Geothermal heating and cooling from a depth of 10–3′500 meters have considerable decarbonization potential but understudied life-cycle environmental impacts. We quantified the life-cycle impacts of six heating and cooling configurations from shallow to medium-depth geothermal wells with connected, decentralized heat pumps and district heating and cooling in the State of Geneva. Shallower systems with connected heat pumps have better environmental performance than systems with district heating, whereas shallow systems with free cooling perform best for cooling. These environmental impacts are lower than those of fossil fuels, except for mineral resource scarcity, especially with decentralized heat pumps and free cooling.