The California Current System is a coastal upwelling biome, as found along the eastern margins of all major ocean basins. These are among the most productive  ecosystems in the world ocean. The California Current Ecosystem LTER (32.9°, -120.3°) is investigating nonlinear transitions in the California Current coastal pelagic ecosystem, with particular attention to long-term forcing by a secular warming trend, the Pacific Decadal Oscillation, and El Niño in altering the structure and dynamics of the pelagic ecosystem. The California Current sustains active fisheries for a variety of finfish and marine invertebrates, modulates weather patterns and the hydrologic cycle of much of the western United States, and plays a vital role in the economy of myriad coastal communities.