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Global Average Ocean pH by Year
- Pre-1750 (Baseline): 8.21
- 1800: 8.20
- 1850: 8.19
- 1870: 8.18
- 1890: 8.18
- 1900: 8.17
- 1910: 8.17
- 1920: 8.16
- 1930: 8.16
- 1940: 8.15
- 1950: 8.15
- 1960: 8.14
- 1970: 8.13
- 1980: 8.12
- 1990: 8.11
- 2000: 8.10
- 2010: 8.08
- 2020: 8.07
- 2023: 8.06
pH Decrease Per Decade (Global)
- 1800–1850: -0.002
- 1850–1900: -0.004
- 1900–1950: -0.004
- 1950–1980: -0.008
- 1980–2000: -0.010
- 2000–2020: -0.015
- 2020–2023: -0.020 (partial decade)
- Overall (1800–2023): -0.007
Regional pH Levels by Year
| Year | North Atlantic | Southern Ocean | Tropical Pacific | Arctic Ocean | Indian Ocean |
|---|
| 1900 | 8.16 | 8.15 | 8.18 | 8.14 | 8.17 |
| 1950 | 8.14 | 8.13 | 8.16 | 8.12 | 8.15 |
| 1980 | 8.12 | 8.11 | 8.14 | 8.10 | 8.13 |
| 2000 | 8.09 | 8.08 | 8.11 | 8.07 | 8.10 |
| 2010 | 8.07 | 8.06 | 8.09 | 8.05 | 8.08 |
| 2020 | 8.06 | 8.04 | 8.08 | 8.04 | 8.07 |
| 2023 | 8.05 | 8.03 | 8.07 | 8.03 | 8.06 |
Regional pH Decrease Per Decade (1980–2023)
- North Atlantic: -0.016
- Southern Ocean: -0.019
- Tropical Pacific: -0.016
- Arctic Ocean: -0.021
- Indian Ocean: -0.015
Cumulative pH Drop (1750–2023)
- Global: -0.15
- North Atlantic: -0.17
- Southern Ocean: -0.18
- Tropical Pacific: -0.14
- Arctic Ocean: -0.20
- Indian Ocean: -0.15
Acidity Increase (% Change in H⁺ Concentration)
- 1750–1900: +7%
- 1900–1950: +7%
- 1950–1980: +10%
- 1980–2000: +12%
- 2000–2023: +17%
- Total (1750–2023): +35%
Key Trends by Period
- 1800–1900: -0.003/decade (slow, pre-industrial rise)
- 1900–1950: -0.004/decade (early industrial)
- 1950–1980: -0.008/decade (post-war CO2 surge)
- 1980–2023: -0.017/decade (rapid acceleration)
CO2 Absorption Context
- 1900: 0.5 GtC/year (gigatons carbon)
- 1950: 1.5 GtC/year
- 1980: 2.5 GtC/year
- 2000: 3.0 GtC/year
- 2020: 3.5 GtC/year
- Correlation: Higher CO2 uptake = faster pH drop
Extreme Data Points
- Fastest Decline: Arctic Ocean, -0.025 (2010–2020)
- Slowest Decline: Tropical Pacific, -0.002 (1900–1950)
- 2023 Low: Southern Ocean, 8.03
