According to a 2013 IPCC report there is "high confidence" (about an 8 out of 10 chance) that anthropogenic global warming is causing permafrost, a subsurface layer of frozen soil, to melt in high-latitude regions and in high-elevation regions. [ 49 ] As permafrost melts it releases methane, a greenhouse gas that absorbs 84 times more heat than CO2 for the first 20 years it is in the atmosphere, creating even more global warming in a positive feedback loop. [ 50 ] [ 51 ] By the end of the 21st century, warming temperatures in the Arctic will cause a 30%-70% decline in permafrost. [ 52 ] According to a 2012 report, as human-caused global warming continues, Arctic air temperatures are expected to increase at twice the global rate, increasing the rate of permafrost melt, changing the local hydrology, and impacting critical habitat for native species and migratory birds. [ 53 ] According to the 2014 National Climate Assessment, some climate models suggest that near-surface permafrost will be "lost entirely" from large parts of Alaska by the end of the 21st century. [ 16 ]
At the conclusion of the novel, Montag, Granger and the rest of the intellectuals walk up the river to find survivors of the ultimate atomic destruction of the city. In his walk, Montag remembers passages he read in his Bible from Ecclesiastes 3:1, "To everything there is a season," and Revelations 22:2, "And on either side of the river was there a tree of life...and the leaves of the tree were for the healing of the nations." The apocalypse Montag has witnessed has clear connections to the apocalypse foreseen in the Bible.