As day broke on Saturday, delegates in Marrakech, Morocco, reached an 11th-hour agreement on the rules for implementing the Kyoto Protocol on climate change. The agreement, which was the culmination of a two-week conference and four previous years of tough negotiations, mandates an average global reduction in greenhouse gas emissions of 5.2 percent from 1990 levels and paves the way for ratification. Although some critics claimed the protocol had been watered down to an unacceptable degree, others said the agreement represents an important first step to control climate change. Many industrial nations have signaled their intent to ratify, but the Bush administration is standing firm on its decision to pull out of the accords, even with the U.S. Energy Department reporting on Friday that U.S. carbon dioxide emissions jumped 3.1 percent in 2000, bringing the nation’s total emissions increase since 1990 to nearly 14 percent.