At a "summit meeting" this month they agreed to "rationalise" services in the Trans-Pacific and European trades, develop regional feeder networks, cooperate on terminals and control vessel speeds.
The CKYH Alliance brings together COSCON, "K" Line, Yang Ming, and Hanjin Shipping. In a statement they said the summit was "to strengthen the cooperation" among the alliance partners.
They said they were trying "to overcome the current challenges in the shipping industry, such as the unprecedented escalation of bunker and operation costs."
The statement went on: "Furthermore, in recognition of the importance of global environment, the CKYH Alliance also agreed to make efforts to protect the environment by reducing bunker consumption."
The alliance said it would reduce bunker consumption through "service rationalization", through "vessel speed control" to cut CO2 emissions and by using environmentally-friendly equipment.
COSCON is the container arm of the Chinese shipping company COSCO.
It has already been recognised by the US Port of Long Beach as complying with a voluntary scheme to reduce vessel speeds close to the port in order to reduce air pollution.