Mangroves are substantial coastal carbon stores, with soils holding most of the measured global stock. Published estimates show wide variation by geography and depth: global benchmarks range from hundreds to more than 1,000 Mg C per hectare, while local studies reveal how strongly ecosystem type shapes the result.
Contents
- Global mangrove carbon storage benchmarks
- Where mangrove carbon is stored
- Country-level carbon stocks
- Lamu, Kenya: ecosystem-scale storage
- Celestún, Mexico: depth and ecological type
- Loss, sequestration, and projections
Global mangrove carbon storage benchmarks
The study Global carbon stocks and potential emissions due to mangrove deforestation from 2000 to 2012 estimated that global mangroves stored 4.19 Pg of carbon in 2012. Of that total, 2.96 Pg was in soil and 1.23 Pg was in living biomass. The same study reported a 2% decline in global mangrove carbon stock between 2000 and 2012. Its maximum potential carbon-dioxide emissions associated with that loss were 316,996,250 tonnes of CO2. These figures describe the 2000–2012 assessment period, rather than a current measurement. (Nature Climate Change)
A separate mapping study, Mapping accumulated carbon storage of global mangroves from 2000 to 2020 at a 1 km resolution, estimated the global mangrove carbon stock at 8,768 Mt in 2000, with a modeled range of 8,050–9,486 Mt. Across its 2000–2020 dataset, the modeled global average mangrove carbon stock was 1,297 Mg per hectare. (Scientific Data)
The IPCC synthesis Chapter 3: Oceans and Coastal Ecosystems and their Services reports mangrove carbon stocks of 856 ± 64.2 Mg C per hectare for a sampling period of 2007–2017. It also gives a broad stock range of 79–2,208 Mg C per hectare. The spread is important: a global average is a benchmark, not a reliable substitute for a site measurement. (IPCC)
Where mangrove carbon is stored
The distribution among carbon pools helps explain why mangrove conservation is not only about retaining standing trees. The study Total Ecosystem Carbon Stocks of Mangroves in Lamu, Kenya; and Their Potential Contributions to the Climate Change Agenda in the Country cites a global estimate reported in 2021 that assigns 70.65% of mangrove carbon storage to soils, 19.57% to above-ground biomass, and 9.78% to below-ground biomass. (Frontiers in Forests and Global Change)
The IPCC synthesis gives a mean mangrove carbon-burial rate of 194 ± 30 g C per square metre per year for its 2007–2017 sampling period. The reported rate range was 6.2–1,722 g C per square metre per year, showing how variable burial can be across sites. A global estimate reported in 2022 put mangrove carbon burial at 41 Tg C per year, paired with a global mangrove area of 13.7 million hectares. (IPCC)
| Carbon-storage measure | Reported value | Period or basis |
|---|---|---|
| Global stock | 4.19 Pg C | 2012 |
| Soil share of global stock | 70.65% | Global estimate reported 2021 |
| IPCC mean stock | 856 ± 64.2 Mg C/ha | Sampling period 2007–2017 |
| IPCC mean burial rate | 194 ± 30 g C/m²/year | Sampling period 2007–2017 |
| Global burial | 41 Tg C/year | Estimate reported 2022 |
Country-level carbon stocks
The study Future Mangrove Carbon Storage Under Climate Change and Deforestation provides current modeled country estimates based on 2012 coverage. Indonesia had the largest listed stock at 1,099.24 ± 103.77 Tg C. Australia was estimated at 406.78 ± 56.65 Tg C, followed by the Philippines at 325.13 ± 30.13 Tg C and Brazil at 265.59 ± 32.94 Tg C. These are modeled estimates tied to the stated coverage basis, not direct measurements taken across every mangrove area in the countries.
The same study estimated 174.14 ± 26.21 Tg C for Mexico and 170.47 ± 16.66 Tg C for Malaysia. Myanmar was estimated at 154.59 ± 33.68 Tg C, Papua New Guinea at 143.14 ± 14.80 Tg C, Cuba at 135.15 ± 13.29 Tg C, and Nigeria at 96.81 ± 10.66 Tg C. (Frontiers in Marine Science)
| Country | Modeled mangrove carbon stock |
|---|---|
| Indonesia | 1,099.24 ± 103.77 Tg C |
| Australia | 406.78 ± 56.65 Tg C |
| Philippines | 325.13 ± 30.13 Tg C |
| Brazil | 265.59 ± 32.94 Tg C |
| Mexico | 174.14 ± 26.21 Tg C |
| Malaysia | 170.47 ± 16.66 Tg C |
| Myanmar | 154.59 ± 33.68 Tg C |
| Papua New Guinea | 143.14 ± 14.80 Tg C |
| Cuba | 135.15 ± 13.29 Tg C |
| Nigeria | 96.81 ± 10.66 Tg C |
Lamu, Kenya: ecosystem-scale storage
The 2021 Lamu assessment estimated 20 million Mg C in total ecosystem carbon across the area. It reported a combined mangrove area of 35,678 hectares and a total carbon stock of 19,987,529.16 Mg C. The combined ecosystem carbon density was 560.22 ± 64.26 Mg C per hectare.
The pool-level results were 393.66 ± 79.35 Mg C per hectare for soil organic carbon, 127.85 ± 40.52 Mg C per hectare for above-ground biomass, and 38.72 ± 11.84 Mg C per hectare for below-ground biomass. Total biomass carbon density was 166.56 ± 52.35 Mg C per hectare. (Frontiers in Forests and Global Change)
Lamu also showed geographic variation within the assessment. Southern swamps had total ecosystem carbon density of 670.73 ± 98.75 Mg C per hectare, while northern swamps had 561.31 ± 124.40 Mg C per hectare. Northern central swamps measured 530.36 ± 132.63 Mg C per hectare, Pate Island swamps 525.36 ± 100.61 Mg C per hectare, and Mongoni and Dodori Creek swamps 513.36 ± 92.09 Mg C per hectare.
Soil values varied as well. Southern swamps had soil organic carbon density of 521 ± 108.2 Mg C per hectare, compared with 306.8 ± 147.5 Mg C per hectare in northern swamps. Those differences show why local conservation planning benefits from ecosystem-specific carbon inventories.
Celestún, Mexico: depth and ecological type
The Celestún field study, reported in 2023, measured soil carbon by ecological type and depth. In fringe mangroves, soil carbon was 49.30 ± 14.80 Mg C per hectare at 0–15 cm, 90.01 ± 24.36 Mg C per hectare at 15–30 cm, 80.72 ± 38.17 Mg C per hectare at 30–50 cm, and 180.80 ± 78.46 Mg C per hectare at 50–100 cm.
In basin mangroves, the corresponding measurements were 46.59 ± 10.78 Mg C per hectare at 0–15 cm, 45.76 ± 12.71 Mg C per hectare at 15–30 cm, 59.02 ± 21.50 Mg C per hectare at 30–50 cm, and 152.06 ± 58.15 Mg C per hectare at 50–100 cm.
The Petén measurements reported 300.62 ± 73.66 Mg C per hectare at 50–100 cm and 449.25 ± 178.35 Mg C per hectare below 100 cm. The estimated Celestún ecosystem carbon stock was 9.7 Tg C, with a 95% confidence interval of 8.6–10.9 Tg C. (Frontiers in Forests and Global Change)
Loss, sequestration, and projections
The modeled current mean total mangrove carbon stock in Future Mangrove Carbon Storage Under Climate Change and Deforestation was 472.7 ± 56.4 Mg C per hectare. Its modeled median mangrove soil sequestration rate was 172.5 g C per square metre per year, with a 95% confidence interval of 101.4–321.7. Indonesia accounted for 23.72 ± 0.09% of modeled global annual mangrove soil sequestration. These values are modeled estimates based on 2012 coverage and, for the sequestration estimate, 2012 climate data. (Frontiers in Marine Science)
Estimated mangrove-deforestation emissions declined across the historical periods reported by that study: 193.2 ± 44.4 Tg CO2e per year in the 1980s, 149.6 ± 33.3 Tg CO2e per year in the 1990s, and 8.8 ± 2.0 Tg CO2e per year between 2000 and 2010. The study projected global mangrove-deforestation emissions of 678.50 ± 151.32 Tg CO2e from 2012 to 2095. That final figure is a forecast for the stated period, not a measured historical total.
For an SSP245 comparison, the study modeled current global tree carbon stocks at 1,246.9 ± 427.1 Tg C and global soil carbon stocks to 1 m depth at 3,296.1 ± 114.8 Tg C. The separate tree and soil figures reinforce the importance of below-ground storage when assessing mangrove carbon risk.