John nailed it.
"Global warming", or more precisely "Climate Change" has been occurring for millennia, cycling through a variety of "warm cycles" and "ice ages" even for
millions of years, and those cycles will continue to the end of time.
These cycles have been enhanced
to a very minor degree by occasional
cataclysmic volcanic eruptions, which even for their monumental short-term contribution to periods of "global cooling", have been but minor "ripples" in the overall scheme of things.
But is any significant part of it due to "anthropogenic" climate change (due to some human activity)?
IMHO any human contribution to the entire equation is miniscule at best.
As is the chance of affecting the grand scheme of things by some of the extreme and costly efforts, such as restricting the use of "fossil fuels" and "carbon sequestration" which are being promoted by the most vocal wingnuts, have as much chance of ameliorating the situation as a "fart in an F5 (
Saffir–Simpson hurricane wind scale) / EF5 (
Enhanced Fujita Scale) hurricane", or moving beach sand with a million man army equipped with teaspoons.
To butcher a line from Bill Clinton:
"It's the Sun, stupid!" — A complex set of inter-operative solar cycles, the effects of which are clearly revealed by geology and related disciplines such as
Paleoclimatology and
Dendroclimatology as well as other scientific means.
See also this "
List of periods and events in climate history", for some pretty good graphic depictions of climate history including many well before the first humanoids crawled out of the caves and discovered fire.
Human influence? Yeah, like a snowball's chance in Phoenix!