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Upcoming Seminars



Title:

Fire and ice: Reconstructing paleo-fire emissions using trace gases in polar ice cores

Speaker: Melinda Nicewonger
Dr. Melinda (Mindy) Nicewonger, a National Research Council Postdoctoral Fellow, joined the GMD Halocarbons and other Atmospheric Trace Species Group in October 2019. In the HATS group, Mindy is studying the observations of methyl bromide and methyl chloride to better understand the factors controlling the atmospheric variability in these important ozone depleting gases. Prior to GMD, Mindy earned her PhD from the University of California Irvine. Her doctoral research involved making and interpreting measurements of trace gases from polar ice cores, with an emphasis on understanding variability in biomass burning emissions over the past 2,000 years. Mindy also holds a BS in Meteorology from Texas A&M University.
Date/Time: Thursday, January 23, 2020 11:00 AM
Location: David Skaggs Research Center, GC402 (multi-purpose room)
Abstract
Fire impacts climate through emissions of greenhouse gases, aerosols, reactive trace gases, and by modifying surface albedo. There is debate about how much fire emissions varied in the past and the extent to which humans have altered the fire system. Here we report on the abundance of ethane and acetylene over the last 2,000 years through analysis of air bubbles trapped inside Greenland and Antarctic ice cores. Ethane and acetylene levels in the preindustrial atmosphere are controlled mainly by fire emissions, thus making them a suitable proxy for paleo-fire emissions. Using a global chemistry transport model, we can quantify fire emissions from the paleo-atmospheric abundance of ethane and acetylene. We find large changes in fire emissions occurred over the last two millennia concurrently with known shifts in climate and human population. To better quantify the climate driver of fire, the ethane and acetylene ice core records were extended to 52,000 years ago. A brief summary of the results from these measurements will be discussed.


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