Major natural carbon sink may soon become carbon source – News

WEST LAFAYETTE, Ind. – Until humans can find a way of geo-engineering us out of the climate disaster we've created, we have to rely on natural carbon sinks, such as oceans and forests, to suck carbon dioxide from the atmosphere. Ecosystems are deteriorating as a result of climate change. Once destroyed, they risk not only absorbing carbon from the atmosphere, but also emitting it.

Ecosystems that harbor a type of carbon-rich soil called peat are the most effective natural carbon sinks on the planet. When they are not disturbed, they store more carbon dioxide than any other type of vegetation on Earth. But when they are drained and deforested, they can release nearly 6% of global carbon dioxide emissions each year. Climatologists worry that many carbon-absorbing peatlands will soon do the opposite.

"Global peatlands cover only about 3% of the total area of ​​the globe, but contain about 30% of soil organic carbon," said Qianlai Zhuang, professor of Earth, Atmospheric and Planetary Sciences. Purdue University. "Peatlands act as a" terrestrial ocean "because of their carbon sequestration, but will this large amount of peat carbon be released in a warmer climate, causing additional warming?"

In collaboration with Sirui Wang, Ph.D. candidate for Purdue, Zhuang has turned to the peat bogs of the Peruvian Amazon to try to answer this question.

According to a land-based model dating back 12,000 years to 2100 AD, this relatively small basin could lose up to 500 million tons of carbon by the end of the century. This is about 5% of the global annual carbon emissions of fossil fuels, or 10% of US emissions, released into the atmosphere.

According to most estimates, South America will become both warmer and wetter by the end of the century. Zhuang's findings, published Monday in the Proceedings of the National Academy of Sciences, show that higher temperatures lead to increased loss of peat carbon, while increased precipitation slightly improves carbon accumulation of peat. long term. Together, this will likely increase peatland carbon losses in the atmosphere.

The peatlands of northwestern Peru remain almost intact, but this is not the case in most places where peat stocks are important and are cleared to make way for agriculture. Peatlands in parts of the world, including Canada, Siberia and Southeast Asia, have already become important sources of carbon. The same fate could soon arrive for the Peruvian peat bogs.

"If the area we examined could represent the entire Amazon or tropical peatlands, the loss of peat carbon in the atmosphere under future climate scenarios should be of great concern to our society" Zhuang said. "The intensification of agriculture and the increasing disruption of land use, such as forest fires, threaten the persistence of peat carbon stocks. These peatland ecosystems can become carbon sources rather than sinks unless the necessary steps are taken. "

Researchers from Arizona State University, Carnegie Institution for Science, and Florida International University contributed to this work. The study was funded by the National Science Foundation and the Department of Energy.

Writer: Kayla Zacharias, 765-494-9318, [email protected]

Source: Qianlai Zhuang, [email protected]

Note to journalists: For a copy of the document, please contact Kayla Zacharias, Purdue News Service, at [email protected].

ABSTRACT

Amazon peatlands store a large amount of organic carbon in the soil and its fate in a future changing climate is unknown. Here we use a biogeochemistry model based on peatland processes to quantify the carbon accumulation of peat and non-peat ecosystems in the Pastaza-Marañon (Peruvian Amazon) foreland basin from 12,000 years to the present day up to the present day. At 2100 AD. Model simulations indicate that warming accelerates the loss of SOC by peat while increasing precipitation accelerates its accumulation at millennial scales. Uncertain parameters and spatial variation in climate are important sources of uncertainty for modeling carbon accumulation in peat. During the 21st century, in warmer and probably wetter conditions, the rate of SOC accumulation in PMFB has slowed to 7.9 (4.3 ~ 12.2) g C m% & yr%). current rate of 16.1 (9.1 ~ 23.7) g C m% &%) and the region can become a source of carbon in the atmosphere at -53.3 (-66.8 ~ -41.2 ) (negative indicates the source), depending on the level of warming. Peatland ecosystems are more vulnerable than ecosystems other than peatlands, as indicated by the ratio of carbon density changes in their soils (ranging from 3.9 to 5.8). This is mainly due to the higher carbon stocks of peatlands and the more dramatic reactions of their aerobic and anaerobic decomposition to non-peatland ecosystems under future climatic conditions. The peat and non-peat soils of PMFB can lose up to 0.4 (0.32 ~ 0.52) Pg C by 2100 AD, the largest loss from palm swamps. Amazon's carbon-rich peatlands are likely to move from the current carbon sink to the 21st century.