Am I the only one who happened to watch a Link TV documentary back in 2009 of European (Scandinavian, I believe) scientists studying temperature change due to Global Warming (Climate Change not in the vocabulary yet). I had missed the beginning, and they were summarizing their projection. First, they saw that the steady straight line temperature increase would cause the permafrost to thaw. This would cause methane to be released which is some 28-80 times worse than CO2 (80 initially then it degrades). The temperature curve started an upward rise.
After about 25 years as I recall this temperature spike warmed the oceans 5.6°F, which caused the vast liquid methane pockets at the bottom of river estuaries to turn to gas. The temperature curve then took on a parabolic rise.By 2082, as I remember, their model predicted an 18® F temperature rise! They pointed out matter-of-factly that in past geological eras these were ages of mass extinctions.