It's not honest, the irreversible chain reactions part in particular. The reason Earth isn't like Venus is not the fact that we don't have 100% CO2 atmosphere, it's the fact that we only receive 1.5Kw/meter solar input at the equater verses 2.6Kw/meter solar input AND the fact that being closer to the Sun means Venus lost much of it's hydrogen to the Solar wind early on. Little hydrogen means little water, little water means no plate tectonics, no plate tectonics means no CO2 burial, has ZERO to do with a "run-a-way" green house effect. The Earth has had over 6000 ppm CO2 in the past and during that time, the Cambrian explosion occurred, life flourished like it never has before or since. At present in any given year, 30x as many people die in a given year from cold verses heat. The CO2 is greening the planet. This is a negative feedback not positive feedback event.