Travel and tourism is one of the largest industries in the world and is a large contributor of greenhouse gas (GHG) emissions. Religious tourism is a fast growing sector within the tourism industry. Pilgrimage to Mecca, Hajj, is one of the oldest and largest religious tourism events in the world drawing 2.79 million participants from all around the world in 2011. Managing an event at such scale poses many challenges on multiple fronts, not the least are the environmental management of its impacts. Quantifying the environmental impacts of the event is a key element in setting up proper and effective environmental management programs. This article uses life cycle methodology to assess the Global Warming Potential (GWP) from the main activities of the Hajj event. On average each pilgrim contributes 60.5 kg CO2-eq per day as a result of transportation, hotel stay, meals and waste management. Long haul air travel is the largest contributor of greenhouse gases, followed by lodging then food with each accounting to 60%, 18% and 13%, respectively. Infrastructure provision, upstream emissions and aviation higher altitude emission effects account to more than 50% of the total GWP of the event. The potential of applying the concept of carbon neutrality by extending preservation principles built-in the traditional Hajj rituals is also discussed.