High-resolution carbon dioxide concentration record 650,000–800,000 years before present Figure 1 shows concentrations for 650,000 to 800,000 years ago, the the values for CO2 concentration ranges from 180 ppm to 260ppm (We're currently at ~380 ppm).
Figure 2 shows a strong correlation between global temperature and CO2 levels.
And this "Web Focus" for the EPICA project (which produced the above paper) seems to be freely available.
Another study, Warming world altering thousands of natural systems, has found:
Most (about 90% of the >29,500 data series, P << 0.001) changes in these systems at the global scale have been in the direction expected as a response to warming. Ninety-five per cent of the 829 documented physical changes have been in directions consistent with warming, such as glacier wastage and an earlier spring peak of river discharge. For biological systems, 90% of the approx 28,800 documented changes in plants and animals are responding consistently to temperature changes (mostly by means of earlier blooming, leaf unfolding and spring arrival).
Attributing physical and biological impacts to anthropogenic climate change,
Cynthia Rosenzweig, et.al. Nature 453, 353-357 (15 May 2008)
Those are changes that have been documented since 1970. Global Warming is real, it is happening right now, and we need to deal with it Now.
(Alas the second paper may not be freely available.)