Table 1.
Severity of impacts in different models
| Scenario | Minimum surface Ωcalcite* | |||||
| Alkalinity removal from surface ocean, Pmol | Carbon addition to atm, Pg | JModel (Cretaceous) | LOSCAR† (Paleocene) | JModel (preindustrial) | Duration of peak impact‡ | |
| Gypsum vaporization (SO4) | 120 | — | 0.0 | 0.0 | 0.0 | <5 y |
| NOx generation | 5 | — | 6.1 | 3.6 | 3.8 | <5 y |
| Carbon dioxide (CO2) | — | 6,500 | 2.2 | 1.4 | 0.7 | Thousands of years |
| Stirring | — | — | 5.4 | — | 3.8 | <5 y |
| All | 125 | 6,500 | 0.0 | 0.0 | 0.0 | <5 y |
| All except SO4 | 5 | 6,500 | 2.1 | 1.0 | 0.6 | <5 y |
| Rapid addition of SO4 | 120 | — | 0.0 | 0.0 | — | <1 y |
| Rapid addition of NOx | 5 | — | 3.4 | — | — | <1 y |
| Rapid addition of CO2 | — | 6,500 | 2.2 | — | — | — |
*
For each scenario the lowest minimum Ωcalcite is taken from the run in which the largest amount of substance (for instance 60 × 1015 mol, for SO4) is added over an e-folding time of 6 mo, except for rapid additions where the e-folding time was 10 h. Initial (preaddition) values of surface Ωcalcite were 7.5 (JModel Cretaceous), 4.9 (LOSCAR Paleocene, ref. 52), and 4.9 (JModel preindustrial).
†
Average across all ocean basins. A run with increased stirring was not implemented for this model.
‡
Time for which Ωcalcite was at least 80% of the maximum distance from the initial value.