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Climate Change - How do we know what it was like long ago?. Tree rings - thicker rings in warm/wet springs - thinner in cool/dry years Rings can be counted from fallen logs Climate records for up to 1000 years. Christmas Tree – 17 years old – cut down Dec 2009.

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Climate change how do we know what it was like long ago

Climate Change

- How do we know what it was like long ago?


Climate change how do we know what it was like long ago

  • Tree rings - thicker rings in warm/wet springs-thinner in cool/dry years

  • Rings can be counted from fallen logs

  • Climate records for up to 1000 years


Climate change how do we know what it was like long ago

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

2008-

2009

1992-

2001

2002-

2004

2005-

2007

2009

2008

2007

2006

2005

2004

2003

2002

Tree taken from West Carleton ~ 5 km from Stittsville



Climate change how do we know what it was like long ago

  • Ice Cores rings analyzed: air bubbles trapped in glacial ice record ancient atmospheric composition (e.g. CO2 , methanecontent)

  • Antarctica/Greenland – some ice cores are ½ million years old! (2 km deep)



Climate change how do we know what it was like long ago


Climate change how do we know what it was like long ago

  • Fossils rings analyzed – organisms are adapted to specific climates….so the types of fossils found tell uswhat the climate was like at a certain time.

  • E.g. seashells found in Arctic suggest that 4 million years ago, it was 10-20 degrees warmer

  • E.g. dinosaur fossils in Canada!


Climate change how do we know what it was like long ago

  • Coral layers rings analyzed– annual growth rings

  • Some deep-sea coral skeletons are 40,000 years old

  • Chemical composition of the layers changes with the climate

  • Also, coral growth will change depending on the temperature of the water

Growth rings in coral


Climate change how do we know what it was like long ago

Often, climate scientists put their data together from all sources to look for similarities and correlation