We've known for decades that Earth as a whole is getting hotter. We've also known the heat has devastating effects on Antarctica and its massive sheets of ice. What we didn't know was just how hot things were getting down at the South Pole. According to research published this week in the journal Nature Climate Change, the region has been warming at more than three times the global average for the last 30 years.
Scientists have known for a while that there is at least some warming occurring in the Antarctic. In fact, earlier this year, the region experienced its hottest temperature ever recorded, breaking 20 degrees Celsius (68 degrees Fahrenheit) for the first time ever. But there was belief that perhaps the concentrated cold at the South Pole could potentially withstand some of the global trends, a theory often backed by pointing out that Antarctica sometimes sees an increase in the amount of sea ice produced even as regions like the Arctic continue to see ice melt.
But it appears that even the valleys of Antarctica’s ice sheet, which regularly reach temperatures below -100 degrees Celsius, are not immune from climate change. Researchers found that over the 30-year period from 1989 to 2018, the South Pole has warmed about 1.8 degrees Celsius at a rate of about 0.6 degrees Celsius per decade.
The fact that the South Pole is warming at such a significant rate marks a dramatic shift for the region. While much of the planet started to experience a global temperature rise during the 1970s and 1980s, the South Pole was actually experiencing a period of cooling and saw its average temperature drop by a full degree. Scientists believe that the cooling period was part of a natural climate pattern, which occurs in 20- to 30-year cycles. The nearly two-degree temperature rise that the region has experienced over the last three decades, however, does not appear to be the same natural ebb and flow that caused the cooling. Instead, it appears to be linked to climate change.
The main cause of warming, according to researchers, seems to be the increasing sea surface temperatures. As the oceans have gotten warmer, they have carried warm air to the South Pole. Even seemingly distant bodies of water heating up can carry change all the way down to the most remote part of the planet. A climate phenomenon known as Interdecadal Pacific Oscillation (IPO) can carry surface sea-level temperatures for periods of 20 to 30 years. It's the same phenomenon that can often strengthen tropical storms and hurricanes, and it also brings warm weather down to the South Pole through a wind system called the Southern Annular Mode (SAM). Those tropic temperatures, along with the still-healing hole in the Ozone layer above Antarctica combine with the greenhouse gases put into the atmosphere by humans to heat up the South Pole.
Not much is known about the history of temperatures at the South Pole. There are only records in the region dating back to 1957, so drawing conclusions or identifying historical trends is a challenge. It also makes it hard to pin the warming entirely on humans. But modeling performed by the scientists suggests that the level of temperature rise they record over the last 30 years is incredibly uncommon. According to researchers, the 1.8 degrees of warming was more than what occurred in 99.9 percent of all 30-year simulations that excluded human influence.