One of the most common tradeoffs I’ve seen when organisations face (or individuals) when their carbon accounting is maximising “coverage”, or the amount of their emissions covered by their accounting, versus maximising “accuracy”, or the precision of the carbon measurements for individual categories. In some cases, there is no tradeoff - particularly as more and more innovative products and services are built in this space, it becomes easier to get accurate measurements across a wide swath of categories of emissions. That being said, we’re still early enough in the development of carbon accounting tools and standards that most organisations will have to make tradeoffs here, because of cost, time, or knowledge constraints.
A brief example: A solo tech consultant might consider their office space, food consumption at work, and equipment used as the main areas to track when doing carbon accounting. While there might be relatively accurate data on the carbon footprint of a Macbook, for example, it might be harder to find accurate data on the exact impact in tons C02 equivalent of the specific banana that they bought today at the grocery store in Amsterdam, nor would it be a great use of this person’s time to do individual calculations for every different type of food they ate. In this case, assigning a more generic value to bananas or even just looking at each meal as a vegetarian, vegan, or meat-based meal (with generic emission calculators for each) would be much easier. If we spend the time to get more accurate with individual data points, we lose the time and perhaps ability to get more coverage of our carbon footprint data.
The argument for accuracy
Ultimately, in an ideal world we want our carbon accounting to be as accurate as possible, so as to give the most actionable information and benchmarks to stakeholders, and enable the most impactful reduction and offsetting plans.
In principle, it’s also important to acknowledge and show that the same product can have quite varying levels of environmental impact, depending on the context in which it’s consumed. For example, a banana eaten straight off the plant will have a lower overall carbon footprint than the banana in an Amsterdam grocery store - the transportation-related emissions are dramatically different. It’s important to incorporate this variation into our calculations as best we can.
There are also current and future regulations to consider. When doing carbon accounting, accuracy can also be enforced and scrutinised, so there will be external pressures to maximise accuracy, in some cases.
Finally, when showing carbon footprint information to consumers, accuracy is particularly important. Ethically, one should be transparent and make best efforts around the accuracy of carbon footprint numbers when consumers are using this information to make purchases. We don’t want to risk greenwashing!
The argument for coverage
This all being said, getting truly accurate information is difficult. In the banana comparison above, we may be able to get information on the carbon footprint emissions of the average container ship/plane that transported the banana to Amsterdam, but we likely won’t get the exact emissions of that exact plane or that exact container ship. At some point, we’ll almost always have to make assumptions and use less specific data to get to a carbon footprint number.
And when it comes to actionable data, the relative accuracy can often be more important than absolute accuracy. For example, I find it more useful to know that taking a plane represents an order of magnitude higher emissions than taking a car on the same trip; the relative difference is more important to me than the specific numbers as it shows me where I can take the most impactful reduction actions.
Meanwhile, having a carbon footprint number (with a baseline threshold for accuracy) for all the actions of an organisation creates a more useful big picture in a shorter time (and often at lower cost) than if one invested in getting very accurate numbers for one category, such as travel. Without this big picture, it’s hard to fully understand opportunities for reduction, and for this reason stakeholder’s won’t be satisfied with just a slice of the organisation’s footprint.
Additionally, if an organisation is concerned that it won’t be totally capturing it’s emissions if it occasionally compromises on accuracy, then I think at this point it’s okay to simply add a “buffer” to calculations, and purposely overestimate carbon footprints. This way, at the very least one can feel sure that emissions aren’t being underreported.
A practical approach for most organisations
I’d argue that for most organisations, starting with a focus on coverage over accuracy makes carbon accounting more approachable (which hopefully means more organisations do it!), as long as the resulting data is actionable. If you’re worried about not doing your fair share, an intermediate step is to purposely “overestimate” in areas you’re unsure about and then “over-offset” in areas where reduction is not currently possible.
Meanwhile, keep an eye on regulations and standards, as well as the development of new tools that make greater accuracy more attainable, and if you’re showing carbon footprint information to consumers, be extra careful and consider taking the time to get as bulletproof numbers as you can.