NCAR researcher Jeffrey Kiehl discusses his piece in the current issue of Science.
Building on recent research, the study examines the relationship between global temperatures and high levels of carbon dioxide in the atmosphere tens of millions of years ago. It warns that, if carbon dioxide emissions continue at their current rate through the end of this century, atmospheric concentrations of the greenhouse gas will reach levels that last existed about 30 million to 100 million years ago, when global temperatures averaged about 29 degrees Fahrenheit (16 degrees Celsius) above pre-industrial levels.
Much more at Climate Progress.