The UK’s 100 biggest companies have been ranked according to their greenhouse gas emissions and levels of transparency.

The Environmental Investment Organisation (EIO), a UK non-profit research body, has created the ET UK 100 Carbon Ranking, spotlighting the best and worst of Britain’s top businesses.

To view the Top 100 UK firms' carbon rankings click here

Leading the ET UK 100 are insurers Amlin and financial services giant Aviva, with carbon intensities of 1.21 and 1.36 respectively (MtCO2e/$M turnover). Others ranked highly are British broadcasting giants BSkyB, whose intensity of 6.69 place it 4th, followed by energy services company AMEC, at 8.31.

The EIO has adopted a strict methodology based on complete disclosure of Scope 1 and 2 emissions according to the Greenhouse Gas Protocol, the internationally recognised standard for emission reporting.

Only companies that publicly disclose and also independently verify their emissions data made it into the top category. Among the ET UK 100 companies, although 66% publicly disclose their data, only half of those are also independently verifying their reported emissions. With the exception of BP and GlaxoSmithKline, whose data was defined as incomplete, all companies with a market value over $100bn publicly disclose their complete emissions data.

Sam Gill, Operational Director of the EIO, said "Given that each company listed in the ET UK 100 is one of the biggest in Britain, if not the world, keeping this information out of the public domain is no longer excusable."

Coming bottom of the UK's biggest 100 companies is Randgold, a gold-mining company operating primarily in West Africa. They do not make their data publicly available, despite market competitors BHP Billiton and Xstrata both disclosing and verifying their emissions (ranking 31 and 34 respectively).Randgold's inferred emissions intensity - benchmarked against their highest disclosing sectoral competitor - is 3,477.34. Second from bottom is global cruise company Carnival, followed by offshore drillers Ensco, utilities company Pennon and the financial giant, Standard Chartered. All of these five are part of the bottom 13% of companies that do not disclose any emissions data.

Sam Gill added, "This shows the massive difference in attitude among Britain's top corporations. The rankings show that it’s less about what industry a company’s in and more about individual attitudes towards transparency. How can Shell and BP be at opposite ends of the table, or Lloyds and Standard Chartered?”

The ET UK 100 is the first in a series of Carbon Rankings, where the largest companies world wide will be covered through the forthcoming ET Global 800, Europe 300, North America 300, Asia-Pacific 300 and BRICS 100.

The EIO wants to see its rankings creating downward pressure on emissions across the world. The ET Carbon Rankings make up the first phase of the Environmental Tracking concept.

The EIO will use them to create a series of tradeable indexes, to be launched later this year. The ET Carbon Indexes are designed to lower corporate emissions by influencing a company’s share price, giving the investment community a tool to encourage transparency and emission reductions on a global scale.

Tony Greenham, Head of Finance and Business, New Economics Foundation, said “It’s a very sound approach. You're pushing up the cost of capital for carbon inefficient companies and lowering the cost of capital for the carbon efficient companies, and I think that's a simpler and potentially very powerful mechanism."

Michael Gill, the EIOs founder and Chairman, said, “It’s been a tough 15 year journey to get to this point.

It seems that finally the world is willing to take a serious look at our proposal for a market based incentive using the investment system and index funds. It completely bypasses the political log jam to be found throughout the world. Time is short and this is doable if the right people can be pressured into responding positively.”