The global climate is warming, and Earth’s polar regions are feeling the effects. A new study of the South Orkney Islands shows that the region has warmed significantly since the 1950s. The rise in warming in the South Orkneys exceeds the overall global warming.
As the islands warm, plant life is spreading.
The South Orkney Islands lie about 600 km (375 miles) northeast of the Antarctica Peninsula’s tip. Britain and Argentina both lay claim to the group of islands. Both nations maintain research stations in the South Orkneys: Argentina has one on Laurie Island and Britain has one on Signy Island.
A study based on Signy Island data going back to the 1950s shows that the climate is warming and that the spread of vascular plants in the warming conditions is turning more of the island green, especially since 2009. The study is “Acceleration of climate warming and plant dynamics in Antarctica,” published in the journal Current Biology. The lead author is Nicoletta Cannone from the Università degli Studi dell’Insubria, Dip. Scienza e Alta Tecnologia, Italy.
While the South Orkneys are separated from Antarctica by about 600 km, they’re still in a polar climate. About 90% of the islands were glaciated as of 2009, and the summers are very short and very cold. Ice-covered seas surround the South Orkneys seas from late April to November.
But the new study shows that things are changing in these remote islands. According to the paper, the two species of vascular plants on Signy Island responded to the climate change acceleration with a “striking advance,” according to the report.
“This is the first evidence in Antarctica for accelerated ecosystem responses to climate warming, confirming similar observations in the Northern Hemisphere.”
From “Acceleration of climate warming and plant dynamics in Antarctica” by Cannone et al. 2022
The warming hasn’t been a continuous trend. There was one period of pronounced cooling in the years since the study began. The study points out that “… a short but intense cooling occurred from the Antarctic Peninsula to the South Orkney Islands…” between 1999 and 2016.
But air temperature warming resumed in 2012 on Signy Island, accelerating the expansion of the two vascular plant species. “We also hypothesize that the “pulse” climatic event of the strong air cooling detected in 2012 did not appear to influence the vegetation community dynamics on this island,” the authors write. “The lack of negative impacts of the strong pulse cooling event in 2012 on both species could be explained by their ability to perform photosynthesis at low ambient temperatures.”
This figure from the study shows the Summer Air Temperature at Signy Island. Blue dots are SAT between 1960 and 2011, and orange dots are SAT between 2012 and 2018. Image Credit: Cannone et al. 2022.
Other research shows that the same type of accelerated ecosystem responses from climate warming occurs in the Arctic. A 2018 research article reported that plants are increasing their northern range in the Arctic and getting taller. A 2020 paper showed that the warming climate creates terrestrial algae blooms in Antarctica. But the authors of this paper say theirs is the first research to document the advance of vascular plants in the Antarctic. They also say that ongoing climate change will significantly affect the region.
“This is the first evidence in Antarctica for accelerated ecosystem responses to climate warming, confirming similar observations in the Northern Hemisphere,” they explain in their paper. “Our findings support the hypothesis that future warming will trigger significant changes in these fragile Antarctic ecosystems.”
There are two species of vascular plants native to Signy Island. One is D. antarctica, a flowering plant known as Antarctic Hair Grass. The other is C. quitensis, another flowering plant that’s also called Antarctic Pearlwort.