The Clean Development Mechanism, which is supposed to offset greenhouse gases emitted in the developed world by selling carbon credits, has been “contaminated by gross incompetence, rule-breaking and possible fraud by companies in the developing world,” The Gurdian reports.

One senior figure suggested there may be faults with up to 20 percent of the carbon credits already sold. Since these are used by European governments and corporations to justify increases in emissions, the effect is that in some cases the process has added to the net amount of greenhouse gas in the atmosphere.

Most of the concern is around the CDM test of additionality – proof that a project is delivering cuts in greenhouse gases that would not otherwise have happened. A BusinessWeek article in March pointed to the same problem on a smaller scale.

Errors include “conjuring up numbers when projects on the ground failed to provide them; giving a green light to commercial projects which make no contribution to reducing greenhouse gases; and approving existing projects which cannot claim to be part of the drive to cut emissions.”