This review includes the current state of the art understanding and advances in technical developments about various fields of gas hydrates, which are combined with expert perspectives and analyses.

The present study investigates the evolution of gas hydrate-bearing permafrost sediments against the environmental temperature change.

The geomechanical stability of the permafrost formations containing gas hydrates in the Arctic is extremely vulnerable to global warming and the drilling of wells for oil and gas exploration purposes. In this work the effect of gas hydrate and ice on the geomechanical properties of sediments was compared by triaxial compression tests for typical sediment conditions: unfrozen hydrate‐free sediments at 0.3 °C, hydrate‐free sediments frozen at −10 °C, unfrozen sediments containing about 22 vol% methane hydrate at 0.3 °C, and hydrate‐bearing sediments frozen at −10 °C. The effect of hydrate saturation on the geomechanical properties of simulated permafrost sediments was also investigated at predefined temperatures and confining pressures. Results show that ice and gas hydrates distinctively influence the shearing characteristics and deformation behavior. The presence of around 22 vol% methane hydrate in the unfrozen sediments led to a shear strength as strong as those of the frozen hydrate‐free specimens with 85 vol% of ice in the pores. The frozen hydrate‐free sediments experienced brittle‐like failure, while the hydrate‐bearing sediments showed large dilatation without rapid failure. Hydrate formation in the sediments resulted in a measurable reduction in the internal friction, while freezing did not. In contrast to ice, gas hydrate plays a dominant role in reinforcement of the simulated permafrost sediments. Finally, a new physical model was developed, based on formation of hydrate networks or frame structures to interpret the observed strengthening in the shear strength and the ductile deformation.