In 1999 the California Current changed. The ocean cooled, became somewhat less thermally stratified, and several characteristic species of zooplankton either decreased or increased in biomass. Many of these changes have persisted since that time (Figure 1). These ecosystem changes follow earlier shifts that occurred in 1976–77. Imagine the potential for misunderstanding the Northeast Pacific in the absence of such long-term observations. Any single year or limited group of years could yield a spurious picture of a dynamic ecosystem. Policy decisions and management guidelines would fail because they failed to take account of the underlying long-term variability.

Ohman, M.D., and E.L. Venrick. 2003. CalCOFI in a changing ocean. Oceanography 16(3):76–85, https://doi.org/10.5670/oceanog.2003.34.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.