2. Location: Between 30°N and 30°S…tropics only Away from major rivers and estuaries

3. Corals are symbiotic with zooanthellae

4. Corals build skeletons from: Calcium Ions Carbonate Ions Trace metals Together: can be used to determine the water temperature when the skeleton was formed Paleoclimatological proxy: like tree rings, fossil pollen, and ice cores

5. Biggest clue Ratio of the rare 18 O isotope/normal 16 O isotope Isotope: a form of the same element that contains equal numbers of protons but different numbers of neutrons

6. How measured? Absolute abundance is very difficult to measure, so scientists compare the ratios to determine ɗ (x) (parts per thousand) See me if you want specifics

7. The rule: The ratio is inversely related to water temperature High ratios of 18 O mean lower water temperatures A temperature change of 4°C corresponds to a ɗ 18 O of about 1 part per thousand

8. Climate Change? Use paleoclimatological proxies, we can determine rate of climate change What makes temperatures cold? What makes temperatures warm? Is change today happening quicker than in the past?

9. Graphing Plot the ratios as a function of age… ɗ 18 O on the Y Analysis Questions…use lots of data 1. Which corals grew during relatively cold temperatures? How do you know? What type of event would make temperatures cold? 2. Which corals grew during relatively warm temperatures? How do you know? What type of event would make temperatures warm? 3. Coral 5 is different with very different ratios in its skeleton. Did it experience rapid cooling or warming? How quickly did this happen? Explain your thinking. 4. Why is rapid change more difficult for biological communities?