Tropical peatlands and their contribution to the global carbon cycle and climate change

Abstract

Peatlands are carbon‐rich ecosystems that cover 185–423 million hectares (Mha) of the earth's surface. The majority of the world's peatlands are in temperate and boreal zones, whereas tropical ones cover only a total area of 90–170 Mha. However, there are still considerable uncertainties in C stock estimates as well as a lack of information about depth, bulk density and carbon accumulation rates. The incomplete data are notable especially in tropical peatlands located in South America, which are estimated to have the largest area of peatlands in the tropical zone. This paper displays the current state of knowledge surrounding tropical peatlands and their biophysical characteristics, distribution and carbon stock, role in the global climate, the impacts of direct human disturbances on carbon accumulation rates and greenhouse gas (GHG) emissions. Based on the new peat extension and depth data, we estimate that tropical peatlands store 152–288 Gt C, or about half of the global peatland emitted carbon. We discuss the knowledge gaps in research on distribution, depth, C stock and fluxes in these ecosystems which play an important role in the global carbon cycle and risk releasing large quantities of GHGs into the atmosphere (CO2 and CH4) when subjected to anthropogenic interferences (e.g., drainage and deforestation). Recent studies show that although climate change has an impact on the carbon fluxes of these ecosystems, the direct anthropogenic disturbance may play a greater role. The future of these systems as carbon sinks will depend on advancing current scientific knowledge and incorporating local understanding to support policies geared toward managing and conserving peatlands in vulnerable regions, such as the Amazon where recent records show increased forest fires and deforestation.

Committed and projected future changes in global peatlands – continued transient model simulations since the Last Glacial Maximum

“…Output data were used for monthly precipitation, surface temperature, and cloud cover from the "r1i1p1f1" variant of the respective historical simulations and future scenarios SSP1-2.6, SSP2-4.5, and SSP5-8.5 mated to store 270 to 604 gigatons of carbon (GtC), using various methods and area estimates (see Yu, 2012, andYu et al, 2014, for a review). For tropical peatlands, estimates of organic carbon storage range from 44 to 92 GtC in earlier estimates (Yu et al, 2010;Page et al, 2011) and increase as a result of larger assumed areas in recent estimates from 70 to 288 GtC (Dargie et al, 2017;Ribeiro et al, 2021). In the year 1975, peatlands simulated by the LPX-Bern have accumulated about 441 GtC of soil organic carbon globally.…”

Global peatlands under future climate – seamless model projections from the Last Glacial Maximum

“…Northern peatlands have been estimated to store 270 to 604 gigatons of carbon (GtC), using various methods and area estimates (see Yu (2012) and Yu et al (2014) for a review). For tropical peatlands estimates of organic carbon storage range from 44 to 92 GtC in earlier estimates (Yu et al, 2010;Page et al, 2011) and increase as a result of larger assumed areas in recent estimates from 70 to 288 GtC (Dargie et al, 2017;Ribeiro et al, 2021). At the year 1975, peatlands simulated by the 5 LPX-Bern have accumulated about 441 GtC of soil organic carbon globally.…”

Exploring Dissolved Organic Carbon Variations in a High Elevation Tropical Peatland Ecosystem: Cerro de la Muerte, Costa Rica

“…Peatlands are a type of wetlands which are defined as having saturated soils, dense vegetation, anoxic conditions, and large deposits of partially decomposed organic plant material or peat (i.e., soil organic matter 30-50% in a 20-40 cm profile) (Yu, 2011;Page and Baird, 2016;Bourgeau-Chavez et al, 2018;Villa et al, 2019;Ribeiro et al, 2021). Peat accumulates as a result of the long-term imbalance between carbon production and decomposition (Hapsari et al, 2017;Bourgeau-Chavez et al, 2018).…”

“…Tropical peatlands are distributed mainly in the river deltas and coastal plains, although mountainous areas also contain many small and fragmented peatlands (Hribljan et al, 2016;Hapsari et al, 2017;Lourençato et al, 2017;Silva et al, 2019). Mountainous peatlands offer a broad spectrum of ecosystem services, such as regulating stream discharge and lowland flooding, sediment and nutrient retention, carbon storage, and are home of a large number of endemic species (Kimmel and Mander, 2010;Ribeiro et al, 2021). Artificial peatland drainage may result in the net loss of the C storage function and in a large release of greenhouse gases to the atmosphere (e.g., CO, CO 2 , and CH 4 ; Page and Baird, 2016).…”