A system for maintaining a cargo in a refrigerated condition over an extended duration employs an insulated enclosure having both a cargo-enclosing portion (25) and a carbon dioxide-enclosing portion (28) separated by an insulated barrier (32). A finite amount of solid carbon dioxide is placed in the carbon dioxide-enclosing portion (28) at the beginning of the duration. By properly insulating the barrier to provide a rate of heat transfer within a predetermined range, the cargo is maintained in a refrigerated condition without replenishing the solid carbon dioxide for uniquely lengthy durations. Such durations are especially maximized by employing such enclosures in the form of cargo-carrying containers of generally rectangular shape stackable vertically atop one another and/or in close side-by-side relation to one another.
