An emergency ordinance is an ordinance which in the judgment of the council is necessary for the immediate preservation of peace, health or safety. Every such ordinance shall contain, as part of its title, the words, "and declaring an emergency"; and in a separate section, herein called the emergency section, shall declare the emergency. The council shall vote on the emergency section separately, and must adopt the section by a vote of at least four-fifths of all the members of the council, which vote shall be by yeas and nays and be entered in the journal. An emergency ordinance shall take effect upon publication unless it specifies a later time.