way to learn about the ecosystem is to study forces on it and observe the
responses. One of the chief forcing agents on the world's oceans
is weather. The Pacific Decadal Oscillation (PDO) is a climate feature
that captures much of the variability in meteorological forcing over the
Bering Sea and North Pacific Ocean. For example, the progressional
change in ocean temperature is well described by the PDO. Phases
seem to last a few tens of years, then change. Physical and biological
features also track the PDO.