This thread made my head hurt until I went and read the BBC article.
At first I thought we were discussing a mass increase due to the energy being released by nuclear decay inside the Earth and was getting extremely confused. If mass was being converted to energy of which at least some should be radiated into space, then shouldn't the planet be getting *lighter*?
Then I saw that they were talking about global warming as adding energy which I take is what they mean by mass increase by equivalency. Meaning energy added from the *outside*, i.e. the sun, is trapped by greenhouse gases and is increasing the Earth's mass by m=E/c^2, where E is the additional energy held on to, so to speak, by greenhouse gases as part of AGW.
Did I get that right?