20-year study of climate change impact on permafrost forests could refine carbon source and CO₂ sink models

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Micrometeorological observation tower in Alaska. The tower installed in a black spruce forest on permafrost in Fairbanks, Alaska, monitors CO2 exchange and environmental conditions in 30-minute intervals. Credit: Osaka Metropolitan University

In perhaps the first long-term study of CO2 fluxes in northern forests growing on permafrost, an Osaka Metropolitan University-led research team has found that climate change increased not only the sources of carbon, but also the CO2 sinks.

The 20-year observation from 2003–2022 in the interior of Alaska showed that while CO2 sinks turned into sources during the first decade, the second decade showed a nearly 20% increase in CO2 sinks.

The findings are published in the Proceedings of the National Academy of Sciences.

Graduate School of Agriculture Associate Professor Masahito Ueyama and colleagues found that warming led to wetness, which in turn aided the growth of black spruce trees. During photosynthesis, the growing trees were using the increasing CO2 released from human activities.

Carbon dioxide budget from black spruce forest on permafrost in Alaska. Credit: Osaka Metropolitan University

"The 20 years of observational data that we have is, as far as we know, the longest record of such research on permafrost forests in the world," Professor Ueyama said.

"However, since it is difficult to apply the findings and data from those 20 years to a future world in which warming continues, further long-term observations are needed. But we hope that our findings will help verify and improve the accuracy of warming prediction models."

More information: Masahito Ueyama et al, Anomalous wet summers and rising atmospheric CO 2 concentrations increase the CO 2 sink in a poorly drained forest on permafrost, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2414539121

Journal information: Proceedings of the National Academy of Sciences

Provided by Osaka Metropolitan University