Methanogenic explosion of Siberian permafrost-mounds over the last three years questions whether this new phenomenon is the first sign of cascading release under climatic warming. Identical mounds occur in their millions on Mars but are uniformly interpreted as ancient volcanic structures, a geomorphic paradigm whose geological basis continues to escape objective observation. Here I show that thousands of Mars' mounds have recently exploded onto overlying aeolian dunes and are thus active and climatogenic, the time-lag between formation and synchronous explosion naturally explained by a trigger of climatic origin. Time-transgressive, mass explosion of a multi-billion-year-aged source has no parallel in rock-forming processes and points to regional-scale mobilisation of volatiles, this abrupt destabilisation event having immediate implications for hypothesised cascading releases from terrestrial clathrate reservoirs. Whether the Siberian explosions are new, or simply newly discovered, is uncertain but their spatial density is 20,000 times lower than on Mars, inconsistent with ongoing, multi-millennial-scale process. We should therefore consider the possibility that they are just beginning and, irrespective of volatile involved, we now have a scaleable example of how they might end. Were the clathrates of the East Siberian Arctic Shelf to degas on the density and frequency of Mars, then the entire reservoir would be depleted and unstoppable runaway warming initiated.