* Risk appetite returns, helps global equities
* Yen slips as Japan downgrades economic outlook
* Oil rebounds from recent losses, gold rises
* U.S. President's speech on budget plan on tap
(Updates market action, changes dateline)
NEW YORK, April 13 (Reuters) - Renewed investor optimism boosted global stock markets on Wednesday, while the yen fell as Japan scaled back its economic outlook due to last month's disasters.
World stocks as measured by MSCI <.MIWD00000PUS> were up half a percent for a 4.5 percent year-to-date gain. Much of the drive came from emerging markets <.MSCIEF>, which gained more than two-thirds of a percent.
Oil rose above $122 a barrel, rebounding from a two-day sell-off on worries that high prices will crimp demand, while gold notched higher on a weaker dollar.
The dollar has weakened against most major currencies this year on concerns over the huge $1.5 trillion federal budget.
U.S. President Barack Obama is due at about 1:30 p.m. (1730 GMT) to outline his plan for tackling the long-term U.S. deficit and debt in a speech in which he is expected to push for higher taxes for the rich and changes to government pension and healthcare plans. [ID:nN12216395]
The dollar, however, has firmed versus the yen since late March as Japan faces the daunting task of rebuilding after the ravaging quake and tsunamis that hit the country last month.
(Additional reporting by Angela Moon in New York; Jeremy Gaunt, Brian Gorman, Jessica Mortimer, Barbara Lewis, Jan Harvey in London, Editing by Chizu Nomiyama)