Temporal constraints on hydrate-controlled methane seepage off Svalbard.

Area of Science:

• Geosciences
• Oceanography
• Climate Science

Background:

• Methane hydrate, an ice-like substance, is stable in deep ocean sediments under high pressure and low temperatures.
• Gas flares observed off Svalbard have raised concerns about methane release due to warming bottom waters and potential acceleration of global warming.

Purpose of the Study:

• To investigate the role of methane hydrates in observed gas seepage off Svalbard.
• To determine the historical duration and driving mechanisms of gas seepage in the region.

Main Methods:

• Analysis of gas seepage at the landward termination of the gas hydrate stability zone.
• Correlation of seepage patterns with historical and seasonal bottom-water temperature fluctuations.

Main Results:

• Methane hydrates play a role in the observed gas seepage.
• Gas seepage off Svalbard has been occurring for at least 3000 years.
• Seasonal bottom-water temperature fluctuations (1-2°C) cause periodic gas hydrate formation and dissociation, concentrating seepage.

Conclusions:

• The observed gas seepage is a long-term phenomenon, not solely a recent response to warming.
• Seasonal temperature variability is a key factor controlling the timing and location of methane release from hydrates.
• Understanding these natural cycles is crucial for assessing the impact of climate change on methane emissions from continental margins.