Table 1.
Atmospheric CO2 and surface seawater conditions at the two Great Barrier Reef stations averaged over the years 2009–2019.
| Total mean | Min | Max | Range | Winter mean | 5% | 95% | Summer mean | 5% | 95% | Decadal trend (units year−1 ± SE) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Atmospheric CO2 | |||||||||||
| Cape Ferguson Air CO2 (ppm) | 395.4 | 384.5 | 407.8 | 23.3 | 394.7 | 385.7 | 405.6 | 395.3 | 385.3 | 406.7 | 2.367 ± 0.0320 |
| Mauna Loa Air CO2 (ppm) | 398.4 | 384.4 | 414.7 | 30.2 | 398.6 | 387.5 | 410.7 | 397.3 | 387.9 | 407.2 | 2.389 ± 0.0147 |
| GBRWIS | |||||||||||
| Air CO2 (ppm) | 392.4 | 378.7 | 410.1 | 31.4 | 392.4 | 383.0 | 400.8 | 391.4 | 381.1 | 402.4 | 2.010 ± 0.0634 |
| fCO2 (µatm) | 369.8 | 314.4 | 456.5 | 142.1 | 339.4 | 321.2 | 364.5 | 405.9 | 380.7 | 435.9 | 1.792 ± 0.3612 |
| Temperature (°C) | 24.32 | 20.24 | 28.36 | 8.13 | 21.65 | 20.65 | 22.65 | 27.04 | 25.93 | 27.84 | 0.0429 ± 0.0127 |
| Salinity | 35.49 | 34.33 | 35.95 | 1.62 | 35.54 | 35.35 | 35.77 | 35.47 | 34.95 | 35.86 | 0.0387 ± 0.0051 |
| NRSYON | |||||||||||
| DIC (µmol kg−1 SW) | 1981 | 1914 | 2017 | 103 | 1991 | 1975 | 2005 | 1966 | 1922 | 1990 | 0.802 ± 0.239 |
| AT (µmol kg−1 SW) | 2300 | 2224 | 2338 | 113 | 2304 | 2273 | 2324 | 2293 | 2237 | 2319 | 0.0976 ± 0.256 |
| pHT* | 8.062 | 8.003 | 8.113 | 0.111 | 8.096 | 8.082 | 8.110 | 8.035 | 8.019 | 8.049 | -0.0012 ± 0.0004 |
| Ωar* | 3.586 | 3.230 | 3.921 | 0.691 | 3.455 | 3.253 | 3.589 | 3.735 | 3.604 | 3.842 | -0.0073 ± 0.0024 |
| fCO2 (µatm)* | 377.1 | 329.5 | 442.5 | 113.0 | 344.3 | 331.2 | 356.2 | 402.5 | 388.0 | 421.0 | 1.244 ± 0.377 |
| Revelle factor* | 9.27 | 8.90 | 9.71 | 0.80 | 9.42 | 9.24 | 9.67 | 9.09 | 8.99 | 9.21 | 0.011 ± 0.0033 |
| Temperature (°C) | 25.77 | 21.16 | 29.65 | 8.49 | 22.67 | 21.18 | 23.80 | 28.66 | 27.80 | 29.44 | 0.064 ± 0.0269 |
| Salinity | 35.29 | 34.02 | 36.05 | 2.02 | 35.34 | 34.83 | 35.60 | 35.14 | 34.15 | 35.62 | 0.0587 ± 0.0099 |
| DIN (µmol kg−1) | 0.111 | bdl | 1.137 | 1.137 | 0.123 | bdl | 0.443 | 0.106 | bdl | 0.373 | ns |
| Phosphate (µmol L−1) | 0.063 | bdl | 0.24 | 0.24 | 0.077 | 0.02 | 0.16 | 0.044 | bdl | 0.123 | ns |
| Si (µmol L−1) | 1.29 | 0.10 | 3.80 | 3.7 | 1.11 | 0.6 | 1.73 | 1.46 | 0.37 | 3.09 | ns |
Total means and ranges: GBRWIS: 3036 daily mean instrument-measured values, NRSYON: 109 monthly mean (depth-averaged) seawater samples. Atmospheric CO2 concentrations from Cape Ferguson (https://gaw.kishou.go.jp/search/station#CFA) and from Mauna Loa (sourced from www.esrl.noaa.gov/gmd/ccgg/trends/), and the means and percentiles for the two warmest (January and February) and coldest months (July and August). Also tabled are the estimated slopes (± standard errors) for the decadal trends derived from non-hierarchal GLM analyses of monthly averaged data (the seawater carbonate data corrected for variation with seasons, temperature, salinity and nutrients; Figs. 4, 6; Tables 2, 3; ns = not significant). *Variables calculated from DIC and AT for in situ temperature, pressure, nutrients and salinity, using CO2Sys61 with pK1 and pK2 dissociation constants of Dickson and Millero62 and KHSO4 dissociation constants of Dickson63, total borate of Uppstrom61 and the equilibrium constant for HF from Perez and Fraga62. pHT pH at total scale, Ωar aragonite saturation state, fCO2 fugacity of seawater CO2, bdl below detection limit. Measurements of DIC and AT used for CO2 system calculations were only available for NRSYON.