Antarctic 3x warming – ‘complicated’ link to climate change

A study led by Kyle Clem from Victoria University has found that the South Pole is warming nearly three times faster than the global average. This is linked to tropical variability, and the complexity may be related to climate change but may also help mask it.

The study: Record warming at the South Pole during the past three decades

Over the last three decades, the South Pole has experienced a record-high statistically significant warming of 0.61 ± 0.34 °C per decade, more than three times the global average. Here, we use an ensemble of climate model experiments to show this recent warming lies within the upper bounds of the simulated range of natural variability.

The warming resulted from a strong cyclonic anomaly in the Weddell Sea caused by increasing sea surface temperatures in the western tropical Pacific. This circulation, coupled with a positive polarity of the Southern Annular Mode, advected warm and moist air from the South Atlantic into the Antarctic interior.

These results underscore the intimate linkage of interior Antarctic climate to tropical variability. Further, this study shows that atmospheric internal variability can induce extreme regional climate change over the Antarctic interior, which has masked any anthropogenic warming signal there during the twenty-first century.

A lot of detail follows, but it is explained more simply – Klem Kyle (ZME Science): Antarctica is warming three times faster than the rest of the world

Climate scientists long thought Antarctica’s interior may not be very sensitive to warming, but our research, published today, shows a dramatic change.

Over the past 30 years, the South Pole has been one of the fastest changing places on Earth, warming more than three times more rapidly than the rest of the world.

My colleagues and I argue these warming trends are unlikely the result of natural climate variability alone. The effects of human-made climate change appear to have worked in tandem with the significant influence natural variability in the tropics has on Antarctica’s climate. Together they make the South Pole warming one of the strongest warming trends on Earth.

Scientists have been tracking temperature at the Amundsen-Scott South Pole Station, Earth’s southernmost weather observatory, since 1957. It is one of the longest-running complete temperature records on the Antarctic continent.

Our analysis of weather station data from the South Pole shows it has warmed by 1.8℃ between 1989 and 2018, changing more rapidly since the start of the 2000s. Over the same period, the warming in West Antarctica suddenly stopped and the Antarctic Peninsula began cooling.

One of the reasons for the South Pole warming was stronger low-pressure systems and stormier weather east of the Antarctic Peninsula in the Weddell Sea. With clockwise flow around the low-pressure systems, this has been transporting warm, moist air onto the Antarctic plateau.

South Pole warming linked to the tropics

Our study also shows the ocean in the western tropical Pacific started warming rapidly at the same time as the South Pole. We found nearly 20% of the year-to-year temperature variations at the South Pole were linked to ocean temperatures in the tropical Pacific, and several of the warmest years at the South Pole in the past two decades happened when the western tropical Pacific ocean was also unusually warm.

We know from earlier studies that strong regional variations in temperature trends are partly due to Antarctica’s shape.

The East Antarctic Ice Sheet, bordered by the South Atlantic and Indian oceans, extends further north than the West Antarctic Ice Sheet, in the South Pacific. This causes two distinctly different weather patterns with different climate impacts.

More steady, westerly winds around East Antarctica keep the local climate relatively stable, while frequent intense storms in the high-latitude South Pacific transport warm, moist air to parts of West Antarctica.

Scientists have suggested these two different weather patterns, and the mechanisms driving their variability, are the likely reason for strong regional variability in Antarctica’s temperature trends.

Our analysis reveals extreme variations in South Pole temperatures can be explained in part by natural tropical variability.

These climate model simulations reveal the remarkable nature of South Pole temperature variations. The observed South Pole temperature, with measurements dating back to 1957, shows 30-year temperature swings ranging from more than 1℃ of cooling during the 20th century to more than 1.8℃ of warming in the past 30 years.

This means multi-decadal temperature swings are three times stronger than the estimated warming from human-caused climate change of around 1℃.

The temperature variability at the South Pole is so extreme it currently masks human-caused effects. The Antarctic interior is one of the few places left on Earth where human-caused warming cannot be precisely determined, which means it is a challenge to say whether, or for how long, the warming will continue.

But our study reveals extreme and abrupt climate shifts are part of the climate of Antarctica’s interior. These will likely continue into the future, working to either hide human-induced warming or intensify it when natural warming processes and the human greenhouse effect work in tandem.

So climate changes in the Antarctic are complex and linked to tropical variations, particularly in the South Pacific.

Movement of warm air from the tropics to Antarctica and cold air from Antarctica to the tropics affects New Zealand’s weather and climate.

We’ve been getting a sustained blast of Antarctic air over the past few days and that looks likely to continue through the week, with the next seven day highs predicted to be 8-11 degrees, with lows 4-6 degrees (in Dunedin). It’s deep winter so this isn’t out of the ordinary – except that so far this year snow hasn’t come to much, less than normal, but there’s plenty of winter to go.

While the study shows a rise in temperature at the South Pole since the early seventies it also shows more variability (which is one of the predicted effects of climate change):

Temperature and pressure changes at the South Pole during the modern instrumental record. a,b, Time series of the standardized South Pole annual-mean SAT (a) and running 30-yr SAT trends (°C decade−1) (b), with the 95% CI shaded in grey.

Leave a comment

2 Comments

  1. Duker

     /  1st July 2020

    The real answer is its unrelated to global warming, but that on its own wouldnt get published and the authors careers would suffer if they left it at that. Hence the playing around with climate models to ‘prove’ there was some there there.

    Reply
  2. Pink David

     /  1st July 2020

    Everywhere on earth is warming much faster than the average.

    Reply

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