According to Professor McKinnon, the United Nations recently estimated that each Hong Kong resident produced 5.5 tonnes of carbon dioxide annually. Its transport sector contributed 24 per cent of carbon dioxide emissions. In the United States, each person produced 19.8 tonnes of carbon dioxide, while in the mainland each person produced 3.2 tonnes and Britain 9.4 tonnes. Professor McKinnon said Britain hoped to cut carbon dioxide emissions by 60 per cent by 2050.

In the mainland, the central government has demanded that all regions reduce carbon emissions and energy use by 20 per cent within five years. It will then be up to local authorities to ensure that legislation is enforced, even in areas where environmental awareness is lacking.

However, there is some resistance to the move, according to a mainland academic.

Geng Yong, associate director of the Institute for Eco-Planning and Development at Dalian's University of Technology, said: 'A large number of firms, especially SMEs, regard 'green' as non-economic, and environmental protection as strong reactive action.'

The institute is participating in an eco-industrial park planning programme for Dalian. The project aims to integrate solid waste, energy and water management systems so that products can be recycled and re-used by other companies on site.

Professor Geng is designing an information exchange platform to inform companies at the industrial park about which recycled products they can buy and sell. Nationwide, 26 out of the mainland's 6,600 industrial parks were chosen to participate in the programme.

The professor said he believed the implementation of green supply chain management in the mainland would require top-level management support, collaboration among different departments that would interact with suppliers, better communication with suppliers about environmental issues and performance expectations, higher environmental awareness among employees and ISO 14001 environmental certification.

With the shift towards outsourcing production to Asia, products manufactured in the mainland have to meet stiffer international environmental standards.

A Dalian-based motor company has set up two productions lines, one for producing high-quality vehicles for export to countries with tighter environmental standards and another for the cheaper domestic market.

Avnet Electronics Marketing has based most of its manufacturing sites in Asia, especially in the mainland.

In the past few years, Avnet has made bottom line cost savings through cutting energy consumption and packaging, transport, recycling, disposal and hazardous material management costs, and increasing recycling of corrugated material and reusing plastic trays.

Louis Lam, vice-president of operations, Asia-Pacific at Avnet Asia, said: 'Green procurement policies, brand identification and cost savings are driving our industry to increase our green logistics efforts.'

Also in the mainland, the potential for rail freight is far greater, particularly as industry moves further inland, extending the haulage distance, according to K.Y. Leung, forum chairman and senior programme director of the University of Hong Kong's School of Professional and Continuing Education.

The mainland's Ministry of Railways, he said, had started work on a high-speed railway line for passenger traffic from Guangzhou to Wuhan, which would free up the existing railways for freight trains. A line from Beijing to Shanghai was being considered, he said.

He also said that in a city the size of Hong Kong, it would not be economically viable to take freight off the roads in favour of the less-polluting railways as delivering freight door-to-door still required the use of trucks.

The conference also heard that biodiesel trucks had been generating a great deal of interest because they emitted 52 per cent less greenhouse gases than regular trucks, according to research last year by the Conservation of Clean Air and Water in Europe, a study group established in 1963 by leading oil companies.

However, a quarter of arable land in Europe would have to grow biofuels such as grape seed and palm oil to meet energy needs, Professor McKinnon said.

He also said that along the global supply chain, the majority of carbon was emitted during the production process, meaning logistics firms would have to work hand-in-hand with their suppliers to reduce the industry's carbon footprint.

Recently there was an attempt by some major retailers in Britain to put carbon labels on their products to indicate how much carbon dioxide was emitted during the production, transport and disposal stages.

The problem, Professor McKinnon said, was it involved a considerable amount of time and investment to work out and monitor how much carbon dioxide was emitted in the supply chain.