SINGAPORE-based container carrier APL said it's on course to reduce a key carbon exhaust measure from its global shipping operations by 30 per cent within three years.

The shipping line said an influx of new vessels, running at reduced speed, puts the target within reach.

APL said that by 2015, its fleet will produce 130 grammes of carbon exhaust for every TEU of cargo transported one nautical mile. That would be a 30 per cent reduction from emission levels in 2009, when outside auditors first calculated APL's carbon footprint.

"We're changing the profile of our fleet with larger, more efficient ships that will significantly curb exhaust emissions," said APL president Kenneth Glenn. "It's the most effective way we know to make global trade environmentally sustainable."

APL said it will deploy 32 new vessels in the next three years, which will be significantly more fuel efficient than its existing fleet, resulting in reduced emissions. What's more, the ships will run at less than full speed, further curbing exhaust.

The first two of the new vessels, each with 10,000 TEU capacity, arrived last December and two more are due this month.

APL said it is undertaking additional steps to curb carbon exhaust emissions including optimising vessel trim, speed and routing; improving maintenance on vessel hulls to reduce drag in the water; and upgrading cargo handling equipment at APL terminals.

Carbon emissions act as a shield that traps heat in the earth's atmosphere and it's believed that the resulting greenhouse gas effect contributes to global warming. According to industry figures, international shipping produces 2.7 per cent of global greenhouse gas emissions. Container shipping is estimated to be responsible for about 25 per cent of that amount.