Explain the main reasons why pressure and temperature play a critical role in the stability of gas hydrates. Name two situations where methane hydrate deposits predominantly occur and discuss the key challenge (s) in locating and harvesting methane hydrate under each situation.

Using the phase diagram of methane, the pressure and temperature play a critical role in its stability since a slight change in the pressure or temperature will cause a phase change. At low temperature and high pressure, methane hydrate becomes solid (methane hydrate + ice). When the temperature is increased, it becomes liquid. This is one of the main challenges in harvesting methane hydrate, its instability.