During the last decades, the Italian Alps were characterized by a very high rate of agricultural abandonment that mainly affected small farms. The remaining farms, especially in the dairy cattle sector, moved towards increasing size, intensified production and abandonment of traditional summer grazing of the herds in high altitude pastures. The aim of the study was to estimate the carbon footprint (CF) of cow milk production in the Italian Alps, comparing the traditional farming system based on summer grazing in the highlands with the emerging more intensive systems. Moreover, a sensitivity analysis was performed to investigate the variations in the outcomes of different allocation methods and of different scenarios of land use change (LUC) emissions for soybean production. A group of 32 dairy farms was analyzed in a “cradle to farm gate” life cycle assessment (LCA); 9 of them transferred the whole herd including lactating cows to the high altitude pastures for three months in the summer season (Summer Grazing = SG) while the remaining 23 (no Summer Grazing = noSG) maintained their lactating cows in the valley barns all over the year. On average the farms had a small herd size (54 ± 61 lactating cows) but a high stocking rate (3.7 ± 2.0 Livestock Unit ha−1). The average milk production was 6206 ± 1892 kg FPCM cow−1 year−1 with a huge difference between the two groups (7017 ± 1445 kg FPCM cow−1 for noSG and 4132 ± 1184 for SG). NoSG farms had also higher feed efficiency than SG ones. The CF values obtained in the baseline scenario were 1.55 ± 0.21 and 1.72 ± 0.37 kg CO2-eq. kg−1 FPCM for, respectively, noSG and SG farms.