While Britain's vote in June to leave the European Union "will affect the supply chain for many years to come," China's slowdown – especially in fixed asset investment – is more alarming, says Cliff Waldman, director of economic studies for the Manufacturers Alliance for Productivity and Innovation Foundation.

"It is broader, deeper and more difficult than people expected," Waldman said. As the country shifts from a manufacturing economy to a services economy, "China is a risk-laden story."

Economic stagnation in China will likely continue to stifle GDP here and globally, according to Waldman in the MAPI Foundation's most recent quarterly Economic and Manufacturing Outlook. It also is more troubling than Brexit, which is a crisis, but "not the crisis of 2008, when on a daily basis we thought we were failing apart," Waldman said.

Brexit, however, is contributing to overall sluggishness in the U.S. and around the globe, and the impact on manufacturing from Brexit, China and softness in energy and other commodities is severe.

The manufacturing sector contracted in August following five consecutive months of expansion, while the overall economy grew for the 87th consecutive month, according to supply executives in the latest Manufacturing ISM Report on Business. The August PMI was 49.4 percent, a decrease of 3.2 percentage points from the July reading.

MAPI again lowered its GDP growth forecast – now 1.6 percent for 2016 (down from 2.2 percent in the first quarter) and 2.4 percent for 2017 (down from 2.6 percent in the first quarter).

The organization more significantly reduced its manufacturing growth – now 0.2 percent for 2016 (down from 1.1 percent in 1Q) and 1.6 percent for 2017 (down from 2.4 percent in 1Q).

As global sluggishness persists, "we are in a strange time," Waldman said. "The world's a very difficult place right now and it's hurting your businesses at the moment."