DAVOS, Switzerland (Reuters) -- World business leaders welcomed President Bush's acknowledgment of climate change as "a serious challenge", but called on Wednesday for long-term emissions standards to help them plan.

While supporting the White House nod to alternative energies such as ethanol, wind, solar and nuclear power, corporate executives meeting at the Swiss ski resort of Davos said they wanted Washington to lock in stricter U.S. emissions standards.

Bush declined in his annual State of the Union address to support mandatory caps on heat-trapping carbon gases that big U.S. companies such as General Electric Co. have pushed for, instead backing new technologies to cut the amount of gasoline used in the United States. But he did call on Americans to cut their gasoline use by 20 percent over a decade, mostly through a nearly five-fold increase in use of home-grown fuels such as ethanol, and urged tighter vehicle fuel efficiency standards.

"It is a good step, but we need to take many more," Duke Energy chief executive James Rogers said on the sidelines of the World Economic Forum meeting, where climate change is dominating talks among some 2,400 global movers and shakers.