Some background on CO2 systems. On the one hand, great, because CO2 has a GWP of 1 as you point out. On the other, the operating pressures are much higher than

Some background on CO2 systems. On the one hand, great, because CO2 has a GWP of 1 as you point out. On the other, the operating pressures are much higher than other conventional refrigerants (80+bar vs 20bar). Because of this high pressure the components are more expensive, and you don't see any field installs of refrigerant lines like in a mini-split setup. Instead the CO2 systems typically come as factory sealed air-water systems.