In March of last year, an extreme heatwave struck Eastern Antarctica, causing the most anomalous temperatures ever recorded compared to the local climate. This unprecedented event was the result of a highly unusual weather pattern, which brought strong northward winds and imported warm, moist air from Australia.
Weather forecasting models skillfully predicted the heatwave up to 8 days in advance. While the heatwave occurred shortly after the record low sea ice extent in February, the surface temperature anomalies in the Southern Ocean had a minimal impact on the magnitude of the heatwave.
Recently, a group of researchers from the Department of Atmospheric Sciences at the University of Washington in Seattle, USA, made an intriguing discovery. They found that a widely used climate model fails to simulate heatwaves of this magnitude accurately. However, when the model’s free atmosphere winds are adjusted to match the observed winds, it can simulate a heatwave more closely resembling the recorded event. The specialists suggested that improving the model’s atmospheric circulation variability would lead to better simulation of heatwaves.
Among the findings, there is an unexpected and growing phenomenon in Antarctica. The continent is experiencing a rapid flowering, signaling inaccuracies in previous predictions made by the models. These findings have just been published in Advancing Earth and Space Sciences.
The Antarctic Peninsula is home to only two native plant species capable of blooming. Scientists have now identified that these plants are growing at an unprecedented rate as temperatures rise and ice begins to melt. The Antarctic hair grass has grown as much in the past decade (2009-2019) as it did in the preceding 50 years. Similarly, the Antarctic pearlwort has quintupled its growth during the same period. The research team measured the growth of these native plants at Signy Island in the South Orkney Islands.
The results were clear: not only have the sites experienced faster growth, but they have also become more densely populated with plants every year as the climate warms up.
According to the nonprofit organization Discovering Antarctica, the region’s temperatures have risen by an average of 3°C due to human-induced climate change. This means that once-stable ice platforms are now retreating, creating habitable land for both plant species.
“The most remarkable feature of this is not the idea that something is growing faster. It’s that we believe we are starting to see what is almost a radical change or a tipping point,” stated Edward Blanchard-Wrigglesworth, the lead author of the study. “The accelerated expansion is now clearly evident in the region. This research provides us with the first comprehensive dataset showing how fast and how densely a plant community can expand.”
The March 2022 Antarctic heatwave recorded the warmest temperature anomaly ever observed. It was the result of extreme atmospheric heat fluxes. The thermodynamic amplification was 2°C, and according to the researchers’ calculations, equivalent heatwaves could increase by an additional 5 to 6°C by 2100.
The specialists acknowledged that there could be other factors at play in the plant’s growth, such as the decrease in the population of Antarctic fur seals. However, this, too, is linked to climate change.
Meanwhile, as the Antarctic land becomes more habitable, invasive species could also colonize the continent and outcompete native plants, potentially destabilizing long-established local ecosystems.
“If we extrapolate what we observe at Signy Island to other sites in Antarctica, a similar process could occur. This means that the landscape and biodiversity of the region could undergo rapid changes,” concluded the researchers.
