One possible uncertainty in CMIP5 projections of low‐oxygen water volume in the Eastern Tropical Pacific. Issue 5 (13th May 2017)

• Record Type: Journal Article
• Authors: Shigemitsu, M.; Yamamoto, A.; Oka, A.; Yamanaka, Y.
• Is Part Of: Global biogeochemical cycles. Volume 31:Issue 5(2017:May)
• Page Start: 804
• Page End: 820
• Publication Date: 2017-05-13
• Subjects: oxygen -- future projection -- Equatorial Undercurrent -- CMIP5 -- biogeochemical model; Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1002/2016GB005447
• Languages: English
• ISSNs: 0886-6236

Abstract

Abstract: Using the results from nine Earth system models submitted to the Coupled Model Intercomparison Project Phase 5 (CMIP5), we identify the Eastern Tropical Pacific (ETP) as the region with the greatest uncertainty of future changes in oxygen‐deficient (<30 μ M ) water volumes since different models variously project both positive and negative changes in the oxygen‐deficient volume and export flux there. We investigate the factors controlling future changes in oxygen‐deficient volume in the ETP with global warming using a single off‐line biogeochemical model. Oxygen budget analysis clarifies that the Equatorial Undercurrent (EUC) is the key mechanism controlling future variations in the oxygen‐deficient volume in the ETP in our model. From the outputs of all of the CMIP5 models and our model, we identify a significant negative relationship between changes in the EUC volume transport and the oxygen‐deficient water volume from the present to the end of the 21st century, which indicates that the response of the EUC to global warming leads to one possible uncertainty in future projections of oxygen‐deficient volume in the ETP. Key Points: Regions of uncertainty in future projections of oxygen‐deficient water ocean volume are spatiotemporally identified Oxygen budget analysis is conducted in the Eastern Tropical Pacific using a biogeochemical model Future changes in the Equatorial Undercurrent volume transport lead to uncertainty in the projection of oxygen‐deficient volumes