The megavolcano is the most likely scenario. If you want MASSIVE irony, let it be triggered by an attempt to bleed off the heat (hope to delay the eruption by 10,000s of years) and use it for carbon-free geothermal.
https://wattsupwiththat.com/2017/10/30/ … edictions/
https://wattsupwiththat.com/2017/10/29/ … ntarctica/
https://wattsupwiththat.com/2017/10/27/ … old-kills/
http://notrickszone.com/2017/10/23/400- … 9jAb3.dpbs