The tundra, the typical vegetation of Arctic polar regions, has been rapidly expanding—not just recently, but since the beginning of the last century. This was revealed by an international study coordinated by the Institute of Polar Sciences of the National Research Council of Italy (CNR-ISP), in collaboration with the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, and the ENI-CNR Joint Research Center. According to the research, which was featured on the cover of Nature Communications Earth & Environment for its photographic contributions, the phenomenon is closely linked to the reduction of sea ice cover and the retreat of glaciers.
“Through the analysis of chemical signatures from a marine sediment archive collected at extreme latitudes in the Svalbard Islands, Norway, we identified signals indicative of a significant change in tundra coverage during the climatic transition from the Little Ice Age (1400–1900 AD) to the last 100 years, coinciding with the current anthropogenic warming,” explains Tommaso Tesi, a researcher at CNR-ISP and coordinator of the study. “This research represents the first reconstruction that directly links the reduction of sea ice and glacier retreat to the expansion of vegetation in Svalbard. The drastic decline in sea ice extent recorded since the early 20th century has coincided with an increase in terrestrial vegetation, suggesting a strong tundra expansion in areas previously covered by ice. Furthermore, the results show that the rapid expansion of the tundra peaked around the 1990s, in parallel with the acceleration of global warming and the rapid collapse of the Arctic cryosphere.”
The ‘greening’ phenomenon has also led to a shift in plant community composition, as documented through geochemical analyses. “Initially, the land surfaces exposed by the retreating glaciers were colonized by mosses and lichens, typical of the tundra. Later, as organic matter accumulated and soil conditions improved, vascular plants (plants with roots, stems, and leaves) began to establish themselves,” continues Gianmarco Ingrosso, a researcher at the Institute of Research on Terrestrial Ecosystems (CNR-IRET) and the study’s first author. “Among the plant species that seem to benefit the most from the new climatic conditions, Salix polaris, a small shrub adapted to milder conditions, is playing a key role in gradually expanding its range.”
This complex scenario raises important questions within the scientific community regarding the ecological balance of the Arctic. “On one hand, the increase in vegetation cover could enhance atmospheric carbon sequestration, but on the other hand, such a drastic change in areas previously covered by glaciers could have significant consequences on biogeochemical cycles and the distribution of native wildlife,” the CNR researchers conclude. “Moreover, the thawing of permafrost, accelerated by rising temperatures, could release large amounts of greenhouse gases into the atmosphere, counteracting the benefits of increased plant biomass. In this case, the expansion of vegetation in the Arctic and a progressively ‘greener’ environment serve as a serious warning signal for fragile polar ecosystems.”
The study is part of the PAIGE (Chronologies for Polar Paleoclimate Archives – Italian-German Partnership) and ENI-CNR Joint Research Agreement projects. It represents a step forward in understanding the complex dynamics that regulate the interaction between climate, the cryosphere, and terrestrial ecosystems. The innovative approach based on plant markers has helped fill a significant knowledge gap regarding the history of Arctic greening, offering a unique perspective on how the tundra is responding to ongoing climate change and the potential future developments of polar ecosystems.