Quote from jem:
hey fc... until I learned that there is no discernable warming outside natural variation since the industrial revolution I would have said mans activities are contributing to the warming.
I probably did say it here.
That is a far different statement than saying the very small fraction of of greenhouse gas that is man made co2 is causing warming.
The former is a broad statement which is almost a tautology... the later is a specific statement subject to proof which currents has not proof.
man made CO2 is such a tiny part of greenhouse gases there is very little chance it will have a significant effect on temperatures.
Water vapor is showing to have far greater effect.
And it makes sense. generally as temperatures go up air contains more water vaper and we get clouds. Clouds hold the heat in at night. The earth warms up quick the next day. It begins the famed feedback cycle.