refrigeration method changes
CO2 mostly in a hybrid system using a modest amount of ammonia is rapidly replacing CFCs and HCFC refrigerants. EU is putting such systems in places like super markets; the US is following the EU lead.
CO2 is being reestablished as a refrigerant of choice after a hiatus in its use for most of the 20th Century. It's surely nothing new. CO2 in an ammonia hybrid system can often free a company from the rigorous "process safety management" requirements of OSHA when over 10000 pounds of NH3 are in the system.