31. More complex clathrates can occur with hydrogen, water and other molecules such as methane, 32. Between 0.7 and 1.1 GPa the clathrate has a tetragonal structure. 33. Nonpolar molecules such as methane can form clathrate hydrates with water, especially under high pressure. 34. In clathrate structures, gases are enclosed in an icy cage and look like packed snow. 35. Polyoxometalates bear similarities to clathrate structures. 36. The cave also releases methane clathrate . 37. The release of the methane clathrates . 38. Estimates of the size of the total carbon reservoir in Arctic permafrost and clathrates vary widely. 39. Kieffer ( 2000 ) suggests no significant amount of clathrates could exist near the surface of Mars. 40. Arctic methane release from permafrost and methane clathrates is an expected consequence and further cause of global warming.
