Because there is no universally accepted way of calculating someone's carbon footprint, dozens of carbon calculators have sprung up on the Internet in the past few years creating confusion and inaccurate information. In addition, accepted frameworks for tracking industry carbon emissions rely on "tiers'' of increasingly broad scope. Tier one generally includes emissions by the company's own activities, such as burning gasoline in fleet vehicles or natural gas in its facilities. The second tier boundary expands to include emissions from electricity and steam purchased by the company. Tier three includes all other emissions, including the entire supply chain of goods and services.

In practice, most companies reporting their greenhouse gas emissions opt to use only tier one or the tier two boundary. To put the implications of this boundary decision into context, Carnegie Mellon researchers H. Scott Matthews, Chris T. Hendrickson and Christopher L. Weber, have developed a new method that estimates the amount of greenhouse gas emissions across all tiers of the entire supply chain for all industries.

"By far, most companies are pursuing very limited footprints — toe prints really — instead of comprehensive ones," said Matthews, an associate professor of civil and environmental engineering and engineering and public policy.

The City of London has established the UK’s first low emissions zone, imposing charges on heavy polluting trucks in an attempt to clean up air quality in and around the capital.

London currently suffers the worst air pollution in the UK and some of the poorest in Europe. Poor air quality worsens asthma and also causes the premature death of over 1,000 people each year. The most recent survey of Londoners, carried out by Ipsos Mori, found that 72 per cent of Londoners are worried about pollution from traffic exhaust fumes.

The Low Emission Zone is the most effective way of quickly reducing pollutants that are among the most harmful to human health. It is estimated that by 2012 the Low Emission Zone will deliver reductions of around 16 per cent in the area of London where the air quality exceeds European Union pollution objectives, and will deliver over £250m of health benefits.

Housing and Planning Minister Yvette Cooper announced details of the housebuilder who will build England's first eco-village.

Barratt Developments PLC has been selected by English Partnerships, the Government's National Regeneration Agency, as the preferred developer to create a new community at the site of the former Hanham Hall Hospital near Bristol. Homes on the site will meet the Government's most exacting eco standard - Level 6 of the Code for Sustainable Homes.

Hanham Hall was the first site identified under the Carbon Challenge, being run by English Partnerships as part of the Government's commitment to tackle climate change. The Challenge will deliver zero carbon homes and communities well in advance of this becoming mandatory 2016, and help the housebuilding sector demonstrate that the targets are feasible and can be commercially viable.

As well as zero-carbon homes this ground-breaking project will create eco lifestyles. It will hand over a listed building to community use, capture rainwater and include sustainable drainage, farmers' shops, a car club and bicycle storage.