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

1. Climate Change - How do we know what it was like long ago?

3. 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

4. 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

5. Instead of chopping a tree down, cores can be taken and the rings analyzed

7. Ice Cores: 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)

8. These bubbles are the air of ½ million years ago!

11. Inside the air bubbles can also be found • - dust from volcanoes • - ash from forest fires • - pollen from different plants • All of these tell us what the climate was like!

13. Fossils – 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!

14. Coral layers – 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

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