NOAA's National Climatic Data Center just released today their global temperature dataset for the year ending 2011 (and yes, they conducted another bizarre revision of the entire historical dataset - more on that in a later posting). (click on images to enlarge)
The chart on the left plots the NCDC global temperatures for the last 15 years ending 2011, plus the atmospheric CO2 levels. As the empirical evidence undeniably shows, there is no correlation between global temps and CO2, and the blue curve actually suggests a movement towards a cooling era.
The linear trend for the NCDC temperatures represents an increase by year 2100 of only +0.40°C degree - definitely not "accelerating" warming using anyone's definition. (see new post on "accelerating" here)
The measly "global warming" of the last 15 years is one story and another interesting story about global warming is found in looking at the last 100 years. When the 100 year span is broken into 50-year segments, one ending 2011 and the other ending 1961, the myth of dangerous global warming from human CO2 emissions really starts to unravel. (see update with HadCRUT temperature data)
The first red bar on second chart (chart on right) represents the increase of the 2011 mean temperature over that of 1961; the second red bar represents the increase of the 1961 mean temperature over that of 1911. Clearly, the increase of the mean temperature during the first 50-year period surpasses that of the last 50-year period ending 2011.
And the greater increase in mean temperature during the first 50 year period took place with a smaller increase in atmospheric CO2 levels, as depicted by the grey bars. In fact, the CO2 level increase over the last 50 years was greater than 4 times the earlier 50-year period.
The take home from both charts is rather simple and obvious: the urban myths of accelerating, unequivocal, irreversible, unprecedented, rapid, dangerous modern warming from human CO2 are just that - myths. In addition, these two charts reveal that any proposal suggesting that by controlling CO2 emissions it would be like controlling a global temperature "thermostat" is a bogosity bordering on insanity.
Summary: Both global warming and cooling have happened in the recent past, and both will occur again over the next 100 years, regardless of CO2 emissions.