In the study, it was observed that the warming of the air and soil, as well as soil drying, increased carbon release from tundra ecosystems

The warming climate shifts the dynamics of tundra
environments, according to a new study published in Nature. These changes could
transform tundras from carbon sinks into a carbon source, exacerbating the effects
of climate change.

A team of over 70 scientists used open-top
chambers (OTCs) to experimentally simulate the effects of warming on 28 tundra sites
around the world. OTCs basically serve as mini-greenhouses, blocking wind and
trapping heat to create local warming. 

The warming
experiments led to a 1.4°C increase in air temperature and a 0.4°C increase in soil
temperature, along with a 1.6% drop in soil moisture. These changes boosted
ecosystem respiration by 30% during the growing season, causing more carbon to be
released because of increased metabolic activity in soil and plants. The changes
persisted for at least 25 years after the start of the experimental warming – which
earlier studies hadn’t revealed.

– We knew from earlier studies
that we were likely to find an increase in respiration with warming, but we found a
remarkable increase – nearly four times greater than previously estimated, though it
varied with time and location, says Sybryn Maes of Umeå University, the study’s lead
author.

The increase in ecosystem respiration also varied with
local soil conditions, such as nitrogen and pH levels. This means that differences
in soil conditions and other factors lead to geographic differences in the response
– some regions will see more carbon release than others. Understanding the links
between soil conditions and respiration in response to warming is important for
creating better climate models. 

– Our work represents
the first assessment of ecosystem respiration response to experimental warming
across such a broad environmental gradient in the tundra, incorporating a
comprehensive set of environmental drivers, says Professor Ellen Dorrepaal of Umeå
University. 

"Maaperän A warming chamber and carbon analyzer to measure ecosystem
carbon fluxes help to understand how tundras will respond to our changing climate.
Photo: Anne Tolvanen

The study combines field data
from a total of 56 experiments, which offers a broader perspective across the whole
tundra area, and helps determining which environmental drivers are the key
determinants behind increased ecosystem respiration. Some areas, particularly parts
of Siberia and Canada, exhibit greater sensitivity to warming. 

The University of Lapland, Arctic Centre, contributed to the study with
data from three warming experiments. Current and former researchers Sari Stark,
Maria Väisänen, Henni Ylänne, and Eero Myrsky focus on the significance of global
changes on ecosystem functions and their climatic feedbacks. Other Finnish partners
include the Natural Resource Institute Finland, Aalto University, the University of
Helsinki, the University of Eastern Finland, the University of Oulu.

The original article in Nature:
Maes,
S. L. et al. (2024). Environmental drivers of increased ecosystem respiration in a
warming tundra. NATURE (in press). doi: 10.1038/s41586-024-07274-7

Additional reading:
Tundra flux database –
https://www.tundrafluxdatabase.com/
International Tundra Experiment –
https://www.gvsu.edu/itex/

Contact:
Dr. Sybryn Maes 
Department of Ecology and
Environmental Science, Umeå University, Abisko, Sweden Department of Earth and
Environmental Sciences, KU Leuven, Leuven, Belgium
Tel: +32 478 50 52
64
E-mail: sybryn.maes@gmail.com

Contact person
at the Arctic Centre at the University of Lapland:
University researcher
Sari Stark
sari.stark(at)ulapland.fi, +358 40 484 4254