The precautionary principle (not to be confused with a principal - the person in charge of the high school you should go back to) doesn't apply to this discussion. I am not claiming that global warming isn't harmful, I am simply asking you to substantiate your claim that all possible causes other than human actions have been exhausted.
You appear to have now admitted that this is impossible, thus rendering your use of a popular quote completely invalid. If that's the case, I'm quite happy with the outcome.
Never throughout this discussion have I claimed we shouldn't be addressing global warming - this is an assumption you made.
First, let me again reiterate the point that
this is not the place for the use of ad hominems. This is not the Youtube comment section, if you'd like to resort to this sort of childish dribble, i'd suggest you argue your points somewhere else. This is the
second time I've had to make this clear, i hope participants on this thread understand that such antics have no place here.
Back to the topic, name one time that quote has been used to refer
every single possibility that is available. Understanding the connotation of this phrase is much more important than the denotation. If you had actually taken the time to read the passage from which this quote is taken, maybe you'd better understand this.
On another note, lets just walk through where the energy in the atmosphere comes from.
We have the most obvious source, which is, as you all may guess, the sun. Then we have heat from inside the earth, being released by the decay of radioactive elements and from tidal friction caused by the moon and sun. The energy from inside the earth keeps the interior molten, however, its effect on global air temperatures is rather negligible compared to the sun, and does not vary greatly. So for the most part, energy from the sun is what causes fluctuations of the planet's atmosphere, and different conditions on the planet can create vastly different atmospheric outcomes.
There are mainly three different Earth-centered reasons for climate change, involving the Earth and it's position and orbit in space. These is eccentricity, obliquity, and precession. Increasing eccentricity (how elliptical the orbit is) will result in more extreme seasons. Obliquity is the tilt of the earth's axis. Our current obliquity is 23.4 degrees. Obliquity determines how extreme (or not extreme) the seasons will be. Precession is the direction of the tilt, and doesn't have much of an effect on climate. All three of these occur over long periods of time, and therefore cannot be credited with recent warming.
I'll stop teaching about causes for climactic change. You can take a textbook for a day and figure it out. The sun's cycles have not made a significant change in energy output, enough to change the climate so drastically.
The only variable that has changed significantly is greenhouse gasses.