Study: Melting Ice Could Slow Vital Antarctic Ocean Current

The world's strongest ocean current could slow as melting Antarctic ice sheets flood it with fresh water, according to new research. Juan BARRETO / AFP
The world's strongest ocean current could slow as melting Antarctic ice sheets flood it with fresh water, according to new research. Juan BARRETO / AFP
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Study: Melting Ice Could Slow Vital Antarctic Ocean Current

The world's strongest ocean current could slow as melting Antarctic ice sheets flood it with fresh water, according to new research. Juan BARRETO / AFP
The world's strongest ocean current could slow as melting Antarctic ice sheets flood it with fresh water, according to new research. Juan BARRETO / AFP

The world's strongest ocean current could slow as melting Antarctic ice sheets flood it with fresh water, according to research published on Monday that warned of "severe" climate consequences.

Scientists used one of Australia's most powerful supercomputers to model how melting ice sheets might change the Antarctic Circumpolar Current, which plays a major role in global climate patterns.

If fossil fuel emissions increased over the next 25 years -- a so-called high emissions scenario -- the current could slow by around 20 percent, the peer-reviewed research found.

"The ocean is extremely complex and finely balanced," said University of Melbourne scientist Bishakhdatta Gayen.

"If this current 'engine' breaks down, there could be severe consequences, including more climate variability -- with greater extremes in certain regions, and accelerated global warming due to a reduction in the ocean's capacity to act as a carbon sink."

The Antarctic Circumpolar Current acted as a kind of "ocean conveyor belt" shifting immense columns of water through the Indian, Atlantic and Pacific Oceans, Gayen said.

Melting ice sheets would "dump vast quantities of fresh water" into the current, the modelling found.

This would change the ocean's salt content, making it harder for cold water to circulate between the surface and the depths.

Oceans play vital roles as climate regulators and carbon sinks.

Cooler waters can absorb greater amounts of heat from the atmosphere.

The strength of the current -- which flows clockwise around Antarctica -- also acts as a barrier that stops invasive species washing up on the continent's shores.

Algae and molluscs could more easily colonize Antarctica if the current slowed down, the researchers wrote.

Even if global warming was limited to a threshold of 1.5 degrees Celsius, the Antarctic current could still slow down.

"The 2015 Paris Agreement aimed to limit global warming to 1.5 degrees Celsius above pre-industrial levels," said climate scientist and co-author Taimoor Sohail.

"Many scientists agree that we have already reached this 1.5 degree target, and it is likely to get hotter, with flow-on impacts on Antarctic ice melting."

The research team, which included scientists from Australia, India and Norway, noted that their findings contrasted with previous studies that observed the current speeding up.

They said further observation and modelling was needed to understand how the "poorly observed region" was responding to climate change.

The research was published in the Environmental Research Letters journal.



Aloha, Bavaria! Munich Surfers Riding Wild River Wave Again

Aloha, Bavaria! Munich Surfers Riding Wild River Wave Again
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Aloha, Bavaria! Munich Surfers Riding Wild River Wave Again

Aloha, Bavaria! Munich Surfers Riding Wild River Wave Again

Surfing enthusiasts have cheered the reopening of a beloved whitewater site in downtown Munich, the German city better known for partying at Oktoberfest than splashing in the waves.

The Eisbach ("ice brook") standing wave in the city's Englischer Garten park was closed after tragedy struck in April when a 33-year-old woman drowned during a nighttime winter surf.

After a safety review and a petition to keep it open, the site -- just a stone's throw from an art museum and shopping streets -- was reopened by authorities in recent weeks.

Putting on a wetsuit and taking a board out of its bag after a day's work, Moritz, 43, said he's a regular at the surf spot on an arm of the Isar river.

"It's amazing. A wave right in the city center is something very special," he said. "I missed it during the closure."

Nearby, surfers performed tricks with virtuosity on the powerful wave, formed by the presence of rocks on the riverbed near a bridge.

"It's completely different from the ocean," said Moritz.

"Even if you know how to surf very well in the sea, you don't necessarily know how to do it here where the water comes from the front and not from behind."

Another surfer, Irina, 34, said she tries to come three times a week, "before work, because it gives you energy".

She finds "the power of the wave is good" and said she feels safe at this unique spot, even if "there are rocks at the bottom and you have to be a little careful when you fall".

A German surfer lost her life during a night session in April after being trapped underwater for nearly 30 minutes, her leash caught on an unidentified object.

Friends and emergency services rushed to help her, but she died a week after her accident.

An investigation found no safety breaches on the part of the city or state, which had always warned surfers to attempt the challenge "at their own risk".

New guidelines have, however, been issued: night surfing is banned between 10:00 pm and 5:30 am, and the minimum age for braving the wave is 14.

Surfers must also use a system that allows their leash to be detached in case of emergency.

These rules are "largely reasonable", said Franz Fasel, head of the local surfers' association IGSM, who said between 3,000 and 5,000 local surfers use the Eisbach site.

"Surfing is simply part of the lifestyle in Munich," he said. "Not just for the surfers themselves, but also for the city's image."

It was not always this way. In the past, the Eisbach wave was entirely natural and surfable only occasionally, for example, when gravel accumulated in the riverbed.

Surfers took matters into their own hands in the 1980s, installing a river crossing and adding objects to improve the wave, not all well received by the authorities.

The site is now promoted by the tourist office as one of Munich's top attractions.

Bavaria's state premier Markus Soeder proudly declared during a recent visit that "Munich is a surfer's paradise" and Bavaria "a bit like the California of Germany".