Title: The Clathrate-Climate Conundrum
Abstract: Evidence suggests that methane hydrates occurring at the “feather edge” of their stability zone on upper continental slopes of global marine margins are now undergoing dissociation due to the impingement of warming intermediate ocean waters, a process also invoked in the “Clathrate Gun Hypothesis” for the Late Quaternary. Recent studies show that the uppermost ocean has absorbed much of the excess heat associated with Earth’s greenhouse warming over the past few decades. Thus, methane hydrate outgassing now underway on upper continental slopes is expected to continue and eventually affect even deeper parts of the continental slope gas hydrate province. Despite the progress on identifying loci and mechanisms for upper slope gas hydrate degradation, critical questions--indeed even conflicts--remain about the impact of the released methane on the climate system. Some predict that catastrophic methane release to the ocean-atmosphere system from dissociated marine hydrates will lead to enhanced global warming due to the elevated greenhouse gas potential of atmospheric methane. Finding no evidence that methane from upper continental slope seep sites crosses the sea-to-air interface, others argue that gas hydrate degradation may be relatively benign for the climate system. This presentation will detail our efforts investigating this clathrate-climate conundrum through advances in technology, field and laboratory measurements, and regional/isotopic modeling.