1. 3.22 Proxy Records 3.221 Ice Cores 3.222 Dendrochronology
3.223 Sediment records
3.224 Agricultural records
Table of contents

2. Proxy Records Information from preserved structures
Paleoclimatology – the study of ancient climates
No one record gives full picture.
Generally compared with other records – sometimes disagree
Uniformitarianism – processes observed today operated the same way in the past
Proxy records are those pieces of information extracted from preserved structures around the earth. These are studied by “paleo-climatologists”(paleo – ancient) who attempt to recreate past climates based on information from various sources. No one proxy record can create a definitive picture of the climate. The growth of a tree depends on both precipitation and temperature for example, but if the amount of precipitation can be determined from another record, then the temperature can be more accurately estimated based on the growth of the tree.
Most proxy records rely on the geologic principle of “uniformitarianism” which is the belief that organisms and processes at work today operated in a similar fashion in the past. If we understand how something happens now, then evidence of similar occurrences in the past would suggest similar conditions to what we have now.

3. Ice Cores
Glaciers are remains of previous ice ages when ice covered 32% of land up to 2 km thick.
Some formed between years ago during last glacial
Some are remains from earlier glacials
Glaciers are the remains of the last ice age, when glaciers covered 32% of the land and 30% of the oceans. Glaciers are the result of many years of snowfall, each year's snow piling on top of the previous year’s snow. The heavy snow on top exerts pressure on the snow beneath turning it into firn and eventually into ice. Ice cores are long tubes of ice obtained by drilling down into glacial ice.

4. Ice Cores Youtube Video
DESCRIPTION FROM -
The uppermost portions of an ice core have a layered structure that show yearly variation. Extreme pressure crushes the deeper ice layers together so tightly that individual years cannot be distinguished, though lower resolution climate variations can still be discerned. Typically, in ice samples from Polar Regions, the upper layers of ice have alternating light and dark layers. Light bands correspond to the relatively fresh, clean snows that fall in the summer when warmer conditions bring more moisture (and thus more precipitation) to these high-latitude locales. Dark bands mark the polar winter season, when little new snow falls on these frigid deserts and blowing snow is mixed with dust, discoloring the white snow. In many samples, the alternating light and dark layering is visible to the naked eye; in others, the layers can only be found by looking through polarized filters or via chemical analysis

5. Review - Isotopes
one of two or more atoms with the same atomic number but with different numbers of neutrons.
normal oxygen contains 8 protons, 8 neutrons (16O)
a small fraction (one in a thousand) of oxygen atoms contain 8 protons, 10 neutrons (18O)
this is an isotope of oxygen and is heavier than 16O
16O will evaporate more readily than 18O since it is lighter.
Hence, during a warm period, the relative amount of 18O will increase in the ocean waters since more of the 16O is evaporating

6. Oxygen Isotopes
In sea water Oxygen 16 (16O)preferentially evaporates leaving 18O in the water.
High 16O Levels in ice indicates colder climate
High 18O levels in shells indicates colder climate 16 6 6

7. 18O Isotope
The concentration of 18O in precipitation decreases with temperature. This graph shows the difference in 18O concentration in annual precipitation compared to the average annual temperature at each site. The coldest sites, in locations such as Antarctica and Greenland, have about 5 percent less 18O than ocean water. (Graph adapted from Jouzel et. al., 1994)

8. Other Gases Trapped Air picture of atmosphere as snow compressed
Relative % of each gas
CO2 in ice suggests warmer temps as it dissolves out of oceans.
Highly variable ppmv
Air Bubbles – Air in glacial ice represents the atmospheric composition of a time just after the deposition of the snow, once there was sufficient mass above the snow to compress it into ice. These air bubbles are like tiny snapshots, revealing the relative percentages of the various gases in the atmosphere (O2, CO2, NO2, CFC’s, CH4 etc).
GRAPH - The percentage of carbon dioxide and methane in the atmosphere above Antarctica for the last 150,000 years has been measured in air bubbles enclosed in a long Antarctica ice core.
Variations of GHG’s have closely paralleled the temperature record. For example, during the Holocene interglacial CO2 concentrations have varied between 200 and 300 ppmv (parts per million unit volume). and during the Isotope Stage 5e Eemian/Sangamon interglacial 125,000 years ago CO2 concentrations were around 280 ppmv.
The Russian Antarctic ice-core data indicates that during the last glacial maximum CO2 concentrations were around 180 ppmv. As this data indicates the level of CO2 in the atmosphere is highly variable. 8 8

9. Ice Cores
Vostok Antarctica

10. Other substances in ice
Ions
Na, Cl, S all indicate various climate conditions
Solid Particles
ash from volcanoes/fires,
dust & rock from meteorite impacts,
pollen reveals health of vegetation
Other Ions – Sodium, Chloride and Sulphate ions all indicate various climatic conditions
Air Bubbles – Air in glacial ice represents the atmospheric composition of a time just after the deposition of the snow, once there was sufficient mass above the snow to compress it into ice. These air bubbles are like tiny snapshots, revealing the relative percentages of the various gases in the atmosphere (O2, CO2, NO2, CFC’s, CH4 etc).
Solid Particles – ash, dust & pollen reveal information about volcanic eruptions and vegetation health of the time when the snow was first deposited.

11. Materials in Ice Cores 11 11

12. Dendrochronology Rings can be counted to reveal age
Relative thickness suggests amount of growth each year if tree is sensitive (limited by certain factors based on where it grows).
Health in a ring suggests precipitation levels, sunlight atmospheric gases etc
Rings can be counted from fallen logs or using a boring tool similar to retrieving an ice or sediment core
The relative thickness of tree rings indicates the amount of growth each year and is suggestive of a variety of climatic conditions.
Sensitivity – if there is a limiting factor on the growth of a tree, then ring thickness will indicate when that factor was in abundance. Trees growing part way up a mountain might be sensitive to colder summers, while those away from water sources are limited by rainfall.
Today, trees on California mountains are studied to see how they grow at different altitudes and this information is used to determine what climate conditions were like in recent centuries based on growth rings compared to present day growth patterns.
Investigating the actual cellular health of the various tissues in each ring can provide further information. Some of the information gathered from dendrochronology includes temperature, precipitation and exposure to sunlight, amount of Carbon Dioxide in the atmosphere.
The DCCD Project website includes a map of all areas where tree ring study is occurring in Europe

13. Dendrochronology Crossdating – using different trees  longer record
Where a single tree core leaves off, older preserved cores can pick up the trail to past climates. Comparing similar sections of two records allows for a continuous record longer than the life of a single tree.
See image source for excellent background info on dating trees

14. Dendrochronology
Dendrochronology, the study of the annual growth in trees, is the only method of paleoenvironmental research that produces proxy data of consistently annual resolution. 
Trees add a cone of wood each year.  Initially the cells are thin walled to conduct the abundant spring soil moisture. As soil water declines through the summer, the cells become thicker-walled and more dense.
Each annual ring consists of early (light) and late (dark) wood. 
Source: University of Regina -

15. Dendrochronology
Canadian trees in temperate zones make one growth ring each year, with the newest adjacent to the bark.
For the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring. A drought year may result in a very narrow one.
Alternating poor and favorable conditions, such as mid summer droughts, can result in several rings forming in a given year.
Missing rings are rare in hardwood oak and elm trees—the only recorded instance of a missing ring in oak trees occurred in the year 1816, also known as the Year Without a Summer

16. Christmas Tree – 17 years old – cut down Dec 2009
had more average warmth and rain during the summers – growth averaged15%/year
Above average warm and wet summers produce optimal growing seasons such as – growth averaged17.3% /year
2009 had a cool and wet summer, 2008 had a dry and warm summer – growth averaged 9.5%/year
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2001
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2004
2005-
2007
2008-
2009
2009
2008
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2006
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2004
2003
2002
Tree taken from West Carleton ~ 5 km from Stittsville

17. Sediment Samples
Type of rock that is formed by the deposition of sediment
In aquatic environments change based on the amount of rainfall bringing sediment into the basin
the thickness and types of material in each layer provides information.
Provide evidence of climate from more than one million years
Type of pollen = plants present = temperature
Microscopic organisms in sediment cores from lakes and oceans = isotopes of oxygen present in shells = temperature of water
Sedimentology is another important proxy record. Sediment layers in lake and ocean beds change based on the amount of rainfall bringing sediment into the basin, so the thickness and types of material in each layer provides information.
Even more important are the organisms preserved in each layer. Microscopic organisms hold evidence of the climatic conditions during their lifetime. The oxygen isotopes in their shells reflect the temperature as O-18 is more readily available than O-16 during colder periods. The pattern in their shells reveals temperature conditions as does the types of organisms present, with some thriving in colder waters and some in warmer waters. Studying the percentages of organisms in waters today with known temperatures gives paleo-climatologists an excellent profile for what relative numbers suggest about past environments. 17 17

18. Sediment Samples
Annual sedimentary layers produce alternating light and dark-coloured sediments
Summer
thick deposits of coarse light-coloured sediments = meltwater washes sediments into lakes
Winter
fine, dark-coloured sediments
Sedimentology is another important proxy record. Sediment layers in lake and ocean beds change based on the amount of rainfall bringing sediment into the basin, so the thickness and types of material in each layer provides information.
Even more important are the organisms preserved in each layer. Microscopic organisms hold evidence of the climatic conditions during their lifetime. The oxygen isotopes in their shells reflect the temperature as O-18 is more readily available than O-16 during colder periods. The pattern in their shells reveals temperature conditions as does the types of organisms present, with some thriving in colder waters and some in warmer waters. Studying the percentages of organisms in waters today with known temperatures gives paleo-climatologists an excellent profile for what relative numbers suggest about past environments. 18 18

19. Sediment Samples
Oxygen incorporated in marine shells formed under cold conditions will have elevated levels of 18O
organisms thrive in different temperatures
Sedimentology is another important proxy record. Sediment layers in lake and ocean beds change based on the amount of rainfall bringing sediment into the basin, so the thickness and types of material in each layer provides information.
Even more important are the organisms preserved in each layer. Microscopic organisms hold evidence of the climatic conditions during their lifetime. The oxygen isotopes in their shells reflect the temperature as O-18 is more readily available than O-16 during colder periods. The pattern in their shells reveals temperature conditions as does the types of organisms present, with some thriving in colder waters and some in warmer waters. Studying the percentages of organisms in waters today with known temperatures gives paleo-climatologists an excellent profile for what relative numbers suggest about past environments.

20. Coral Reefs Corals add layers of growth each season
Studied by drilling cylinders
Temperature of surface water is obtained as coral growth depends on water temperature 20 20

21. Agricultural records Successful farming is key to survival
Accurate records taken back to middle ages
Successful agriculture has been critical to man's survival through much of the history of human civilization. Thus even in the Middle Ages scrupulous records were often kept in such centers of learning as monasteries on planting and harvest dates, and first and last frosts. These records are particularly good for grapes, the raw product for wine fermentation, and wheat which was used to make bread.

22. Agricultural records
Crops growing at different altitudes or latitudes reveals climate conditions
Grapes and olives were luxury items through history in Europe, so accurate records were kept on where these could grow
Recall that mountains can have several different climate regions on a single face. By observing how plants “migrate” up and down mountains, humans can gain some awareness of how the climate shifts over time. Pliny the Elder (AD 23-79) described how the Beech Tree (a mountain tree in his time) has once “descended” to the plains of Northern Italy and even into Rome, suggesting that his time was much warmer than earlier times.

23. Agricultural records Top curve shows record of frost dates,
Bottom curve is temperature proxy from tree ring
Successful agriculture has been critical to man's survival through much of the history of human civilization. Thus even in the Middle Ages scrupulous records were often kept in such centers of learning as monasteries on planting and harvest dates, and first and last frosts. These records are particularly good for grapes, the raw product for wine fermentation, and wheat which was used to make bread.
In the diagram curve 1 shows variations in mean 16th Century Franco-Swiss wine harvest dates.
Curve 2 shows available dendrochronological data from oak trees in Odenwald. It is interesting to note that this curve closely matches the agricultural harvest record.

24. Proxy Records
Backup Slides

25. Ottawa Climate Data