The paradigm that winter is a dormant period of soil biogeochemical activity in high elevation or high latitude ecosystems has been amply refuted by recent research. Carbon dioxide (CO2) released from cold or snow-covered soil is a substantial component of total annual ecosystem carbon fluxes. Recent investigations have shown that the late-winter/early-spring transition is a period of high biogeochemical activity. However, little is known about the temporal dynamics of CO2 from the snowpack itself during periods of snowmelt. We present a case study of three snowmelt events at a high-elevation site in northern Arizona during which we measured changes in CO2 concentrations and fluxes above the snow and within the soil profile, and characterized the soil physical environment and site meteorological variables. We show that large pulses of CO2 were emitted to the atmosphere during snowmelt, and we present evidence that these pulses came from CO2 stored in snowpack. Earlier and more frequent snowmelts worldwide caused by climate change have the potential to alter the timing of release of CO2 from land to atmosphere.