Cryo-methane: Ice, Permafrost, Hydrates and Guns

Methane, the most abundant organic molecule on Earth, is ubiquitously distributed in rocks, sediments, soils, water columns of the geosphere. Because we still use methane as a natural gas fuel to run our energy economies, it remains important to understand its formation, distribution and consumption. However, it is also a strong GHG in the troposphere contributing increasingly to our global radiatively balance. By far, the largest repositories for methane are the marine and terrestrial hydrates (~ 5 - 36 x 10⁵ Tg CH₄). It is postulated that massive, catastrophic releases of methane from hydrates to the troposphere (‘Clathrate Guns’) are responsible for the changes in atmospheric methane, and drive climate change, in concert with CO₂. Using stable isotope signatures, this presentation takes you on a circuitous walk through our research on Hydrate Ridge, Santa Barbara Basin, north Canadian permafrost and Greenland ice to investigate the rapid rise in methane at the Younger Dryas-Preboreal transition around 11 ky BP. The results may surprise you as much as it did us.