Ships touching European Union shores will be obliged to record carbon dioxide emissions under a new law to help save the world from global warming, about which there is growing scepticism.

Greece, Cyprus, Malta and Poland, the home of smaller ship operators, voted against the law, which comes into force within months, Reuters reports.

Big shipping companies like Denmark's AP Moller-Maersk, the world's biggest, tend to like such laws, with Maersk calling the latest, a "pragmatic solution".

Such laws increase a big company's market share because smaller operators are forced out when they cannot meet soaring compliance costs that have sky rocketed in recent years.

Shipping accounts for three per cent carbon emissions, which could increase to 18 per cent by 2050 if regulation is not in place, according to the United Nations' agency the International Maritime Organisation (IMO). While such is not disputed, the negative effect is. The UN is the world leader in the global warming crusade.

The EU law stops short of including shipping in the EU's Emissions Trading System (ETS), the bloc's flagship tool for cutting carbon, but EU officials said it was a step in that direction, Reuters reports.

It introduces a mechanism for monitoring, reporting and checking shipping emissions as a follow-up to an October EU agreement on new targets to restrict CO2 as a precursor to UN efforts to win global regulatory pact next year.