Completeness refers to an accounting of all applicable sources and sinks. In
the context of a Kyoto Protocol accounting system, the sources and sinks that
are "applicable" would be defined by the provisions of the Protocol.
Accuracy refers to the general validity of the reported numbers from an accounting
system. Accurate estimates are unbiased in that they do not systematically under-
or overstate the true number. A related issue is precision. Precise estimates
have small standard errors. Accuracy and precision can be independent. A system
can be accurate (unbiased) but produce estimates of limited precision. On the
other hand, extremely precise estimates can be biased if the system is not well
The accounting system should enable a third party to verify the reported numbers.
Verifiability requires that the accounting system is built on proper data collection,
measurement, and reporting procedures. For instance, claims that relevant LULUCF
activities sequestered a given quantity of carbon over a certain period of time
should be based on substantiated data, models, and methods. The location and
extent of the land on which the claimed carbon sequestration took place should
also be clearly identified, preferably using a consistent geographic information
system that would facilitate identification of possible double-counting and
the overlay of information used for verification (e.g., remote-sensing data).
In short, claims should be able to withstand reasonable scrutiny.
An accounting system is not free. Systems that are more accurate, precise,
and verifiable may be more expensive to develop and operate. An efficient accounting
system operates at the point where the marginal costs of increased accuracy,
precision, and verifiability just equal the marginal benefits of achieving the
improvements. When resources are not available to obtain an efficient system,
the objective should be to obtain the most effective system given the available