Tag Archives: radiocarbon anomaly

Neutralized carbon anomaly in the Gulf of California

By publication, , , , , , , , ,

Dr. Ryan Green just had a second manuscript accepted for publication, where we argue that the large-scale release of geologic carbon at the end of the last ice age is likely responsible for radiocarbon (14C) anomalies discovered in the Gulf of California region. Unlike any previous work, we argue that the carbon was released with and neutralized by alkalinity so as not to cause ocean acidification or atmospheric CO2 increase.

Green-et-al-2025-Paleo-GoCal-14C-accepted

Figure 4. Physical and geochemical constraints on geologic carbon addition. (a) Physical constraints showing simulated carbon release across a range of mixing rates (y-axis) and Marchitto Box sizes (x-axis, in multiples of GoC volume). Contours represent the total carbon required to simulate Δ14C anomalies, with gray lines indicating global radiocarbon budget limits (Green et al., 2024). Yellow and red circles denote slow and fast flushing end-member experiments, respectively, with black dashed lines showing their respective residence times of the Marchitto box. (b) Geochemical constraints based on PyCO2SYS (Humphreys et al., 2021) solver results and observations. Unlike Figure 3f, which covers the 20–10 ka interval, Figure 4b includes the full δ¹¹B-derived pH dataset extending back to 35 ka; no interpolation was applied. We apply a scaling relationship between 14C-free carbon addition and resulting Δ14C anomalies from the CYCLOPS carbon cycle model (ΔΔ14C = -0.31 * ΔDIC) to align PyCO2SYS-derived aragonite saturation state (Ω) contours with calculated ΔpH and ΔΔ14C from observed GoC data spanning 35 kyr to 11 kyr BP (yellow squares for benthic and red triangles for planktic). 1σ error bars are shown for the pH reconstruction derived from δ11B. Ω contours are calculated from a range of DIC and pH values, assuming a baseline DIC concentration of 2150 μmol kg⁻¹ and a pH of 8.07. Dashed black lines indicate ALK:DIC ratios for different hypothetical geologic carbon sources. Collectively, the δ¹¹B and Δ¹⁴C data are consistent with an ALK:DIC ratio in the range of 1.0–1.2, similar to the constant ratio of 1 used in our simulations and the mean ratio of ~1.1 estimated by Green et al. (2024). For all ratios in this range, CaCO₃ saturation (Ω) increases with carbon addition, consistent with the observed preservation of foraminiferal tests.

Neutralized carbon release in the past holds lessens for the future

By publication, ,

Ryan Green led a study investigating a the natural occurrence of geologic carbon release that is neutralized by alkalinity, so that it did not cause ocean acidification or atmospheric CO2 rise. The scale of the carbon pulse may have been twice the amount of all anthropogenic fossil fuel use combined. Studying this anomaly can give us clues about the effectiveness and environmental effects of purposeful Ocean Alkalinity Enhancement in an effort to neutralize anthropogenic CO2 and slow climate change.

Green-et-al-2024-GRL-deglacial-14C-anomaly