“We are pumping carbon dioxide into the atmosphere so fast that it could soar to its highest level for at least 50 million years by the middle of this century.

And that’s even worse news than it sounds, because the sun is hotter now than it was then…”

https://www.newscientist.com/article/2126776-co2-set-to-hit-levels-not-seen-in-50-million-years-by-2050/

~~~

http://droyer.web.wesleyan.edu/publications.htm

Future CO2 and climate warming potentially unprecedented in 420 million years
https://phys.org/news/2017-04-future-co2-climate-potentially-unprecedented.html