This study explores a new concept of Martian differential absorption lidar operating at the 2-m CO2 absorption band for its atmospheric CO2 and pressure observations. For the considered system, closely-spaced two or more wavelengths are selected so that environmental impacts such as surface reflection, atmospheric scattering, and absorptions from other trace gases on the lidar return signals are very similar for all selected wavelengths, but the difference in CO2 absorption is substantial. Thus, Martian CO2 amount and air pressure could be retrieved from the measured CO2 differential absorption optical depth at the selected wavelengths. Simulations based on Mar’s environmental conditions and technically available lidar systems show that lidar returns from the surface with horizontally 5 km averaging could have sufficient signal strengths that allow air barometry and CO2 amount measurements with a noise induced random error (NIRE) smaller than 1% when the optical depth due to dust scattering, the dominant scatter in the Martian atmosphere, is 3 or less. In the presence of moderate dust aerosol loads and with the optimal selection of offline and online wavelengths, atmospheric CO2 and pressure profiles could also be retrieved from the surface up to ~10 km altitude with the NIRE smaller than 1% for a horizontal resolution of 100 km and a vertical resolution of 100 m during night or 400 m during day. When a second online wavelength is use, the lidar would provide invaluable measurements of Martian CO2 and pressure fields from surface up to about 13 km altitude.