The CO2 column abundance is a challenging quantity to measure in the atmosphere because of its small global gradients. However, to gain  insight into the carbon cycle, it must be measured with unprecedented precision and accuracy. The Total Carbon Column Observing Network (TCCON) aims to do just that: it is a ground-based network of Fourier transform spectrometers designed to measure total column abundances of CO2 and other greenhouse gases in the near infrared. I will describe our measurement technique and some of the carbon cycle studies that have resulted from these measurements.