Wal-Mart has announced an initiative that aims to cut 20m metric tonnes of greenhouse gas emissions from its international supply chain by 2015, a figure that represents one-and-a-half times the company's estimated global carbon footprint growth over the next five years.

According to the US-based retailer, the target is the equivalent of removing over 3.8m cars off of the road every year.

'Energy efficiency and carbon reduction are central issues in the world today,' said Mike Duke, CEO and president of Wal-Mart. 'We've been working to make a difference in these areas, both in our own footprint and our supply chain. We know that we have an opportunity to do more and the capacity to do more.'

The footprint of Wal-Mart's global supply chain is many times larger than its operational footprint, and therefore represents a more impactful opportunity to reduce emissions, the group said.

Collaborations took place with the Environmental Defence Fund to develop the project, with other external advisors including PricewaterhouseCoopers, ClearCarbon, the Carbon Disclosure Project and the Applied Sustainability Centre at the University of Arkansas.

Three main categories make up the programme to reduce greenhouse gas emissions:

- Selection: The group will focus on product categories with the highest embedded carbon, ensuring the project team focuses on categories that have the greatest opportunity for reductions.
- Action: For a project to be included as part of the group's goal, it must reduce greenhouse gases from a product in either sourcing or raw materials, manufacturing, transportation, customer use or end-of-life disposal. Wal-Mart must demonstrate that it had a direct influence on the reduction.
- Assessment: Suppliers and Wal-Mart will jointly account for any reductions, with a quality assurance review of those claims carried out by ClearCarbon.

'Like everything we do at Walmart, this commitment ends up coming down to our customers,' Mr Duke added. 'Reducing carbon in the life cycle of our products will often mean reducing energy use. That will mean greater efficiency and, with the rising cost of energy, lower costs, making our business stronger and more competitive. And, as we help our suppliers reduce their energy use, costs and carbon footprint, we'll be helping our customers do the same thing.'