Seminar by Michael Whiticar on March 16, 2016

Understanding and Tracking Some Critical Methane Interactions between Geo-, Hydro-, Cryo- and Atmosphere
Michael Whiticar

Wednesday, March 16, 2016
Location: Grad House

Although atmospheric CO 2 (~402 ppm, ~850 PgC) seems to occupy most of the
Greenhouse Gas conversation, it is still important to consider atmospheric methane (1.84
ppm, ~3.7 PgC). From a Global Warming Potential perspective, CH 4 is at least 21x higher
than CO 2 on a 100 yr. basis, and ~56x on a 20 yr. comparison. This leads to a radiative
forcing (RF, 1750 – 2011) of ~0.48 Wm -2 for CH 4 compared with 1.82 Wm -2 for CO 2 , i.e.,
RF CH4 is ~ 26 % of RF CO2 despite a 230x lower burden.

Both natural and anthropogenic sources and sinks contribute to the tropospheric CH 4
fluxes and budget, but the majority of CH 4 is some reduction pathway of organic matter,
frequently by Archaea (methanogens), or by thermogenic maturation. Abiotic methane
does exist, but plays a minor role here, in contrast to Mars.

This presentation takes you on a wild, spatial and temporal tour of the major methane
systems, including wetlands, permafrost, natural gas deposits, cows, and gas hydrates,
etc. We will explore some of the critical and/or controversial components…think ‘termites’
or ‘clathrate gun hypothesis’, etc.

I promise to introduce isotope lines of evidence, but only one equation, as we explore this
oft-ignored, silent but deadly (and odourless) gas.