Global Warming, a liberal plot?

For all my years being involved in following the global warming crisis, the one thing that I haven't been able to figure out is why it became so politicized.  I still don't know the answer to that but I'd like to respond to the constant drum of denial that I see on the internet.  Two of the most frequent arguments raised by the deniers is first: the purported consensus is a creation of government funding for climate research, and second:  it is a liberal plot to ruin our economy.

Well, to both of those I present Exxon.  Their research determined decades ago that gas and oil consumption was going to be a threat to the planet, in fact as late as the 1960's:

A document discovered by DeSmog reveals that Exxon was aware as early as the late 1960s that global emissions of CO2 from combustion was a chief pollution concern affecting global ecology. 

Those details were found in a 1970 report, “Pollution Is Everybody’s Business,” authored by H.R. Holland, a Chemical Engineer responsible for environmental protection in Imperial Oil’s engineering division. [click to download PDF of “Pollution is Everybody's Business]

So is Exxon part of the "liberal plot"?  Or are their results the product of government funding?  No.  Denial of global warming is caused by failing to acquaint oneself with the evidence. There is no liberal plot, and the consensus of climate scientists is real.

The effectiveness of the denial is tragic, for the planet and the people on it.