Journal of Oceanography, Vol. 60 (No. 1), pp. 5-15, 2004
Christopher L. Sabine1*, Richard A. Feely1, Yutaka W. Watanabe2 and Marilyn Lamb1
1NOAA/PMEL, 7600 Sand Point Way NE, Seattle, WA 98115, U.S.A.
2Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
(Received 10 September 2003; in revised form 29 November 2003; accepted 30 November 2003)
Abstract: The recent changes in the North Pacific uptake rate of carbon have been estimated using a number of different techniques over the past decade. Recently, there has been a marked increase in the number of estimates being submitted for publication. Most of these estimates can be grouped into one of five basic techniques: carbon time-series, non-carbon tracers, carbon tracers, empirical relationships, and inverse calculations. Examples of each of these techniques as they have been applied in the North Pacific are given and the estimates summarized. The results are divided into three categories: integrated water column uptake rate estimates, mixed layer increases, and surface pCO2 increases. Most of the published values fall under the water column integrated uptake rate category. All of the estimates varied by region and depth range of integration, but generally showed consistent patterns of increased uptake from the tropics to the subtropics. The most disagreement between the methods was in the sub-arctic Pacific. Column integrated uptake rates ranged from 0.25 to 1.3 mol m-2yr-1. The mixed layer uptake estimates were much more consistent, with values of 1.0-1.3 mmol kg-1yr-1 based on direct observations and multiple linear regression approaches. Surface pCO2 changes showed the most obvious regional variability (0.5-2.5 matm yr-1) reflecting the sensitivity of these measurements to differences in the physical and biological forcing. The different techniques used to evaluate the changes in North Pacific carbon distributions do not completely agree on the exact magnitude or spatial and temporal patterns of carbon uptake rate. Additional research is necessary to resolve these issues and better constrain the role of the North Pacific in the global carbon cycle.