Several Republican senators expressed skepticism yesterday that international negotiations on the Kyoto climate change treaty this November would produce an agreement the Senate would ratify. At a Senate hearing, Sen. Frank Murkowski (R-Alaska) said the treaty would unfairly burden the American economy by forcing reductions in the use of oil and coal. Sen. Chuck Hagel (R-Neb.) said the cutbacks in carbon-dioxide emissions called for in the treaty were not attainable, and he pointed to recent research by James Hansen of NASA’s Goddard Institute for Space Studies that suggests it could be more effective to concentrate first on cutting greenhouse gases other than CO2. Frank E. Loy, undersecretary of state for global affairs, said the Clinton administration is determined to make the agreement cost-effective and rejected calls that it be abandoned. Loy will head the U.S. delegation to negotiations on the agreement in November in The Hague, where a number of contentious issues are on the table.