But that system has been plagued with difficulties and the United Nations, which monitors it, has delayed a number of investments because of dubious emissions reductions.
BRUSSELS — Profiteering, tax fraud, theft and dubious claims of emissions reductions are just some of the problems plaguing carbon trading.
Offsets — like credits bought from programs that plant trees to absorb carbon dioxide, or that farm using methods that reduce emissions from the soil — were often seen as a dubious shortcut to real emissions reductions.
The ExxonMobil report also made the dubious assumption that carbon emissions would stay constant over time, rather than decline in response to a price on carbon.
Not only that, but while motor manufacturers have been exploiting legal loopholes and using dubious techniques to pass emissions tests, the government has failed to hold them to account - while bidding behind the scenes to allow increased emissions.
"VW appear to have been caught red-handed, but it would seem highly likely that others have also played dubious games to pass emissions tests," said Professor Alastair Lewis, an air pollution expert at the University of York.
Whether global climate change is a problem that can be solved by California is a dubious proposition one year's worth of emission growth in China is greater than California's total emissions.
Half Empty: The devil is in the details, specifically, whether scientifically sound accounting will be adopted versus self-reported emissions reductions that may include double counting and dubious claims.
The report also warns that Europe's emissions trading scheme (ETS) is a "global dumping ground" for "dubious" carbon permits created by projects around the world.
And it would allow companies to account for emissions reductions by buying "offsets", many of which are extremely dubious, or, at the very least, troublingly opaque.
