Global trade is expected to stumble over economic hurdles in China and Brazil. Reuters/Toru Hanai

The World Trade Organization shaved half a percentage point off its global trade projections for 2015, after a disappointing first half of the year left export growth weakened across the developing world. World merchandise trade volume is expected to rise 2.8 percent for the year, down from April projections of 3.3 percent. The WTO also revised its 2016 projections to 3.9 percent, from 4.0 percent.

Slumping demand from China and Brazil have put a drag on trade, in addition to falling energy and commodity prices and financial market turbulence. Uncertainty around the U.S. Federal Reserve's eventual benchmark interest rate hike also weighed on markets, the WTO said.

Global trade fell in the first quarters of 2015. World Trade Organization

The heaviest downward revisions came from Asia, which saw WTO export growth estimates cut roughly 40 percent and import growth nearly by half. As China pivots to an economy led by domestic consumption, import volume has fallen. Chinese iron and steel imports, for example, were down 10 percent year-over-year. Though Beijing puts official GDP growth at 7 percent, business leaders have painted a gloomy picture of Chinese commerce.

Flagging Chinese demand for imports has been felt globally. World Trade Organization

South and Central America also played into the WTO's revised forecasts, with imports expected to drop 5.6 percent in 2015, down from a -0.5 percent projection earlier this year, with Brazil's ongoing economic turmoil playing a major role. South America's largest economy has been destabilized by steeply rising inflation and corruption scandals in major industries.

The downbeat forecasts continue a four-year post-recession trend in which global trade growth nearly matches global GDP growth -- a change from the 1990s and early 2000s, during which global trade growth roughly doubled economic growth.