UC Santa Cruz Assistant Professor of Environmental Studies Scott Winton has been wading through thick, smelly muck in the tropics for almost a decade. He wouldn’t have it any other way. As a wetland ecologist and biogeochemist, he’s been hard at work investigating an important and mysterious topic: peatlands.
Peatlands are a special type of wetland with enormous potential to either help or hurt global efforts to address climate change. If we want peatlands on our side, we’ll have to protect them. But that’s difficult to do, since we still don’t yet know how many of them exist or where they are.
Winton’s latest research, published in the journal Environmental Research Letters provides the first data-driven map of both newly documented and predicted peatland areas across Colombia’s eastern lowlands. Institutions including ETH Zurich, Pontificia Universidad Javeriana, and Stanford University contributed to the research. Winton is lead author, and senior author Alison Hoyt is an Assistant Professor of Earth System Science at Stanford.
Winton and the team estimate that the region contains somewhere between 7,370 and 36,200 square kilometers of peatlands. Protecting these ecosystems could help Colombia reduce its carbon emissions as part of international climate change agreements.
Carbon emissions are the excessive amounts of carbon dioxide gas released into the atmosphere by human activities, especially the burning of fossil fuels like coal, oil, and natural gas. When excess carbon dioxide builds up in the atmosphere, it acts like a heat trapping blanket, warming our planet and resulting in climate change. To address the problem, we mainly need to reduce our use of fossil fuels. But it’s also important to conserve key ecosystems that naturally act as “carbon sinks,” trapping and storing some of our emissions underground.
That’s where peatlands come in. Peatlands are great at capturing carbon because their perpetually soggy soils deprive decomposer organisms of the oxygen they need to fully break down dead plants. Normally, plants absorb some carbon dioxide from the atmosphere and incorporate the carbon into their tissues, then when the plants die, decomposers digest them, releasing carbon dioxide back into the atmosphere. But in peatlands, the decomposition process grinds to a halt, so over time, a large amount of carbon accumulates and remains trapped in peat soils in the form of partially decomposed organic matter.
In Colombia, Winton’s team found that the average per-area carbon densities in peatlands are four to 10 times higher than in the Amazon rainforest. This finding tracks with what scientists know about the carbon sequestration abilities of peatlands in other parts of the world.
“On a global scale, peatlands cover only 3% of land surface but store more carbon than all of the world’s trees,” Winton explained. “We tend to focus on trees when we think about natural capacity to remove some of the excess carbon dioxide from our atmosphere, but peatlands punch way above their weight in terms of carbon storage.”
Essentially, peatlands are like unsung heroes that have been working behind the scenes to help buffer the impact of our fossil fuel emissions. But there’s a catch. Peatlands can only continue to store carbon if they remain consistently wet. When peatlands are drained for agriculture or other development, decomposer organisms in the soil get right back to work breaking down the partially decomposed organic matter in peat soils, releasing stored carbon into the atmosphere. Dried out peatlands can also catch fire, rapidly releasing their carbon stores.
Unfortunately, this scenario is currently playing out in some parts of the world.
“There has recently been mass drainage of peatlands for agriculture in Southeast Asia, resulting in soil compaction and subsidence and catastrophic wildfires that become a huge source of carbon to the atmosphere,” Winton said. “Indonesia, for example, is actually a huge outlier in terms of their emissions relative to GDP because of these types of land conversion. And once peatlands are destroyed, they can take 1,000 years to recover lost soil carbon, so it really demonstrates the importance of working proactively to protect these ecosystems.”
One of the major challenges in protecting peatlands is that they’re not always easily distinguishable from other types of wetlands based on their surface appearances. Documenting them requires careful investigation, but they remain understudied in many parts of the world. In Colombia, for example, five decades of civil war previously made many parts of the country inaccessible for ecological research. Peace agreements have now made research possible, but the country is also experiencing rapid environmental degradation, meaning there’s a good chance that peatlands are being destroyed before they can even be identified.
Finding Colombia’s peatlands and slowing the rate of their destruction could prevent the release of significant carbon stores, reducing the nation’s overall carbon emissions. With that goal in mind, Winton and a team of researchers set out in search of peat. Starting in regions identified by a global predictive map for wetlands, they talked with local people to get a sense for what plant communities might be associated with peatlands. Then they used satellite imagery to find promising areas to visit and investigate. It was a difficult, but ultimately rewarding process that spanned three years.
“We visited a lot of wetlands without finding any peat, and we kind of had to stumble around and struggle a bit before we figured out how to find what we were looking for,” Winton recalls. “One day we were swimming through chest-deep water in this swamp, and I remember diving down under the flood water to grab a handful of soil. That’s when we found our first peat, and we realized we were finally in the right place.”
Winton and his team ended up finding peat soils at 51 of the more than 100 wetland sites they visited. At each site where they found peat, they collected soil samples and detailed data on water conditions and plant communities. They identified two specific types of Colombian peatlands—palm swamps, and white-sand peatlands—both with forested and open variations. White-sand peatlands had not previously been documented in South America. Winton’s team described them as permanently wet areas forested by thin-stemmed and often stunted trees, growing in up to two meters of peat soil atop white sand.
The team’s new observations about the characteristics of Colombia’s peatlands allowed them to build an improved predictive model, showing where additional peatlands likely exist across Colombia’s lowlands. Researchers also analyzed the soil samples they collected in order to determine their carbon content. Taken together, these results allowed the team to estimate that Colombia’s peatlands may currently be sequestering an amount of carbon equivalent to 70 years worth of the country’s emissions from fossil fuels and industry.
Winton hopes that improved understanding of the value of these peatland resources and where they might be distributed could help local scientists and the Colombian government continue the work to identify and protect more of the country’s peatlands.
“There are many places across Colombia and around the world where we could still find large peatlands that we didn’t know existed that would totally upend current assumptions,” Winton said. “We really need more research across the tropics to groundtruth and identify the distribution of peatlands, so that we can prioritize their conservation globally with a more complete picture.”
Journal
Environmental Research Letters