According to the World Economic Forum, if shipping was a country, it would be the sixth-largest polluter in the world.
That would leave shipping producing as much as 17% of global carbon dioxide emissions in 2050.
The challenge is particularly acute because the choices shipping companies make now will play out over the next 30 years.
Little headwaySince the IMO set its target, many of the world's largest shipping companies have made ambitious pledges to slash their emissions over the next three decades.
"Shipping companies are failing to push for the critical technologies required to reduce their carbon footprint," according to CDP.