The phrase "greenhouse warming" refers to the process where heat from the sun gets trapped in Earth's atmosphere, similar to how a greenhouse traps heat, causing the planet to get warmer. Full definition
This would imply that feedback actually works to reduce the net effect of greenhouse warming, from a sensitivity of 1.2 to one something like 0.6 C per doubling. (climate-skeptic.com)
Their new analysis is based on a computer simulation of the changes in temperature of the atmosphere associated with greenhouse warming. (newscientist.com)
This, unfortunately, is just another example of changing the data to fit the models based on greenhouse warming. (dotearth.blogs.nytimes.com)