I would agree that the mid-Pliocene appears to be our near term future best as the models can tell us - comparable levels of CO2 and mean temperture. What would be the consequences of that to industrial civilization? It is easy to say "too many variables to accurately predict the future from current events" but that is not the task at hand. There is general agreement that at a high level of approximation industrial civilization is having a consequential impact on climate. Many of the possible developments would have adverse impact on people. Significant reduction of CO2 emissions is a reasonable response to our level of knowledge about the future based on the state of climate science at this time.
I guess it all goes to perception -- not only what people want to believe but also how information and arguments are presented to them. My little compact car's four cylinder engine produces about 125 bhp of mechanical output and 500 hp in waste heat, a pretty average 20% efficiency for a modern gasoline engine. At full throttle, the W-16 engine of the Bugatti Veyron cranks out 1,000 bhp with 2,000 hp of heat, for 33% efficiency. Never mind that the Veyron, wide open, will burn more gasoline in a few minutes than my car would in a month of normal driving, it is by the numbers much "greener." The numbers don't lie.
"Green" has lost its ecologically sound meaning and has become a marketing buzz word. It would be more useful to look at a product's or a technology's qualities such as its efficiency and impact on the environment (and I don't mean "carbon footprint"). Spiritually, for those of us who know we all have a soul, there is much good to be had in caring about how our actions and choices affect the world. From a purely economic point of view, there is always money to be found in doing something in a better way and you might find that, along the way, it includes saving your investment, our planet, your family and yourself.
Global warming involves increasing concentrations of CO2 and other greenhouse gasses in the atmosphere with tropospheric warming and consequent cooling of the stratosphere. Shifting weather patterns with unusual weather is to be expected. If there is sufficient fresh water melted off of the Greenland ice the Artic ocean could potentially change enough to stop the Gulf stream current that could lead to extreme cold in the northern hemisphere. The Keeling curve is a record of rising CO2 concentrations. Global average mean temperatures have risen despite the bitter winter.
I was just at a seminar today with some guy plugging his "green" business (coal and petroleum products--even plastics BAD! Electric cars GOOD!). I wanted to ask the guy how he expected that the electricity to be generated without coal and petroleum products, but I let him go merrily on his way...