Climate change increases sources of carbon and CO2 sinks

The carbon dioxide budget of ecosystems in high-latitude regions may be altered by accelerated warming, shifts in the hydrological cycle, and increasing levels of atmospheric CO2.

In what is likely the first long-term investigation of CO2 fluxes in northern forests situated on permafrost, a research group led by Osaka Metropolitan University has discovered that climate change has not only amplified carbon emission sources, but also enhanced CO2 sinks.

Over a 20-year observation period from 2003 to 2022 in interior Alaska, researchers discovered that although CO2 sinks transitioned to sources during the initial decade, a remarkable nearly 20% increase in CO2 sinks was observed in the subsequent decade.

Led by Associate Professor Masahito Ueyama from the Graduate School of Agriculture, the team found that rising temperatures resulted in increased wetness, which subsequently promoted the growth of black spruce trees.

As these trees grew, they utilized the rising levels of CO2 produced by human activities during their photosynthesis process.

“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 proclaimed. “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.”

Journal reference:

1. Masahito Ueyama, Hiroki Iwata, Hirohiko Nagano, Naoki Kukuu, and Yoshinobu Harazono. Anomalous wet summers and rising atmospheric CO2 concentrations increase the CO2 sink in a poorly drained forest on permafrost. Proceedings of the National Academy of Sciences, 2024; DOI: 10.1073/pnas.2414539121