Media forecasters continue to be spooked by the bad end to 2008 and poor start to 2009.

The latest is GroupM, which today revised its 2009 outlook from glum to gloomy, both on a global level and in the U.S. particularly.

The report, issued this morning, predicts that global advertising spending will fall 4.4 percent this year, to $425 billion. That’s a big change from GroupM’s prediction in December, when it said media spending would fall 0.2 percent this year, to $458 billion.

GroupM also revised its already dreary U.S. outlook for 2009 and beyond, forecasting that spending will fall 4.3 percent this year and 6.8 percent in 2010, when some have predicted the recession will begin to lift.

In December, GroupM had forecast a 3 percent U.S. decline this year, to $157 billion.

Last year global ad spending was up 3 percent, according to GroupM, but when adjusted for consumer price inflation, spending actually dipped a bit.

“The 2008/2009 period is now a more serious advertising recession in scale, duration, and relative to the global economy, than the extraordinary 5.1 percent real-terms post-dotcom global advertising correction of 2001,” said London-based GroupM Futures Director Adam Smith in a statement.

The steeper decline in 2010 U.S. advertising is being blamed on marketing budgets that have been cut during this recession.

Rino Scanzoni, GroupM’s New York-based chief investment officer, said the U.S. government’s federal stimulus package will have little impact on ad spending because it will not boost consumer spending in the face of high unemployment and a weakened housing market.

“Any optimism we feel about the U.S. this year is expected to be mitigated by a further spending decrease in 2010,” Scanzoni said in a statement.

GroupM is hardly the only forecaster worried about this year, coming off a 2008 in which just one medium, cable television, saw spending rise compared to the previous year, according to Nielsen Monitor-Plus.

ZenithOptimedia issued a revised forecast in December predicting that U.S. ad spending will fall 6.2 percent this year, though it predicted slight growth in 2010.

And eMarketer revised its online forecast late last year, still calling for growth in 2009 but cutting its prediction from 14.5 percent to just under 9 percent.