In a commitment to curb global warming, the 12-nation European Community has pledged to limit its output of carbon dioxide emissions in the year 2000 to the 1990 level.

The move Monday by EC ministers was seen as an attempt to pressure the United States into a adopting a similar pledge at a major international conference on the issue.Next week, negotiations open in Geneva on a convention aimed at curbing the release of carbon dioxide and other man-made gases that are causing a gradual increase in global temperature - with potentially catastrophic environmental implications.

Plans call for the drafting of a convention that would be ready for signing in 1992.

The United States has yet to issue a proposal on how it plans to curb its carbon dioxide emissions - produced largely through the burning of fossil fuels.

"A divided European Community would have been an excuse for the Americans not to proceed any further," said a European Community source, who spoke on condition of anonymity.

Scientists believe that if nothing is done to curb them, emissions of carbon dioxide and other heat-trapping gases could boost global temperatures 5.4 degrees by the end of the next century, the fastest rise in 10,000 years.

They call the phenomenon the greenhouse effect, and say that if unchecked it could cause sea levels to rise and deserts to spread.

About 500 scientists convened in Geneva on Monday for a 10-day U.N. conference on global warming.

A conference-ending meeting of about 80 ministers is expected to draw several heads of government, including British Prime Minister Margaret Thatcher and French Premier Michel Rocard.

The United States has sent a lower-level delegation.

The EC's position to maintain its overall output of carbon dioxide at 1990 levels in 2000 matches a pledge by Japan.

The EC executive commission will work out quotas for each member nations by the end of this year.