In forming judgements about condition of any parameter, a “benchmark” (a point of reference for the condition) is needed. Ideally, the benchmark is the condition of the parameter prior to the time when human impacts started to occur. In practice, benchmarks are mainly chosen for their convenience and to include times when data are available.
The reason is because “ideal” benchmarks will vary greatly from one part of the world to another; it may be the time of European settlement in one place, or before the Roman Empire in another. Humans may have had significant impacts on some ecosystems prior to the “benchmark” time and impacts may have accumulated gradually over a long time period afterwards. Where it is difficult to identify an appropriate benchmark we recommend that the year 1900 be used. This date (1900) has the advantage that most scientific observations of the marine environment are subsequent to it.
The use of a benchmark should not be confused with an objective for management; it is not the purpose of the SOME-EE process to make recommendations on national marine environmental goals or polices. The establishment of a benchmark is only for the purpose of quantifying environmental change relative to the present time.