Ocean Acidification Calculator Formula
Understand the math behind the ocean acidification calculator. Each variable explained with a worked example.
Formulas Used
Estimated Current pH
estimated_ph = ph_preindustrial - ph_droppH Decrease
ph_change = ph_dropH+ Ion Increase
h_ion_increase_pct = (pow(10, ph_drop) - 1) * 100Variables
| Variable | Description | Default |
|---|---|---|
co2_preindustrial | Pre-industrial CO2(ppm) | 280 |
co2_current | Current CO2(ppm) | 420 |
ph_preindustrial | Pre-industrial Ocean pH | 8.18 |
ph_drop | Derived value= 0.85 * log(co2_current / co2_preindustrial) / log(10) | calculated |
How It Works
Ocean Acidification and CO2
When CO2 dissolves in seawater it forms carbonic acid, lowering the pH. The ocean has absorbed about 30% of human-produced CO2.
Simplified Formula
Delta pH = 0.85 x log10(C / C0)
Where C and C0 are current and pre-industrial CO2 levels. The coefficient 0.85 approximates the buffering chemistry of seawater (the Revelle factor). Since pH is logarithmic, even a small drop represents a large increase in acidity.
Worked Example
CO2 has risen from 280 ppm to 420 ppm with pre-industrial pH of 8.18.
co2_preindustrial = 280co2_current = 420ph_preindustrial = 8.18
- 01CO2 ratio = 420 / 280 = 1.5
- 02log10(1.5) = 0.1761
- 03pH drop = 0.85 x 0.1761 = 0.1497
- 04Estimated pH = 8.18 - 0.150 = 8.030
- 05H+ increase = (10^0.150 - 1) x 100 = 41.3%
Ready to run the numbers?
Open Ocean Acidification Calculator