1 Geologic Perspective on Climate  El Nino  The last 1,000 Years: Natural Variability?  The Ice Ages and their cause  The world the Dinosaurs inhabited  The role of Greenhouse Gases in Climate Change

2 Normal Pacific Circulation

3 El Nino Pacific Circulation

El Nino Sea Surface Temperature Animation

El Nino Sea Surface Temperature Animation

6 Current El Nino Sea Surface Temperature Animation noaa.gov/map/c lim/sst_olr/el_n ino_anim.shtml

7 Fig

8 Effects on North America

9 Sources of past climate information  Historical records  Tree rings  Sediments  Marine and lacustrine  Corals  Ice cores

10 The Last 1,000 Years Crowley, Fig. 1

11 The Last 18,000 Years Crowley, Fig. 2 Last Glacial Maximum

12 Iowa 16,000 Years Ago? Graphic from Illinois State Museum

13 Ice on the Retreat! Graphic from Illinois State MuseumIllinois State Museum

14 The Last 160,000 Years Crowley, Fig. 3 Interglacial Glacial

15 CS Fig

16 The Milankovitch Theory  Changes in the amount of solar insolation reaching the Earth at 65°N latitude during the summer drive the waxing and waning of the ice sheets Low summer insolation = glaciers build up High summer insolation = glaciers melt

17 Greenhouse Gas Concentrations Crowley, Fig 4 See Fig

18 The Last 800,000 Years Crowley, Fig. 5 More often glacial (cold) than interglacial (warm) in last million years !!

19 The Last 100 Million Years Crowley, Fig. 6 ICEHOUSE WORLD GREENHOUSE WORLD GH: ~200 My ~350 My ~500 My IH: ~290 My ~450 My ~680 My ~750 My ~950 My ~2300 My

20 The Geologic History of Ice Ages Source:

21 Lush but Dangerous World Crowley points out that if we burn all of the fossil fuel that is available to us, most of which is in the form of coal, CO 2 levels would likely rise to those associated with the Cretaceous period, ~150 to 65 million years ago. The Cretaceous had: - no ice - vegetation all the way to the poles - cold-blooded animals (dinosaurs) If all the ice were to melt, sea level would rise 70 m (~200 ft)