NOAA/WDS Paleoclimatology - Kona - Radiocarbon Data

We show that high-precision radiocarbon (Δ14C) measurements from annual bands of a Hawaiian surface coral decreased by 7‰ from AD 1893 to 1952. This decrease is coincident with the Suess Effect, which is mostly due to the dilution of natural levels of 14C by 14C-free fossil fuel CO2. This decrease is equal to that expected in surface waters of the subtropical gyres, and indicates that the surface waters of the North Pacific were in steady state with respect to long term mixing of CO2 during the past century. Correlation between Δ14C and North Pacific gyre sea surface temperatures indicates that vertical mixing local to Hawaii and the North Pacific gyre as a whole is the likely physical mechanism to result in variable Δ14C. Prior to 1920, this correlation starts to break down; this may be related to the non-correlation between biennial Δ14C values in corals from the southwest Pacific and El Niño events observed during this period as well.

本研究表明，夏威夷表层珊瑚年生长纹带的高精度放射性碳（Δ¹⁴C）测量值，在公元1893年至1952年间下降了7‰。该下降趋势与修斯效应（Suess Effect）高度吻合，该效应主要由不含¹⁴C的化石燃料二氧化碳稀释天然¹⁴C水平所致。该下降幅度与亚热带环流表层水域的理论预期值一致，表明过去一个世纪以来，北太平洋表层水域在二氧化碳长期混合过程中处于稳态。Δ¹⁴C与北太平洋环流海表温度之间的相关性显示，夏威夷局地垂直混合及北太平洋环流整体过程，是导致Δ¹⁴C产生变化的潜在物理机制。1920年之前，该相关性开始瓦解；这一现象可能也与同期西南太平洋珊瑚的两年期Δ¹⁴C值与观测到的厄尔尼诺事件之间不存在相关性有关。