Although increasing levels of atmospheric carbon dioxide have been well documented, the response of the ocean to these changes is less understood, particularly on regional space scales. Evidence is accumulating that there is substantial variability in the cycling of carbon and related biogeochemical elements over a wide range of timescales, including interannual and decadal timescales, which have been the focus of studies aimed at identifying a climate change signal. Most of these studies, however, have been limited in time, space, or number of parameters examined, preventing a full appreciation of the scale and magnitude of the changes. In June 2004, scientists gathered in Seattle, Washington, to synthesize individual studies of the North Pacific into a coherent picture of North Pacific carbon cycle changes, and to identify the requirements for detecting a long-term climate change signal. The workshop established many new international and interdisciplinary collaborations and helped develop plans for 14 synthesis manuscripts.