The Southern Ocean, which acts as one of the natural world’s most effective sponges for absorbing carbon dioxide, is showing signs of an unexpected revival in its ability to do so, according to scientists.
The oceans absorb about a quarter of emissions caused by human activities, such as the burning of fossil fuels, reducing the speed of climate change. About 40 percent of this occurs in the Southern Ocean, which surrounds the Antarctic, making it the planet’s strongest ocean carbon sink.
The researchers said the new findings are surprising and remarkable.
Earlier studies had suggested that rising emissions caused by humans had brought about the saturation of the Southern Ocean in the 1980s. Researchers estimated that the efficiency of the Southern Ocean to absorb carbon dioxide had dropped by about 30 percent, which they put down to higher wind speeds across the area which brought carbon-rich waters to the surface. This was itself a consequence of climate change and the depletion of the ozone layer, they said, creating a feedback loop that would only get worse over time.
However, the new report published in the journal Science shows that this downward trend in capacity reversed in about 2002 and regained its former strength in line with rising emissions by 2012. The scientists put the change down to a combination of dropping water surface temperatures in the Pacific sector and a change in ocean circulation keeping carbon rich waters below those at the surface.
“A strong carbon sink in the Southern Ocean helps to mitigate climate change for the moment, as otherwise even more CO2 would have stayed in the atmosphere, but we cannot conclude that this will continue forever. One has to recognize that despite this remarkable increase in the Southern Ocean carbon sink, emissions have gone up even more,” said Nicolas Gruber, lead author and an environmental physicist.
The international team analyzed measurements of carbon dioxide in surface waters over a 30-year period from 1982. They compared this data with atmospheric carbon dioxide measurements and satellite observations.
Gruber said the new report did not contradict the findings of earlier studies, but did challenge the conclusions drawn from them, arguing that previous research had been largely dependent on models rather than observations.
“The models don’t do a particularly good job in modeling the Southern Ocean, so I would say this is much much stronger evidence. It is crucial that we continue to make these observations and analyze them to detect further changes in the uptake,” he said.
The research team say that it indicates that the ocean’s potential to absorb carbon dioxide fluctuates more over time than previously thought. Scientists have cautioned that future trends cannot be predicted reliably.
“This announcement is good news, on the face of it, because we want this enormous carbon sink to keep working efficiently. It is not any reason to be complacent, however, because we still understand rather little about the internal workings of the Southern Ocean carbon cycle. For this reason we cannot be sure how resilient the Southern Ocean carbon sink will be in the future,” said Toby Tyrrell, professor in earth system science in ocean and earth science at the University of Southampton.
Although the ocean acidification caused by the absorption of carbon dioxide has been shown to pose serious consequences for marine ecology, Tyrrell said such conclusions could not be drawn in relation to the new study.
“This extra carbon is unlikely to pose a large threat to life through ocean acidification. Most of the carbon taken up in the Southern Ocean is transported shortly afterwards to the deep ocean, where fewer organisms live,” he said.
CONFRONTATION: The water cannon attack was the second this month on the Philippine supply boat ‘Unaizah May 4,’ after an incident on March 5 The China Coast Guard yesterday morning blocked a Philippine supply vessel and damaged it with water cannons near a reef off the Southeast Asian country, the Philippines said. The Philippine military released video of what it said was a nearly hour-long attack off the Second Thomas Shoal (Renai Shoal, 仁愛暗沙) in the contested South China Sea, where Chinese ships have unleashed water cannons and collided with Philippine vessels in similar standoffs in the past few months. The China Coast Guard and other vessels “once again harassed, blocked, deployed water cannons, and executed dangerous maneuvers” against a routine rotation and resupply mission to
GLOBAL COMBAT AIR PROGRAM: The potential purchasers would be limited to the 15 nations with which Tokyo has signed defense partnership and equipment transfer deals Japan’s Cabinet yesterday approved a plan to sell future next-generation fighter jets that it is developing with the UK and Italy to other nations, in the latest move away from the country’s post-World War II pacifist principles. The contentious decision to allow international arms sales is expected to help secure Japan’s role in the joint fighter jet project, and is part of a move to build up the Japanese arms industry and bolster its role in global security. The Cabinet also endorsed a revision to Japan’s arms equipment and technology transfer guidelines to allow coproduced lethal weapons to be sold to nations
Thousands of devotees, some in a state of trance, gathered at a Buddhist temple on the outskirts of Bangkok renowned for sacred tattoos known as Sak Yant, paying their respects to a revered monk who mastered the practice and seeking purification. The gathering at Wat Bang Phra Buddhist temple is part of a Thai Wai Khru ritual in which devotees pay homage to Luang Phor Pern, the temple’s formal abbot, who died in 2002. He had a reputation for refining and popularizing the temple’s Sak Yant tattoo style. The idea that tattoos confer magical powers has existed in many parts of Asia
ON ALERT: A Russian cruise missile crossed into Polish airspace for about 40 seconds, the Polish military said, adding that it is constantly monitoring the war to protect its airspace Ukraine’s capital, Kyiv, and the western region of Lviv early yesterday came under a “massive” Russian air attack, officials said, while a Russian cruise missile breached Polish airspace, the Polish military said. Russia and Ukraine have been engaged in a series of deadly aerial attacks, with yesterday’s strikes coming a day after the Russian military said it had seized the Ukrainian village of Ivanivske, west of Bakhmut. A militant attack on a Moscow concert hall on Friday that killed at least 133 people also became a new flash point between the two archrivals. “Explosions in the capital. Air defense is working. Do not