Introduction to special section on North Pacific Carbon Cycle Variability and Climate Change

Abstract

This article compares the major findings of eight synthesis papers resulting from a workshop to examine carbon cycle variability and climate change in the tropical and extratropical North Pacific Ocean. The workshop's intent was to encourage scientific exchange, synthesis activities, and the development of new ideas among scientists from different countries and backgrounds who do not regularly collaborate, but share a common interest in the Pacific. Six of the papers focus on air‐sea CO2 flux variability on timescales from years to decades. While the average North Pacific surface waters show increases in CO2 that are comparable to the increase in atmospheric CO2 over time, considerable temporal and spatial variations are observed. A recurring theme of these studies is that throughout most of the Pacific, interannual to decadal variations in CO2 fluxes are primarily controlled by variations in physical forcing with changes in the biological cycle being of secondary importance. The dominant mode of variability is confirmed to be associated with the El Niño–Southern Oscillation phenomenon, particularly in the tropical Pacific. Extratropical air‐sea CO2 flux variability is substantially smaller, primarily because dissolved inorganic carbon and temperature driven variations in the seawater pCO2 tend to compensate each other. Temporal variations in the wind fields are also important for assessing the variability in air‐sea CO2 fluxes. The two papers addressing carbon and oxygen cycle changes within the water column also found that variability in physical forcing can explain the magnitude and patterns of observed variability in apparent oxygen utilization and other tracers.