World merchandise trade volumes are now expected to rise by only 1.2% in 2019, substantially slower than the 2.6% growth forecast in April.
The projected increase in 2020 is now 2.7%, down from 3.0% previously.
Economists caution that downside risks remain high and that the 2020 projection depends on a return to more normal trade relations.
Trade conflicts pose biggest downside risk to the forecast.
Trade-related indicators signal worrying trajectory.
Disorderly Brexit could have a significant regional impact, mostly confined to Europe.