As measured directly by thermometers and as documented by historical records and other biological indicators (including tree rings, corals, and ice cores) the temperature on Earth has increased rapidly in the past 140 years. This is paralleled by an increase in greenhouse gases, including carbon dioxide.
SOURCES: CO2 data from NOAA Earth System Research Laboratory http://www.esrl.noaa.gov/gmd/ccgg/trends; temperature data from IPCC Third Assessment Report “Climate Change 2001” http://www.ipcc.ch/pdf/climate-changes-2001/synthesis-spm/synthesis-spm-en.pdf and Nasa Goddard Institute for Space Studies http://data.giss.nasa.gov/gistemp/graphs_v3/.