3.22 Proxy Records3.22 Proxy Records

3.221 Ice Cores3.221 Ice Cores3.222 Dendrochronology3.222 Dendrochronology3.223 Sediment records3.223 Sediment records

3.224 Agricultural records3.224 Agricultural records

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Proxy RecordsProxy Records

Information from preserved structuresInformation from preserved structures Paleoclimatology – the study of Paleoclimatology – the study of

ancient climatesancient climates No one record gives full picture.No one record gives full picture. Generally compared with other records Generally compared with other records

– sometimes disagree– sometimes disagree Uniformitarianism – processes Uniformitarianism – processes

observed today operated the same observed today operated the same way in the pastway in the past

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Ice CoresIce Cores

Glaciers are remains of previous ice Glaciers are remains of previous ice ages when ice covered 32% of land up ages when ice covered 32% of land up to 2 km thick. to 2 km thick.

Some formed between Some formed between 60-120 00060-120 000 years ago during last glacialyears ago during last glacial

Some are remains from earlier glacialsSome are remains from earlier glacials

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Ice CoresIce Cores

Youtube Video

Review - IsotopesReview - Isotopes one of two or more atoms with the same atomic number one of two or more atoms with the same atomic number

but with different numbers of neutrons.but with different numbers of neutrons. normal oxygen contains 8 protons, 8 neutrons (normal oxygen contains 8 protons, 8 neutrons (1616O) O) a small fraction (one in a thousand) of oxygen atoms a small fraction (one in a thousand) of oxygen atoms

contain 8 protons, 10 neutrons (contain 8 protons, 10 neutrons (1818O) O) – this is an this is an isotopeisotope of oxygen and is heavier than of oxygen and is heavier than 1616O O

1616O will evaporate more readily than O will evaporate more readily than 1818O since it is lighter.O since it is lighter. Hence, during a warm period, the relative amount of Hence, during a warm period, the relative amount of 1818O O

will increase in the ocean waters since more of the will increase in the ocean waters since more of the 1616O is O is evaporating evaporating

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Oxygen IsotopesOxygen Isotopes In sea water Oxygen In sea water Oxygen

16 (16 (1616O)preferentially O)preferentially evaporates leaving evaporates leaving 1818O in the water.O in the water.

High High 1616O Levels in O Levels in ice indicates colder ice indicates colder climateclimate

High High 1818O levels in O levels in shells indicates shells indicates colder climatecolder climate

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1818O IsotopeO Isotope

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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)

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Other GasesOther Gases Trapped Air Trapped Air

– picture of atmosphere picture of atmosphere as snow compressedas snow compressed

– Relative % of each gasRelative % of each gas

– COCO2 2 in ice suggests in ice suggests

warmer temps as it warmer temps as it dissolves out of dissolves out of oceans.oceans.

– Highly variable 180-Highly variable 180-300 ppmv300 ppmv

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Ice CoresIce Cores Vostok AntarcticaVostok Antarctica

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Other substances in iceOther substances in ice Ions Ions

– Na, Cl, S all indicate various climate conditionsNa, Cl, S all indicate various climate conditions

Solid Particles Solid Particles – ash from volcanoes/fires, ash from volcanoes/fires, – dust & rock from meteorite impacts,dust & rock from meteorite impacts,– pollen reveals health of vegetationpollen reveals health of vegetation

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Materials in Ice CoresMaterials in Ice Cores

http://www.ulapland.fi/home/hkunta/jmoore/johnice.html

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DendrochronologyDendrochronology Rings can be counted to reveal ageRings can be counted to reveal age Relative thickness suggests amount of Relative thickness suggests amount of

growth each year if tree is sensitive growth each year if tree is sensitive (limited by certain factors based on (limited by certain factors based on where it grows).where it grows).

Health in a ring suggests precipitation Health in a ring suggests precipitation levels, sunlight atmospheric gases etclevels, sunlight atmospheric gases etc

Rings can be counted from fallen logs or Rings can be counted from fallen logs or using a boring tool similar to retrieving an using a boring tool similar to retrieving an ice or sediment coreice or sediment core

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DendrochronologyDendrochronology Crossdating – using different trees Crossdating – using different trees longer longer

record record

DendrochronologyDendrochronology Dendrochronology, the study of the annual Dendrochronology, the study of the annual

growth in trees, is the only method of growth in trees, is the only method of paleoenvironmental research that produces paleoenvironmental research that produces proxy data of consistently annual resolution.  proxy data of consistently annual resolution. 

Trees add a cone of wood each year.  Initially Trees add a cone of wood each year.  Initially the cells are thin walled to conduct the the cells are thin walled to conduct the abundant spring soil moisture. As soil water abundant spring soil moisture. As soil water declines through the summer, the cells declines through the summer, the cells become thicker-walled and more dense. become thicker-walled and more dense.

Each annual ring consists of early (light) and Each annual ring consists of early (light) and late (dark) wood. late (dark) wood. 

Source: University of Regina - Source: University of Regina - http://uregina.ca/~sauchyn/geog411/dendrochronology.htmlhttp://uregina.ca/~sauchyn/geog411/dendrochronology.html

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DendrochronologyDendrochronology Canadian trees in temperate zones make one growth ring each Canadian trees in temperate zones make one growth ring each

year, with the newest adjacent to the bark. year, with the newest adjacent to the bark. For the entire period of a tree's life, a year-by-year record or 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 ring pattern is formed that reflects the climatic conditions in which the tree grew. Adequate moisture and a long growing which the tree grew. Adequate moisture and a long growing season result in a wide ring. A drought year may result in a very season result in a wide ring. A drought year may result in a very narrow one. narrow one.

Alternating poor and favorable conditions, such as mid summer Alternating poor and favorable conditions, such as mid summer droughts, can result in several rings forming in a given year. droughts, can result in several rings forming in a given year.

Missing rings are rare in hardwood oak and elm trees—the only Missing rings are rare in hardwood oak and elm trees—the only recorded instance of a missing ring in oak trees occurred in the recorded instance of a missing ring in oak trees occurred in the year 1816, also known as the Year Without a Summeryear 1816, also known as the Year Without a Summer

1515

1616

2009

2008

2007

2006

2005

2004

2003

2002

Christmas Tree – 17 years old – cut down Dec 2009• 2002-2004 had more

average warmth and rain during the summers – growth averaged15%/year

• Above average warm and wet summers produce optimal growing seasons such as 2005-2007 – growth averaged17.3% /year

• 2009 had a cool and wet summer, 2008 had a dry and warm summer – growth averaged 9.5%/year

2002-2004

2005-2007

2008-2009

1992-2001

Tree taken from West Carleton ~ 5 km from Stittsville

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Sediment SamplesSediment 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

1818

Sediment SamplesSediment 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

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Sediment SamplesSediment Samples Oxygen Oxygen

incorporated in incorporated in marine shells marine shells formed under formed under cold conditions cold conditions will have elevated will have elevated levels of levels of 1818OO

organisms thrive organisms thrive in different in different temperaturestemperatures

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Coral ReefsCoral 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

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Agricultural recordsAgricultural records Successful farming is key to survivalSuccessful farming is key to survival Accurate records taken back to middle Accurate records taken back to middle

agesages

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Agricultural recordsAgricultural records Crops growing at different altitudes or Crops growing at different altitudes or

latitudes reveals climate conditionslatitudes reveals climate conditions Grapes and olives were luxury items Grapes and olives were luxury items

through history in Europe, so accurate through history in Europe, so accurate records were kept on where these records were kept on where these could growcould grow

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Agricultural recordsAgricultural records Top curve shows Top curve shows

record of frost record of frost dates, dates,

Bottom curve is Bottom curve is temperature temperature proxy from tree proxy from tree ringring

BACKUP SLIDESBACKUP SLIDESProxy RecordsProxy Records

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Ottawa Climate Data 2000-2009Ottawa Climate Data 2000-2009

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