Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
This graph is the famous hockey stick from previous IPCC Assessments. The graph is controversial because some claim the graph has defects in math, data, mythology used, and or calculations. Apparently, the most significant issues include "Climate Gate" (climatologists' emails hacked and released), the Little Ice Age (which brought us Stradivarius violins), and the medieval warm period (allowed Vikings to settle in Greenland for a short period of time). If adjusted for those periods, based on skeptics, the graph changes significantly. It's rumored, based on leaks, this graph may not be included in the upcoming IPCC Fifth Assessment Report.
But let's give the benefit of the doubt and say it's totally accurate; we still have a problem because the sample size is too small. Looking at our planet's temperature for only a couple thousand years is no different. There's the same reason we don't try to calculate support and resistance levels using 5-minute intraday bars on an investment you intend to hold for years.When viewing as little as 2000 years of data (a microscopic blink in time against the backdrop of humans occupying earth for over 100K years), it becomes clear the only thing that doesn't change is our climate changes, with or without your Chevy running. It's not as if this information is a secret and by Googling (GOOG) "Ice cap global temperatures" you can review all the government data you want along with many graphs. Some show greater variations and some not as much, but the above graph is a fair representation and takes the "hockey" out of stick. Another reason to doubt alarmists is, they have a dog in the fight. Many of the AGW critics are funded by industries negatively impacted from carbon taxes and greater regulation, and many of the most vocal alarmists depend on AGW for funding, influence and fame. If AGW becomes unimportant, a lot of scientists and activists will suddenly find themselves looking for a new line of work. For both sides of the argument, follow the money. The AGW alarmists have been at it long enough to show a record of getting it wrong. When the IPCC issues the next report, expect a lot of backpedaling from previous scares. The models are wrong (once again), and now X amount of carbon isn't nearly as nefarious as thought of just a few years ago.