"The sun is known ( except to Al Gore) as a variable star- NO ARGUEMENT ALLOWED!"

REALLY!???

The sun is a G2V-spectral class main-sequence star, approximately 20% more massive than the average main-sequence star. Other than quite healthy and husky, it is exactly like the vast majority of stars in the universe.

Like all stars, different latitudes rotate at different rates (like Jupiter, which was on it's way to being a star, but fell way short in accumulating enough mass), which, over a few years, mis-aligns its magnetic field. Every eleven years, the magnetic field re-aligns itself, and this is the cause of sun-spots and solar flares. It also goes through longer term cycles, such as a minimum periodic sunspot activity in the 17th century, decreasing luminosity over a few of the 11-year cycles, which lowered the earth's temperature by a few degrees, causing what has been referred to as "the Little Ice Age" in Europe.

There is no indication that such an increase or diminution of luminosity is occurring at the present time, save for the normal, expected 11-year sunspot cycle, which is due to reach its peak in 2012, then wan again.

And no indication of a longer term increase in luminosity occurring at the present time.

In fact:

1. It is currently in the midst of an unusual sunspot minimum, lasting far longer and with a higher percentage of spotless days than normal; since May 2008, predictions of an imminent rise in activity have been regularly made and as regularly debunked by the astronomical community.
2. It is measurably dimming; its output has dropped 0.02% at visible wavelengths and 6% at extreme UV wavelengths in comparison with the levels at the last solar minimum.
3. Over the last two decades, the solar wind's speed had dropped 3%, its temperature 13%, and it's density 20%

Although it has not lasted long enough to indicate a trend, if anything, the sun is cooling, which would tend to point to a repetition of the 17th century's "little ice age." Yet, the mean temperature of the earth has gone UP within the past century, accelerating within the past few decades.

This "The sun is growing warmer" is a favorite dodge of opponents of warnings about human-caused global warming, but it is a) not true, and b) bad science.

Astronomers do not generally regard the sun to be a "variable" star in the sense that opponents of human-caused global warming intend. There are many variable stars in the universe, referred to as "Cepheid variables," and their periodicity is usually short-term, waxing and waning within a few days or weeks, and their spectral characteristics in combination with their clocklike regularity has proven useful to astronomers in determining stellar distances.

If regarded as a "variable" star at all, the sun would fall under the category of an "eruptive" variable, a star that experiences regular eruptions on their surfaces, like flares or mass ejections, as a result of the star's adjusting its periodic rotational misalignments of its magnetic field. This includes our sun, which I have dealt with above. All main sequence stars like our sun do this.

And astronomers do not generally put them into the class of "variables."

Don Firth