An Overlooked Plant Group Helps Regulate Earth's Carbon Cycle — a Higher-CO2 World Could Change That

New invited review in Trends in Plant Science synthesizes decades of research on mosses' outsized role in carbon storage, and reveals how these ancient plants respond to rising atmospheric CO2

ST. LOUIS, MO (August 6, 2026) — A new review from the Donald Danforth Plant Science Center examines how mosses, small and often overlooked among land plants, exert an outsized influence on Earth's carbon cycle, and how they may respond as atmospheric CO2 continues to climb.

The review, published this week in Trends in Plant Science, was authored by Boominathan Mohanasundaram, a research scientist at the Danforth Center (currently at the Indian Institute of Science Education and Research), and Sona Pandey, PhD, a principal investigator at the Danforth Center and fellow of the American Society of Plant Biologists. It draws together research spanning biogeochemistry, paleobotany, and molecular biology to explain why mosses, despite lacking the specialized water-management and carbon-concentrating systems found in most other plants, dominate plant life across vast stretches of the planet.

Mosses are frequently the primary photosynthetic organisms in the Arctic tundra, Antarctic rock surfaces, and northern peatlands, ecosystems that cover a small share of Earth's land surface but store an outsized portion of its soil carbon. Peatlands alone hold roughly a third of all soil carbon worldwide, more than twice the amount held in all the world's forest biomass combined. Sphagnum—the peat moss genus that engineers these ecosystems—and the moss mats that insulate Arctic permafrost, are both central to keeping that stored carbon out of the atmosphere.

The review also details Dr. Pandey's own research on how mosses respond to elevated CO2, using Physcomitrium patens, a widely used model moss. Her lab found that under elevated CO2, this moss can accumulate up to three times more biomass than under current atmospheric conditions, a substantially larger gain than has been documented in most vascular plants. The moss also grew longer rhizoids, the root-like structures mosses use to anchor themselves and draw in nutrients, and progressed through its life cycle faster, changes tied to shifts in sugar signaling and nitrogen availability. They are extending this work to sphagnum, to determine how elevated CO2, combined with high temperature will affect its growth and degradation, aimed toward understanding of the stability of peatland ecosystems.

“Mosses are usually dismissed as primitive or unimportant because of their size and simple body plan,” said Dr. Pandey. “But they've persisted through atmospheric CO2 levels ranging from roughly 100 to 2,500 parts per million over hundreds of millions of years, and they're still actively shaping how carbon moves through the planet's systems today. If we want to understand how ecosystems will respond to climate change, we can't leave mosses out of that picture.”

“Sustainability starts with understanding the systems we depend on, and this research is a reminder that some of the most important ones are also the least visible,” said Danforth Center President Giles Oldroyd, PhD. “Mosses have been quietly regulating carbon for hundreds of millions of years. Learning how they'll respond as the climate changes gives us information we need to protect the peatlands and permafrost that keep enormous amounts of carbon out of the atmosphere. This is vitally important plant science as we work toward a more sustainable future.”

The Danforth Center's mission is to improve the human condition through plant science, and understanding how plants at every scale, from staple crops to overlooked nonvascular species, respond to a changing climate is central to that work. The review notes that current Earth system models, the tools scientists use to forecast future climate scenarios, rarely account for mosses separately from other vegetation, which can lead to inaccurate estimates of carbon uptake in northern forests and tundra. The authors argue that building moss-specific data into these models and continuing to study how species like Physcomitrium patens and Sphagnum respond to rising CO2 in natural settings will be essential to predicting whether peatlands and permafrost continue to store carbon or begin releasing it as the climate warms.