Earth’s poles are undergoing simultaneous freakish extreme heat with parts of Antarctica more than 70 degrees (40 degrees Celsius) warmer than average and areas of the Arctic more than 50 degrees (30 degrees Celsius) warmer than average.
The coldest location on the planet has experienced an episode of warm weather this week unlike any ever observed, with temperatures over the eastern Antarctic ice sheet soaring 50 to 90 degrees above normal. The warmth has smashed records and shocked scientists.
“This event is completely unprecedented and upended our expectations about the Antarctic climate system,” said Jonathan Wille, a researcher studying polar meteorology at Université Grenoble Alpes in France, in an email.
“Antarctic climatology has been rewritten,” tweeted Stefano Di Battista, a researcher who has published studies on Antarctic temperatures. He added that such temperature anomalies would have been considered “impossible” and “unthinkable” before they actually occurred.
Parts of eastern Antarctica have seen temperatures hover 70 degrees (40 Celsius) above normal for three days and counting, Wille said. He likened the event to the June heat wave in the Pacific Northwest, which scientists concluded would have been “virtually impossible” without human-caused climate change.
What is considered “warm” over the frozen, barren confines of eastern Antarctica is, of course, relative. Instead of temperatures being minus-50 or minus-60 degrees (minus-45 or minus-51 Celsius), they’ve been closer to zero or 10 degrees (minus-18 Celsius or minus-12 Celsius) — but that’s a massive heat wave by Antarctic standards.
The average high temperature in Vostok — at the center of the eastern ice sheet — is around minus-63 (minus-53 Celsius) in March. But on Friday, the temperature leaped to zero (minus-17.7 Celsius), the warmest it’s been there during March since record keeping began 65 years ago. It broke the previous monthly record by a staggering 27 degrees (15 Celsius).
“In about 65 record years in Vostok, between March and October, values above -30°C were never observed,” wrote Di Battista in an email.
Vostok, a Russian meteorological observatory, is about 808 miles from the South Pole and sits 11,444 feet above sea level. It’s famous for holding the lowest temperature ever observed on Earth: minus-128.6 degrees (minus-89.2 Celsius), set on July 21, 1983.
Temperatures running at least 50 degrees (32 Celsius) above normal have expanded over vast portions of eastern Antarctica from the Adélie Coast through much of the eastern ice sheet’s interior. Some computer model simulations and observations suggest temperatures may have even climbed up to 90 degrees (50 Celsius) above normal in a few areas.
Eastern Antarctica’s Concordia research station, operated by France and Italy and about 350 miles from Vostok, climbed to 10 degrees (minus-12.2 Celsius), its highest temperature on record for any month of the year. Average high temperatures in March are around minus-56 (minus-48.7 Celsius).
At a nearby weather station, the temperature reached 13.6 degrees (minus-10.2 Celsius) about 67 degrees (37 Celsius) above average, according to University of Wisconsin Antarctic researchers Linda Keller and Matt Lazzara.
Keller and Lazzara said in an email that such a high temperature is particularly noteworthy since March marks the beginning of autumn in Antarctica, rather than January, when there is more sunlight. At this time of year, Antarctica is losing about 25 minutes of sunlight each day.
Wille said the warm conditions over Antarctica were spurred by an extreme atmospheric river, or a narrow corridor of water vapor in the sky, on its east coast. According to computer models, the atmospheric river made landfall on Tuesday between the Dumont d’Urville and Casey Stations and dropped an intense amount of rainfall, potentially causing a significant melt event in the area.
The moisture from the storm diffused and spread over the interior of the continent. However, a strong blocking high pressure system or “heat dome,” moved in over east Antarctica, preventing the moisture from escaping. The heat dome was exceptionally intense, five standard deviations above normal.
The excessive moisture from the atmospheric river was able to retain large amounts of heat, while the liquid-rich clouds radiated the heat down to the surface — known as downward long-wave radiation.
Wille explained warm air is often transported over the Antarctic interior this way but not to this extent or intensity. “[T]his is not something we’ve seen before,” he said. “This moisture is the reason why the temperatures have gotten just so high.”
Models show the atmospheric river will exit the continent around Saturday, but the moisture will take longer to dissipate. Abnormally high temperatures in the region could last through the weekend.
The abnormally high temperatures have caused some melting in the region according to models, which is unusual as this part of Antarctica doesn’t experience much melt often. This one melt event won’t affect the stability of the glaciers in that area though.
“This event happened in a location that doesn’t often have melt. Obviously, this doesn’t mean that from now on we’re worried that melting will happen,” Wille said. “It’s more of like, ‘Oh, that is weird, that could happen more in the future and then this could be bad.’”
Wille said it’s difficult to attribute this one event to climate change at the moment, but he does think rising temperatures helped prime conditions for such an event. Climate change is “loading the dice” for more situations like this, he said.
Wille and his colleagues are studying how climate change will affect the circulation patterns around Antarctica and whether atmospheric rivers will become more common or more intense.
“We do believe they will become more intense because it just simple physics … but the details, we’re still trying to figure that out. It would be very difficult to say that there’s not a climate change fingerprint on an event like this,” he said.
Keller and Lazzara suggested more study is needed on the climate change connection.
“[W]e can’t tell whether this is going to be a new trend or is just an oddity that occurs occasionally on a most fascinating continent,” they wrote.
Temperatures are known to vary wildly over Antarctica, and massive swings are common. Contrasting with this warm spell over eastern Antarctica, the South Pole observed just observed its coldest April to September period on record last year, with an average temperature of minus-78 degrees (minus-61 Celsius).
But shortly after that historic bout of cold, the sea ice extent surrounding the continent shrunk to its smallest extent just last month.
Amid all of the variability in Antarctica, fingerprints of human-caused climate change are still evident. Its western ice sheet is losing mass while western parts of the continent and the peninsula are among the fastest-warming regions on Earth.
Warm ocean temperatures threaten to destabilize Antarctica’s Thwaites Glacier, a slab the size of Florida that contributes about 4 percent of annual global sea level rise.
The historically high temperatures in Antarctica follow a pulse of exceptional warmth on the planet’s opposite end. On Wednesday, temperatures near the North Pole catapulted 50 degrees above normal, close to the melting point.
Highs in the lower 30s (0 Celsius) are not terribly unusual in the summertime, but they’re far from the norm in winter. The mild temperatures are also accompanied by liquid rain at far northern latitudes, hastening the seasonal melting of sea ice.
“Looking back over the last few decades, we can clearly see a trend in warming, particularly in the ‘cold season’ in the Arctic,” Ruth Mottram, a climate scientist with the Danish Meteorological Institute, wrote in an email. “It’s not surprising that warm air is busting through into the Arctic this year. In general we expect to see more and more of these events in the future.”
Temperatures averaged over the high Arctic north of 80 degrees latitude are about 25 degrees (14 Celsius) above normal. Some forecast models indicate small areas in the Arctic, including near the North Pole, could experience temperatures as much as 45 to 54 degrees (25 to 30 Celsius) above normal Wednesday and Thursday.
In Hopen, an island off Svalbard in the Barents Sea at 76 degrees north latitude, the temperature recently hit 39 degrees (3.9 Celsius), its highest March temperature on record.
Mottram connected the intrusion of warm air to an atmospheric river — or concentrated jet of moisture — steered north by the bomb cyclone. A bomb cyclone is a storm or zone of low pressure that intensifies at breakneck speed.
The cyclone formed along the U.S. East Coast on Friday and Saturday, unleashing heavy snow and strong winds. Next, on Sunday and Monday, it tore through Atlantic Canada, where its pressure plummeted to that found at the core of Hurricane Sandy in 2012. Then it swept toward Greenland.
“It appears that a new record has been set for lowest pressure on record anywhere in Greenland at 934.1 hPa measured at the [Danish Meteorological Institute] station at Ikermiuarssuk,” Mottram said. The pressure reading hasn’t been officially certified as a record, but Mottram notes that it is consistent with other observations and model forecasts.
Average sea-level air pressure is closer to 1,000 hPa (hectoPascals); the resulting deficit was akin to removing 6.6 percent of the atmosphere’s mass from the middle of the storm — hence the strong inward winds aimed at “filling the void.” That entrained a strip of warm, moisture-rich air or atmospheric river that snaked poleward.
The NOAA HySplit model, which calculates the trajectories that air took to reach its destination, reveals that the air mass trucked north by the bomb cyclone curled east of Greenland and over Iceland during the weekend. Weather models indicate the same plume of warmth will reach the North Pole on Wednesday with temperatures between 29 and 33 degrees (near 0 Celsius).
It just so happens that a team of research scientists studying warm air intrusions has been stationed at Kiruna in northern Sweden waiting for an event like this. Since Saturday, they’ve been flying a specially outfitted German aircraft called HALO, or High Altitude and Long Range Research Aircraft, between the North Pole and the approaching warm plume. The parent study is known as HALO-(AC)³. It is being steered by researchers from the University of Leipzig in Germany and involves multiple European meteorological institutions.
“This is exactly the situation we aim to cover with the ongoing 6-weeks campaign,” the team said in a statement via email. “We are trying to put together some of the puzzle pieces of the so-called ‘Arctic Amplification’ (stronger warming of the Arctic compared to [mean] global warming). And warm air intrusions are actually one of the candidates to explain this phenomenon.”
The Arctic is warming three times faster than the rest of the planet, and atmospheric scientists are trying to better understand the processes contributing to such swiftly rising temperatures.
Thus far, the team has observed a number of phenomena that display telltale climate implications, many of which have been spurred by the sudden warm-up.
“For example, heavy rain over sea ice,” wrote the team. “This might have serious implications on a possible early melting of the sea ice, and this in the mid of March!”
The team also encountered tall convective clouds, or clouds energized by vertical heat transfer in the atmosphere. Some had blossomed almost as tall as clouds usually found in the tropics.
“Surface temperatures in the Fram Strait are currently more than 20 degrees Celsius higher than expected from the long-term records,” the team continued. “It is not just the intensity of the current warm air intrusion, but also the duration, which seems unusual. There are indications from forecast products that the sea ice will be seriously disturbed by this massive warming event.”
According to the National Snow and Ice Data Center, current sea ice extent, defined as the area with at least 15 percent sea ice coverage, is scraping the bottom of the barrel. At present, it’s on pace to fall below the record minimum set in summer of 2012, which may occur if current trends continue. About 14.6 million square kilometers are iced over, compared with a mid-March average of 15.5 million square kilometers.
Temperatures in the Arctic will fall to some extent by Thursday, but they look to remain unusually mild still over the next week.
The pulse of warmth over the Arctic is one of many that have swelled over the region in recent decades. A 2017 study found warm winter events in the Arctic are becoming more frequent and longer lasting. From 1980 to 2016, an additional six warming events occurred per winter at the North Pole, lasting on average 12 hours longer, compared with the period from 1893 to 1979.
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