Field deployable instrumentation is paramount to accurate global carbon models. Successful development of a field deployable CO2 isotope spectrometer will bolster NASA's capabilities in their Global Climate Change program. Although a majority of NASA's earth based measurement platforms are satellites, terrestrial measurement systems both validate remote measurements as well as fill in the gaps of understanding. Information on carbon sources and sinks as well as fluxes of carbon that arise from precision δ13CO2 measurements that this proposal will offer, can also be incorporated with the direct public service from NASA's Earth Observatory program. NASA's current CO2 mappings are not specific to isotopic distributions. Widespread measurements of carbon dioxide isotope ratios can help discriminate anthropogenic from biogenic CO2 sources on a global and local scale. The technologies developed from this proposal extend beyond δ13CO2 for atmospheric CO2 measurements. The methodology of using the large current tuning range of VCSELs to access isotopic lines of nearly identical ground state energies can be investigated and applied to various other isotopic species of interest to NASA. Besides NASA, there are widespread needs in the public research sector for atmospheric species monitoring. With global warming at the forefront of environmental concerns, both academic and research institutions need reliable and affordable δ13CO2 instrumentation to use in support of or as the basis of their research. Like NASA, the atmospheric research communities have interest in other isotopic measurement instrumentation to measure δ18O for O2, CO2 and N2O as well as δ13C measurements on methane. These communities would include institutions such as NCAR, NOAA, universities, and national labs.