How global warming affects oceans
Washington: A new study has shown how climate change has put a freshwater lid on the Antarctic ocean, trapping warm water in ocean depths.
In the mid-1970s, the first available satellite images of Antarctica during the polar winter revealed a huge ice-free region within the ice pack of the Weddell Sea. This ice-free region, or polynya, stayed open for three full winters before it closed.
Subsequent research showed that the opening was maintained as relatively warm waters churned upward from kilometres below the ocean`s surface and released heat from the ocean`s deepest reaches. But the polynya-which was the size of New Zealand-has not reappeared in the nearly 40 years since it closed, and scientists have since come to view it as a naturally rare event.
Now, however, a study led by researchers from McGill University suggests a new explanation: The 1970s polynya may have been the last gasp of what was previously a more common feature of the Southern Ocean, and which is now suppressed due to the effects of climate change on ocean salinity .
The McGill researchers, working with colleagues from the University of Pennsylvania, analyzed tens of thousands of measurements made by ships and robotic floats in the ocean around Antarctica over a 60-year period.
Their study shows that the ocean`s surface has been steadily getting less salty since the 1950s. This lid of fresh water on top of the ocean prevents mixing with the warm waters underneath. As a result, the deep ocean heat has been unable to get out and melt back the wintertime Antarctic ice pack.
"Deep ocean waters only mix directly to the surface in a few small regions of the global ocean, so this has effectively shut one of the main conduits for deep ocean heat to escape," Casimir de Lavergne, a recent graduate of McGill`s Master`s program in Atmospheric and Oceanic Sciences and lead author of the paper, said.
The study is published in the journal Nature Climate Change.
More from India
More from World
More from Sports
More from Entertaiment
- Revealed - How Indian Army hit terror camps across LoC!
- Pak forces will teach Zee News what real surgical strike is: Hafiz Saeed
- India used 'Cartosat 2c' satellite in surgical strikes against Pakistan
- Panel discussion on Hafiz Saeed's reaction after Indian Army surgical strikes
- DNA: Inside story of Indian Army's surgical strikes across LoC
- Hafiz Saeed threatens Zee News, says Pak forces will teach what real surgical strikes are
- Pak postpones SAARC Summit after five member states pull out of conference: As it happened
- After threatening Zee News, Hafiz Saeed says PM Modi, Ajit Doval staged `surgical strike drama'
- India's surgical strikes: Pakistan buries slain terrorists to hide evidence, asks Masood Azhar to go mum
- Who is Chandu Babulal Chauhan and why India wants to bring him back from Pakistan - Read