Look for a common driver before linking ocean series

Strong correlation and a plausible lead can arise when two ocean records share a driver rather than directly influence one another. This methods note combines Earth-system causal-inference research with studies of nonlinear ecological dynamics and autocorrelated fish-environment data. An invented two-regime calculation produces a correlation of approximately 0.94 despite zero within-regime association and no constructed direct effect. The analysis then examines lagged common forcing, sampling and smoothing, seasonal transformations, adjustment choices, and the assumptions behind advanced causal methods. It attributes no actual ocean event and does not claim that conditioning alone establishes causation. Its practical outcome is a sequence of rival physical explanations and discriminating observations, allowing unresolved associations to guide a better next measurement instead of an overstated causal story.