(CN) — New research finds that the South Pole has heated up at three times the global average since 1989 due to changing temperatures in tropical seas and likely intensified by greenhouse gas emissions.
This is a drastic contrast to the stable and slightly cooling surface temperatures scientists observed at Earth’s southernmost point during much of the late 20th century, which had suggested resilience to a rapidly industrializing — and carbon-soaked — planet.
The research, published Monday in the journal Nature Climate Change, depicts the latest chapter in the South Pole’s history of whiplashing temperatures after the steadiness recorded from 1957 until the 1980s.
Data collected from the Amundsen-Scott weather observatory, established on the Antarctic Plateau in 1957, shows that the 1.8 degrees Celsius rise between 1989 and 2018 was the South Pole’s warmest 30-year trend on record.
“We thought that the plateau was mostly governed by these steady westerly winds around East Antarctica, which is in the South Atlantic and the Indian Ocean, and that seemed to keep the plateau stable,” Kyle Clem, the geographer who led a team of seven scientists in studying weather data from the South Pole, said in an interview. “And while global temperatures were increasing, the plateau was stable — it was even cooling — so it seemed like this area might be immune to warming. And it’s not.”
Clem and his fellow researchers took the weather station’s data, plotted the trends and plugged these observations into climate models to analyze warming in the region.
“These are massive multidecadal flips that are inherent to the interior Antarctic continent, and these are some of the most extreme multidecadal flips, or variability, in the world,” he said.
But how did the South Pole start experiencing such uncharacteristic warming? West Antarctica is dominated by intense low-pressure systems in the South Pacific, Clem explained, which tend to bring warmer air to West Antarctica and the Antarctic Peninsula.
“While we typically have really strong low-pressure systems in the South Pacific that warm the Antarctic Peninsula and West Antarctica, these have shifted eastward into the Weddell Sea, which is in the South Atlantic, and these have been transporting warm air from the South Atlantic onto the plateau,” Clem said. “This has been the primary mechanism for bringing the warming in, and this is just amplified by the broader, global-scale, anthropogenic warming.”
Clem and his team noticed that, as the South Pole was warming, so was the western tropical Pacific. They found that warm ocean temperatures there caused more tropical thunderstorms, setting off an atmospheric wave pattern that propagated across the South Pacific and toward Antarctica. As a result, the Weddell Sea has experienced stronger low-pressure systems that tap into the South Atlantic’s warmer air, transporting it to the Antarctic Plateau.
Accordingly, the South Pole saw a climb of 0.6 degrees Celsius each decade since 1989, compared to the global rate of 0.2 degrees Celsius, according to the study.
“From the data, it would appear that these are mostly natural [changes], because during the 20th century, when global temperatures were increasing, the South Pole was cooling. So it has its own internal variability that can actually hide anthropogenic warming,” Clem said. “But when it flips, it works in tandem with anthropogenic warming, and that gives rise to really extreme warming.”
But the exact extent to which human-caused climate change played a role in warming the South Pole is difficult to pinpoint, thanks in large part to Antarctica’s extreme volatility.
“We analyzed over 252 climate model simulations … with and without anthropogenic greenhouse gases and we found that the observed warming of 1.8 degrees in 30 years exceeds 99.9% of all possible 30-year temperature trends at the South Pole that occur without anthropogenic greenhouse gases,” Clem said. “Our major conclusion from this study, from the data that we analyzed, is that natural, multidecadal climate swings are so extreme in this part of the world that they actually overwhelm the anthropogenic signal. That does not mean that anthropogenic climate change didn’t play a role.”