STOMATAL DENSITY AND INDEX ANALYSIS OF FOSSILIZED PLIOCENE FLORAL REMAINS FROM ELLESMERE ISLAND, CANADA FOR THE IDENTIFICATION OF ANCIENT CARBON DIOXIDE LEVELS

• Main Author: Koewler, Wesley
• Other Authors: Barker, Joel
• Format: Thesis
• Language: English
• Published: The Ohio State University 2016
• Subjects: Atmospheric carbon-dioxide; stomatal density; stomatal index; fluorescent light microscopy; Arctic; Canada; Ellesmere Island
• Online Access: http://hdl.handle.net/1811/76751

The Earth’s climate is changing due in large part to increasing concentrations of greenhouse gases in the atmosphere. Climate modeling suggests that atmospheric CO2 concentration may reach 1000 ppm, and the global average temperature may increase on the order of 2–3 °C over the next century. Despite a high degree of confidence in these predictions on a global scale, regional scale climate effects are less certain, particularly for polar regions. To help reconcile this uncertainty, Pliocene-aged deposits are being examined to help identify the consequence of relatively high atmospheric CO2 concentrations in the Arctic because the concentration of CO2 in the atmosphere during the Pliocene is within the range of those concentrations predicted for the next 75 years. One proxy for past atmospheric CO2 is the density of stoma in the fossilized leaves of Pliocene-aged plants. This study uses mummified needles from a Pliocene-aged deposit in the Arctic to estimate atmospheric CO2. Results indicate a 45.07% decrease in stomatal density from current needles, corresponding to an atmospheric CO2 concentration of ~338 ppmV. This concentration is lower than the present day, and lower than CO2 concentrations for much of the Pliocene, suggesting a late Pliocene age for the deposit. NSF OPP 1026177 grant No embargo