1. Triggers for the Late Ordovician Ice Age: Volcanic Aerosols vs. CO 2 Konrad Cunningham UG Eric Santiago HSS Linda Sohl PI Mark Chandler PI

2. Ordovician Period  Started about 500 million years ago.  Hardly any plants or animals lived on the land; most were in the sea.  Compared to today’s Sun, the Sun of the Ordovician was 4% dim.  Most land masses were in the Southern Hemisphere.

3. The Ice Age of the Ordovician  Lasted ~0.5 to ~1.5 million years.  Some researchers think that there was a high level of atmospheric CO 2  Our hypothesis: the sharp decrease in temperature could have been caused by a combination of low CO 2 and high SO 2 related to volcanic activity in the atmosphere.

4. Paleogeography

5. Volcano locations in the late Ordovician  The volcanoes were part of an island arc between Laurentia and Baltica.  These volcanoes were active and created 5,000 times the volume of ash than Mt. St. Helens’ eruption in 1980.  The eruptions were 3 of the 20 largest events in the last 600 million years.

6. Anomaly Plots for SurfAirTemp CO2=1000 ppm, Solar=96% CO2=500 ppm, Solar=96% CO2=3000 ppm, Solar=96% CO2=1000ppm; Solar=94%

7. Conclusion  Ord_testrun3 shows that a ice age is highly improbable with high atmospheric CO 2, no matter what the level of solar luminosity.  Ord_testrun8 gives us the most probable conditions on Earth that would help create an ice age.  Future simulations will explore the effects of both high SO 2 and low CO 2 on Ordovician climate.

8. References  Alaska Volcano Observatory http://www.avo.alaska.edu/activity/avoreport.php?view=kaminfo&id=199&type=kaminfo&month=October&year=2006  ATMOSPHERIC TRANSMISSION OF DIRECT SOLAR RADIATION AT MAUNA LOA, HAWAII  http://climate.envsci.rutgers.edu/pdf/emissions_0207.pdf http://climate.envsci.rutgers.edu/pdf/emissions_0207.pdf  Global Volcanism Program http://www.volcano.si.edu/  Volcanic SO2 Archive Service http://www.oma.be/BIRA-IASB/Molecules/SO2archive/vs/orbit.php  Mount Pinatubo Eruption http://geography.about.com/library/weekly/aa030901a.htm  Ordovician http://en.wikipedie.org.wiki.Ordovian  Impacts of Volcanic Gases http://pubs.usgs.gov/of/1997/of97-262/of/97-262.html  Ancient Oceans Separate the Continents http:/www.scotese.com/newpage1.html  The Geology of Ohio—The Ordovician http://www.dnr.state.oh.us/geosurvey/oh_geol/97_Fall/ordovici.htm  The size and frequency of the largest explosive eruptions on Earth  Nature and Origin of Life on Planetary Bodies http://www.fas.org/irp/imint/docs/rst/Sect20/A12.html