There have been important criticisms of IPCC recent reports for failing to communicate the dire nature of the current predicament facing civilization – so-called “scientific reticence” – as well as for assuming functional, planetary-effective scale biomass carbon capture and storage in its survivable scenarios [1-3]. In the light of major reports released in 2018 [4,5] which underscore the discrepancy between the current climate trajectory and best-case requirements to maintain global civilization, the current predicament is often described as an “existential” crisis . Part of the confusion appears to stem from the lack of discussion of specific scenarios, such as rapid arctic methane release [7,8], which are not discussed by the IPCC in proportion to their catastrophic potential. This scenario is briefly examined using the Goddard Institute for Space Studies (GISS) ModelE v2 7.50.05 . It is suggested that the results presented here represent a lower bound to climate disruption since in this set-up, neither the oceans nor arctic sea ice (a significant and ongoing runaway feedback ) respond to the changes modeled; namely, a sudden release of stored methane gas.