in continental basalt ~ 500 million years.
• Paleomagnetic compasses in basaltic oceanic crust ~175 million years.
L.A. Lawver, I.W.D. Dalziel, L.M. Gahagan, K.M. Martin, and D. Campbell.PLATES 2002 Atlas of Plate Reconstructions (750 Ma to Present Day).2002, University of Texas Institute for Geophysics, August 19, 2002
L.A. Lawver, I.W.D. Dalziel, L.M. Gahagan, K.M. Martin, and D. Campbell.PLATES 2002 Atlas of Plate Reconstructions (750 Ma to Present Day).2002, University of Texas Institute for Geophysics, August 19, 2002
Ruddiman 2001, table 05-01
Ruddiman 2001, fig 05-19, p.118
Spreading rate of oceanic crust
Collision of continents formation of mountain ranges upliftweathering use of CO2 through weathering of silicates
CaSiO3 + CO2 CaCO3 + SiO2
Continent-continent collision
kontinent-kontinent kollision
Uplift Weatering Hypothesis– Tectonic Control of Co2 removal
Ruddiman 2001, fig 05-23 top, p. 122
Ruddiman 2001, fig 05-26, p. 124
Ruddiman 2001, fig 04-07
Ruddiman 2001, table 05-03
Recent Climate
• Ocean Circulation
• Last deglaciation
Warm summer’s day in Tromsø, Norway – 70°N
Warm summer’s day in East Greenland – 70°N
Global Ocean Conveyor (Broecker 1992)
Marshak 2001Circulation ~1600 years
Marshak 2001
Ocean Surface Circulation
Ruddiman, fig 14-02
Melting of N American ice sheet
Ruddiman, fig 14-08
Direction of melt-water outflow
Ruddiman, fig 14-05
Fresh-water pulse
Geographical extend and timing
Ruddiman, fig 14-06
Marine and terrestrial evidence
Litterature
• L.A. Lawver, I.W.D. Dalziel, L.M. Gahagan, K.M. Martin, and D. Campbell.PLATES 2002 Atlas of Plate Reconstructions (750 Ma to Present Day).2002, University of Texas Institute for Geophysics, August 19, 2002
• Marshak, Stephen. (2001) Earth Portrait of a Planet. New York, NY: Norton & Company, Inc
• Ruddiman, W.F. 2007. Earth’s Climate. Past and Future (2nd edition). New York, NY: W.H. Freeman and Company, Inc.
• Ruddiman, W.F. 2001. Earth’s Climate. Past and Future (1st edition). New York, NY: W.H. Freeman and Company, Inc
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