In the real climate system, the given graph was true in the relatively short period of the 1980s - 90s, the producers have failed to follow their own admonition to avoid the «common mistake when interpreting statistics — look [ing] at them from too short a distance.» (dotearth.blogs.nytimes.com)
In the same way, a «greenhouse gas only» scenario can not be verified by observed data, because the real climate system has evolved under both greenhouse gas and aerosol forcing. (realclimate.org)
There are positive feedback loops in the real climate system that are not modeled in the current version of C - ROADS. (climateinteractive.org)