Fig. 3: Occurrences of ocean acidification extreme events.
From: Modulation of ocean acidification by decadal climate variability in the Gulf of Alaska
Plots showing the relative occurrence of a saturation state for aragonite (Ωarag), b pH, and c pCO2 (μatm) for an area in the middle of the subpolar gyre (55 °N to 57 °N, 147 °W to 150 °W) from 1980 through 2013. The blue line shows the Northern Gulf of Alaska Oscillation (NGAO) index at a monthly frequency, smoothed with a 12 month running mean to highlight the effect of sub-decadal pulse disturbances on top of the decadal press from rising atmospheric CO2. The dashed blue line separates the positive from the negative NGAO phases. The solid black line shows the 10th percentile of the distribution of Ωarag and pH, and the 90th percentile of the distribution of pCO2 after applying a 10-year low pass filter to illustrate when an arbitrary threshold would be crossed as a result of the long-term press of ocean acidification. The pink dots show the 10th percentile of monthly Ωarag and pH, and the 90th percentile of monthly pCO2 model output to indicate when an arbitrary threshold would be crossed as a consequence of the NGAO (or pulses) in addition to seasonal periods of ocean acidification stress. The dashed red line is an arbitrary threshold to mark extreme events, when the sub-decadal pulse disturbances push the system across these thresholds (Ωarag = 1.3; pH = 8.0; pCO2 = 450 μatm).
