The world’s economists are falling all over themselves trying to outdo one another in raising their forecasts for U.S. and global economic growth – first the dismal science’s “cream of the crop” at the NABE (National Association for Business Economics), then the braintrust at the Federal Reserve, and now the OECD (Organization for Economic Cooperation and Development) as detailed in this report at Bloomberg.

The economy of the OECD’s 30 members will grow 2.7 percent this year, more than the 1.9 percent predicted in November, the Paris-based group said today in a report. Including non-members such as China, the global economy will expand 4.6 percent this year and 4.5 percent in 2011, compared with an average of 3.7 percent during the decade through 2006.

The projections highlight the divergence in the global economy after it emerged last year from its worst slump in more than half a century. While the economies of China and India risk overheating, indebtedness may threaten expansion in the developed world, according to the OECD, which advises its members on policy.

“A first substantive risk is related to developments in sovereign debt markets,” OECD Chief Economist Pier Carlo Padoan wrote in the report. Elsewhere, “a boom-bust scenario cannot be ruled out, requiring a much stronger tightening of monetary policy” in some countries, including China and India, he said.

Translation: If the European debt crisis that now appears to be careening out of anyone’s control doesn’t get any worse and if China is successful in reining in asset bubbles that become more dangerous with each passing week, the global economy should grow nicely.