Global warming induced inconsistencies in ocean acidification rates based on pH25oC and pHinsitu
Ocean acidification is an unavoidable consequence of increased anthropogenic CO2,and even a small change in seawater pH may cause large impacts on oceanic ecosystems.In this study,acidification rates from two open access time-series studies are compared with that of six published time series studies.Conventionally,surface ocean is considered as under or close to air-sea CO2 equilibrium.As a result,pH is expected to have an average decreasing rate of -0.0017 yr-1 within the past 2-3 decades.The results show,however,although atmospheric CO2 rises at similar rates globally,reported rates of changes in pH either measured at in situ temperature (pHinsitu) or at 25 oC (pH25) vary from +0.00018~-0.0021 yr-1 to -0.00071~-0.0032 yr-1,respectively.Instead of acidifying,in the South East Asia Time-Series (SEATS) study of the world’s largest marginal sea — the South China Sea — the pHinsitu changing rate is actually slightly increasing.Conversely,the pH25 at SEATS decreases at a rate 75% faster than expected under the observed atmospheric CO2 increment.Such inconsistencies are consistent with the thermodynamics that pHinsitu and pH25 time-series are incomparable as they change in anti-phase when seawater temperature changes.At the SEATS station,the seasonal change in pHinsitu when temperature changes is 6-times of that expected under the air-sea CO2 equilibrium.This is due to a positive feedback of warming on ocean acidification which implies that aquatic ecosystems suffering from ocean acidification could be affected earlier than expected when warming is considered along with increasing atmospheric CO2.
ocean acidification warming pH carbon dioxide
Hon-Kit Lui Chen-Tung Arthur Chen Yu-Chang Chang
Institute of Marine Geology and Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
国际会议
The 17th Pacific -Asian Marginal Seas Meeting(第十七届太平洋与亚洲边缘海国际会议)
杭州
英文
886-891
2013-04-23（万方平台首次上网日期，不代表论文的发表时间）