A little information is a dangerous thing. A lot of information, if it's inaccurate or confusing even more so. This is a problem for anyone trying to spend or invest in an environmentally sustainable way. Investors are barraged with indexes purporting to describe companies eco-credentials, some of dubious quality. Green labels on consumer products are ubiquitous, but their claims are hard to verify. The confusion is evident from The New Scientists' analysis of whether public perception of companies' green credentials reflect reality. It shows that many companies considered "green" have done little to earn that reputation, while others do not get sufficient credit for their efforts to reduce their environmental impact. Obtaining better information is crucial, because decisions by consumers and big investors will help propel us towards a green economy.

At present, it is too easy to make unverified claims. Take disclosure of greenhouse gas emission, for example. There are voluntary schemes such as a Carbon Disclosure Project, but little scrutiny of the figures companies submit, which means investors may be misled.

Measurements can be difficult to interpret, too, like those for water use. In this case, context is crucial: a little from rain-soaked Ireland is not the same as a little drawn from the Arizona desert.

Similar problems bedevil "green" labels attached to individual products. Here, the computer equipment rating system developed by the Green Electronics Council show the way forward. Its criteria come from the IEEE, the world's leading, professional association for technology.

Other schemes, such as the "sustainability index" planned by US retail giant Walmart, are broader. Devising rigorous standard for a large number of different types of product will be tough, placing a huge burden on the academic-led consortium that is doing the underlying scientific work.

Our investigation also reveals that many companies choose not to disclose data. Some will want to keep it that way. This is why we need legal requirements for full disclosure of environmental information, with the clear message that the polluter will eventually be required to pay. They market forces will drive companies to lean up their acts.

Let's hope we can rise to this challenge. Before we can have a green economy we need a green information economy—and it's the quality of information, as well as its quantity, that will count.