Global Warming Primer

Measurements of the amount of greenhouse gases in these bubbles show that the "pre-industrial" amount of CO2 in the atmosphere was about 280 parts per million (ppm), almost 100 ppm below todays value. The figure below show results of CO2 measurements of air trapped in ice cores taken at the Law Dome site in Antarctica, along with present day measurements at the CMDL Mauna Loa Observatory in Hawaii. CO2 amounts have increased about 35% in the last 200 years.

NOAA

Moreover, there is simply no skeptic papers that disagree with the scientific consensus as the now famous study by Naomi Orsekes illustrates.