• by Joe Mandese  @mp_joemandese, August 2, 2016

WPP’s GroupM unit this morning issued a downward revision for 2016 worldwide ad estimates and forecast an equally tepid outlook for 2017.

Despite a low single-digital expansion in the world’s ad economy, GroupM predicted the global economy for all marketing expenditures would surpass $1 trillion for the first time in 2017.

The estimates, which come from the latest edition of its “This Year, Next Year” report, call for global ad spending to expand 4.0% to $529.1 billion. That’s a downward adjustment of half a percentage point from the 4.5% expansion GroupM forecast in its last outlook issued in December 2015.

Conversely, GroupM upgraded its estimates for the U.S. ad economy, which it now expects will expand 3.1% to $178.7 billion this year, up from an expansion of only 2.7% it forecasted in December 2015.

While 2017 -- a nonquadrennial year missing the incremental effects of the Olympics and the U.S. presidential elections -- is projected to be equally tepid, with the world ad economy expanding 4.3% and the U.S.’s rising 3.0%, GroupM nonetheless projects marketing services spending will become a trillion-dollar economy in 2017.

Interestingly, GroupM, which is headquartered in the U.K., said there has been “no tangible evidence of a Brexit effect in macro indicators nor budgeting decisions” that would impact its advertising estimates.