Gas hydrates: past and future geohazard?

Area of Science:

• Geoscience
• Climate Science
• Environmental Science

Background:

• Gas hydrates are ice-like structures storing significant methane, primarily in ocean sediments and permafrost.
• These deposits are stable under high pressure and low temperatures, but global warming poses a threat to their stability.
• Current estimates suggest vast quantities of carbon are stored in gas hydrates globally.

Purpose of the Study:

• To assess the potential geohazard posed by gas hydrate destabilization due to global warming.
• To investigate the uncertainties surrounding methane release from marine gas hydrates and its impact on global warming.
• To highlight the increased certainty of permafrost gas hydrate destabilization and associated risks.

Main Methods:

• Review and synthesis of existing estimates of global gas hydrate carbon storage.
• Analysis of climate model predictions regarding temperature increases in high-latitude regions.
• Examination of the potential impacts of ice sheet melting and isostatic rebound on gas hydrate stability.

Main Results:

• Global warming of 3°C could release 35-940 GtC from hydrates, potentially increasing global temperatures by 0.5°C.
• Permafrost gas hydrate destabilization is considered more certain, with high-latitude warming exceeding 12°C.
• Shrinking ice sheets can destabilize hydrates through isostatic rebound and reduced hydrostatic pressure, risking slope failure and tsunamis.

Conclusions:

• Gas hydrate destabilization represents a significant geohazard, with potential to exacerbate global warming.
• Uncertainties remain regarding the rate and extent of methane release from marine hydrates.
• Further research is needed, especially for Arctic and Antarctic gas hydrate reserves, to accurately assess risks.