Carbon offsets should embrace uncertainty

Carbon offset projects are a common way to compensate for emissions by funding an equivalent carbon dioxide saving elsewhere. Although the idea might seem enticing, they are constantly criticized. Very often, the criticism rightly focuses on the question of whether offset schemes can rightfully claim how much carbon they have stored.

Many suppliers of offsets have responded to this criticism by using more and more sophisticated methods for measuring carbon sequestration. This is the wrong approach, according to a new policy paper published in Science.

In the paper, the authors argue that the carbon offset market should look at the bigger picture of creating resilient forest landscapes instead.

He and his co-authors argue that buyers should stop viewing offsets as a direct substitute for reducing their emissions and instead use them as a broader commitment to address climate change by building resilient forest landscapes. This includes the communities that can protect such landscapes and in doing so, secure the efficacy of the carbon projects.

Measuring the carbon stored in forests over time is highly complex. For a carbon offset project to be viable in a traditional sense, it has to show that (1) the carbon stored is additional to what would have been stored without the project, (2) the efforts do not increase emissions elsewhere, and (3) that the storage will be intact for decades and centuries to come.

These three principles, additionality, leakage, and permanence, form the backbone of the carbon offset market today. When it comes to assessing them, a lot of weight is put on estimates of biomass and tree cover changes in combination with detailed risk analyses. However, these analyses often fall short because they only take into consideration risks that are already known.

“Many forest landscapes are subject to deep uncertainty. It’s a world of unknown unknowns. Not only do you not know the state of key parameters – you don’t even know what the key parameters for successful carbon offsets are,” says co-author Unai Pascual, research professor at the Basque Center for Climate Change, and co-Chair of the Values Assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). 

This does not mean that the carbon offset market should be abandoned altogether. Other sectors have found ways to operate under similar types of uncertainty without getting bogged down in the same type of problems.

In the paper, the scientists draw analogies to internet service providers, who agree to do their best to provide a reliable speed and stability of service, even if the actual level may fluctuate in unpredictable ways. Such a “best efforts”-approach could also be applied to the carbon offset market, according to the researchers.

“Some degree of measurement and assessment is obviously important. But spending money chasing ever more complicated or precise measurements of forest carbon change is a red herring,” says co-author Casey Ryan, professor at the School of GeoSciences at the University of Edinburgh.

The best way a carbon buyer can manage risk is not necessarily to find the project or rating agency with the most technologically sophisticated monitoring and modeling, but to look at the broader picture of whether a project is building strong, forest-friendly local economies that can withstand changes in climate, politics, social demographics and global markets. “This broader trajectory is what matters in the end, even if there is uncertainty in the short term about the precise additional carbon sequestered,” says Geoff Wells.