The sun spot cycles combining with the warming trend is hard science. We can go back to the middle 1600's and examine these 'Maunder Minimum' periods, and see the result. There was a 50 year period from roughly 1650 to 1700 where there was little to no sunspot activity...and that brought on what was called the Little Ice Age...The Year Without a Summer....ice on lakes in the Northeastern part of this country in June.
The earth's climate does shift, and science can point to that through the ice shelf records.
The thing is, we have such a little snapshot of 'recorded history', that I think some folks have overreacted based on our minute amount of data sampling.
SHould we control emissions? Yes, because that would be good for the air that people breathed, etc. But I just don't think there is manmade global warming.
The amount of 'bad air' that a volcano can belch out (and that has happened, and it has changed the worldwide climate) is incredibly more dangerous than what man can produce, for a variety of reasons.