A UK government quality mark will help IT purchasers choose suppliers with valid carbon offset schemes instead of untrustworthy ones, when it arrives later this year.

Carbon offsetting is the practice of defraying one's own carbon emissions by paying for schemes to produce reduced carbon emissions matching what you are going to emit. The schemes are typically located in under-developed countries and involve tree plantations or low-emission energy generation. The idea is that it doesn't matter where carbon is taken out of the atmosphere so long as it is taken out somewhere.

The government believes that direct carbon emission reduction is preferred, but that offsets are viable when direct reduction is impractical. Suppliers like Dell use carbon offset purchases to render use of their products carbon-neutral.

However, many carbon offset schemes have been shown to be untrustworthy because their results can't be verified, or whatever they might achieve in the future by way of tree plantation would have been achieved by natural vegetation anyway.

The government has responded to these carbon offset doubts by consulting on developing a code of practice. This has produced a report with recommendations and the code will be based on them.

Joan Ruddock, minister for climate change, biodiversity and waste at Defra, said: “People need to be sure that when they buy an offsetting product the emission reductions are actually taking place, which is why we are developing this code, which will be accompanied by a quality mark for accredited products."

Offsetting providers will decide themselves whether to seek accreditation for some or all of their schemes.

There are two broad types of traded carbon offsets. Certified Emission Credits (CER) are credits produced, vetted and regulated under the auspices of the UN's Kyoto protocol for climate change and an equivalent EU scheme. Many of the 166 contributors to the DEFRA consultancy pressed for the inclusion of the less-tightly controlled Voluntary Emission Reductions (VER) from non-regulated markets.

The draft code of practice excluded VERs. The DEFRA analysis states: "47 respondents, especially businesses and NGOs/charities, made comments to the effect that, if the code was to deliver the stated aims, VERs should be included within in it."

When the code arrives in the autumn, companies that already carbon-offset, like Dell, will have to decide whether to seek UK accreditation for their offset schemes. Businesses and other organisations buying IT products and services may decide to make offset scheme accreditation a condition of purchase. Certainly providers of accredited schemes can be relied upon to press home the greater trustworthiness of such accreditation.