BIG shipping lines are advocating a levy on carbon emissions on shipping in an effort to tighten rules on greenhouse gas emissions, Reuters reports. Critics see this as a move to drive up environmental compliance costs to put smaller operators out of business, thus reducing competition and increasing their own market share. "To meet international shipping's decarbonisation challenge, the maritime industry needs a carbon levy, it is coming, and we should shape it," said Andreas Sohmen-Pao, chairman of BW Group at the Global Maritime Forum in Singapore this week. The comments followed closed working group discussions on the need for a levy on carbon emissions from shipping operations with other executives from other companies including Cargill Ocean Transportation, Euronav, Angelicoussis Group, Torvald Klaveness Group, Norwegian bank DNB and mining giant BHP. Maritime shipping, which represents about 90 per cent of international trade, accounts for about 2-3 per cent of global carbon dioxide (CO2) emissions. The UN's International Maritime Organisation (IMO) has a goal to cut greenhouse gas (GHG) emissions by 50 per cent by 2050. Immediate action is needed if the global shipping industry is to meet this target, the International Renewable Energy Agency (IRENA) said in a report released this week. In the absence of suitable mitigation policies, GHG emissions associated with the shipping sector could grow between 50 per cent and 250 per cent by 2050, it said. But how to achieve this remains unclear as alternatives to fossil fuels, such as biofuels and hydrogen-based solutions, remain uneconomical and require significant infrastructure investments and technological advances, the report said.