The Antarctic water becomes salty and promotes the collapse of sea ice. Scientists don’t know why.
Antarctic sea ice has been declining since 2015, contrary to the model’s forecasts that it will reach a record 0.6 million square miles (1.55 million square kilometers) above the expected average range for 2023, in opposition to the model’s forecast.
This decline — the biggest environmental change seen anywhere on the planet in recent decades — will have ripple effects on the global climate.
You might like it
Now, scientists are linking decline to an unexpected, yet unexplained rise in the salty taste of the water surrounding the continent. The researchers published their findings in the PNAS Journal on June 30th.
“We were surprised. This is counterintuitive because we usually associate melted ice with ocean bluntness,” Alessandro Silvano, a senior scientist at the University of Southampton, told Live Science. “This indicates deeper structural changes in the South Seas, not just the sea ice, but also the oceans below.”
The problematic sea
The sea ice surrounding the Earth’s poles melts in summer and freezes in winter, fluctuating between minimum and maximum values. In Antarctica, the ice acts as a moat that protects the continent’s increasingly unstable land ice from warming seawater, bringing some of the solar energy back into space and traps carbon dioxide below the surface of the sea.
Related: “We couldn’t believe it”: Antarctica behaves in ways we’ve never seen before. Can I recover?
Since satellites began monitoring sea ice ranges in 1979, Arctic ice ranges have plummeted by more than 12% every decade. However, Antarctic ice continued to grow steadily, reaching its highest ever high in 2014. However, this trend deteriorated sharply in 2016, showing a fundamental change.
Scientists agree that the driver underlying this switch is climate change. However, sea ice forms at the boundary between the ocean and air, both of which are surprisingly complex systems. This predicts how complex warming mechanisms on ice can be difficult alongside remote southern oceans.
To investigate, the researchers behind the new research turned to the soil moisture and marine salinity satellites of the European Space Agency. This signal is messy and requires state-of-the-art algorithms to solve it. In other words, it has become possible to analyze it recently.
After examining daily measurements from 2011 to 2023, the researchers found that the decline in sea ice and the reopening of giant holes in its cover (such as Maud Rise Polynya from Weddell Sea) was consistent with a sharp increase in salt content. They were shocked by their results and doubted it until they were confirmed by data from the floating buoy.
Traditional wisdom suggests that as temperatures increase, melting ice from Antarctica ice shelves should increase freshwater content in the sea level. Instead, several unknown processes make the water saltier.
“The exact driver remains unknown,” Silvano said. “One possibility is that salt stored in deeper layers of the ocean has been lifted to the surface. This is a process that is potentially triggered by changes in ocean circulation or atmospheric forcing. We are actively investigating how and why this structural change began.”
Increased salinity leads to greater warming from surface water, which will help the ice melt faster. Because salt water is more dense than freshwater, the freshwater layer at the top of the water column acts as a lid, preventing warm water that normally circulates into the deeper layer from reaching the surface.
Sea ice is responsible for coming out of the coast where ice is formed and bringing freshwater from the coast. With freshwater lids broken, more warm water will rise, reducing the sea ice range and ensuring less freshwater in the future, Silvano said.
Other experts agree with the findings of the paper, describing it as a lack of puzzles that can explain the inconsistency between climate models and real-world data.
“The fact that this salinity change counters what is expected under climate change suggests that there are processes that we don’t fully understand and may not be included or well represented in climate models,” Arian Pulic, a climate researcher at Antarctic University at Monash University in Australia, told Live Science. Purich suggests that investigating the gap between model predictions and measures like these could provide new insights.
Caroline Holmes, a polar researcher at the British Antarctic Survey, says that it is “a type of observation that provides information to incorporate appropriate processes into the model.” “The subsurface south is not chronically monitored. At this point there is momentum towards two major initiatives, Antarctica and international polar.
Meanwhile, Silvano and his colleagues look at what caused the salt spikes in 2015 and whether this could be considered a turning point.
“The timeline for these changes to be widespread worldwide is uncertain, but if the current trend continues, there could be more significant effects within decades,” Silvano said. “Reduced sea ice could allow for the release of carbon stored in the South Seas, as it occurred during past warm climate periods.
Source link
