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3.22 Proxy Records 3.221 Ice Cores 3.222 Dendrochronology 3.223 Sediment records 3.224 Agricultural records.

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Presentation on theme: "3.22 Proxy Records 3.221 Ice Cores 3.222 Dendrochronology 3.223 Sediment records 3.224 Agricultural records."— Presentation transcript:

1 3.22 Proxy Records 3.221 Ice Cores 3.222 Dendrochronology 3.223 Sediment records 3.224 Agricultural records

2 2 Proxy Records Information from preserved structures Information from preserved structures Paleoclimatology – the study of ancient climates Paleoclimatology – the study of ancient climates No one record gives full picture. No one record gives full picture. Generally compared with other records – sometimes disagree Generally compared with other records – sometimes disagree Uniformitarianism – processes observed today operated the same way in the past Uniformitarianism – processes observed today operated the same way in the past

3 3 Ice Cores Glaciers are remains of previous ice ages when ice covered 32% of land up to 2 km thick. Glaciers are remains of previous ice ages when ice covered 32% of land up to 2 km thick. Some formed between 60-120 000 years ago during last glacial Some formed between 60-120 000 years ago during last glacial Some are remains from earlier glacials Some are remains from earlier glacials

4 4 Ice Cores Youtube Video

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

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

7 18 O Isotope 7 The concentration of 18 O in precipitation decreases with temperature. This graph shows the difference in 18 O 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 18 O than ocean water. (Graph adapted from Jouzel et. al., 1994)

8 8 Other Gases Trapped Air Trapped Air –picture of atmosphere as snow compressed –Relative % of each gas –CO 2 in ice suggests warmer temps as it dissolves out of oceans. –Highly variable 180- 300 ppmv

9 9 Ice Cores Vostok Antarctica Vostok Antarctica

10 10 Other substances in ice Ions Ions –Na, Cl, S all indicate various climate conditions Solid Particles Solid Particles –ash from volcanoes/fires, –dust & rock from meteorite impacts, –pollen reveals health of vegetation

11 11 Materials in Ice Cores http://www.ulapland.fi/home/hkunta/jmoore/johnice.html

12 12 Dendrochronology Rings can be counted to reveal age 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). 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 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 Rings can be counted from fallen logs or using a boring tool similar to retrieving an ice or sediment core

13 13 Dendrochronology Crossdating – using different trees longer record Crossdating – using different trees longer record

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. 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. 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. Each annual ring consists of early (light) and late (dark) wood. Source: University of Regina - http://uregina.ca/~sauchyn/geog411/dendrochronology.html Source: University of Regina - http://uregina.ca/~sauchyn/geog411/dendrochronology.html 14

15 Dendrochronology Canadian trees in temperate zones make one growth ring each year, with the newest adjacent to the bark. 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. 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. 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 treesthe only recorded instance of a missing ring in oak trees occurred in the year 1816, also known as the Year Without a Summer Missing rings are rare in hardwood oak and elm treesthe only recorded instance of a missing ring in oak trees occurred in the year 1816, also known as the Year Without a Summer 15

16 16 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

17 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

18 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

19 19 Sediment Samples Oxygen incorporated in marine shells formed under cold conditions will have elevated levels of 18 O Oxygen incorporated in marine shells formed under cold conditions will have elevated levels of 18 O organisms thrive in different temperatures organisms thrive in different temperatures

20 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

21 21 Agricultural records Successful farming is key to survival Successful farming is key to survival Accurate records taken back to middle ages Accurate records taken back to middle ages

22 22 Agricultural records Crops growing at different altitudes or latitudes reveals climate conditions 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 Grapes and olives were luxury items through history in Europe, so accurate records were kept on where these could grow

23 23 Agricultural records Top curve shows record of frost dates, Top curve shows record of frost dates, Bottom curve is temperature proxy from tree ring Bottom curve is temperature proxy from tree ring

24 BACKUP SLIDES Proxy Records 24

25 Ottawa Climate Data 2000-2009 25


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