That site is interesting but here is something I posted in another thread,
Once the maximum carrying capacity is met it might look like a straight line but the numbers alternate between going up and down. These living systems balance themselves out and can be looked at for the population of one species, the carbon cycle, or the water cycle. Until the industrial revolution, the natural world had spent millions of years accumulating carbon into the ground and soaking into the oceans. It doesn't matter whether volcanoes put out more greenhouse gases than the whole human world has since the industrial revolution began, the amount may look insignificant but that is illusion. The carbon we dig up was removed from the system and unused, whereas all of these examples that people try to bring up to deflect the human impact were already being balanced by the world.
It doesn't matter if we release .2% or lower into the atmosphere. The question is how much we can release before the model gets broken and a new one replaces it. Hey it might be a good thing, maybe changing weather patterns will allow us to grow more crops. The "doom and gloom" message that Al Gore had in his movie about civilization falling was about this condition, could humanity learn to repopulate the world if the weather patterns change before massive starvation kicks in? The problem isn't about the Earth becoming inhabitable, it's about how much our societies and the natural world could cope with global changes.
I hope that clears it up some, there are a lot of misconceptions being thrown about by people who have no idea what is going on.
That site agrees that water vapor is a greenhouse gas and is the worst.
So, now we know that the more active sun warms the planet directly with increased incident radiation and indirectly both by reducing low cloud and likely by elevating the proportion of gaseous water -- the most important greenhouse gas.
All I saw that disputed "global warming" was a theory that the sun does more to warm the world. Maybe it does but my point has always been that shifts in weather would have far reaching consequences. When we can control some of that change and make the transition easier better to be safe than sorry.