"According to my definition, there is certainly a greenhouse effect on mars. I think that if you could wave a magic wand and change all the CO2 in mars' atmosphere into N2, that mars would cool a little. Though I would be very surprised if it would be by a significant amount."

Well, it seems to me that the greenhouse affect of the CO2 on Mars should be significantly more than greenhouse affect of the CO2 on Earth. And I'm not saying anyone disagrees with this. Because the reference I quoted says there is about 5 C increase in global Mars' temperature. And what seen said about Earth's CO2 is that it causes the increase in global temperature it around 2 C- and it's the water vapor that adds around 30 C.

As for replacing Mars CO2 with N2, I agree that one should see a decrease of the greenhouse affect, and if that N2 was having an greenhouse affect it be somewhere around .00001 C or in other words essentially none.

But my point was that the article is simply wrong in this regard. And it seems to me quite surprising the article would wrong about this.