Scientists do not doubt that climate change is bringing catastrophic changes to Antarctica. Surprisingly, however, researchers did not have enough ocean data to make a firm verdict on certain warming trends. Well, the data they needed has just hit the tables and the signals are clearer than ever.
A warm mass of circumpolar deep water continues to inch closer to the Antarctic ice shelves, according to a 20-year study of ocean measurements. This change in deep ocean heat was shown in climate model predictions, but the latest findings, published today in Earth and Environment CommunicationsThey provide empirical confirmation that warm water from the deep ocean is approaching the Antarctic ice shelves.
“This is not just a possible future scenario suggested by the models,” Joshua Lanham, lead author of the study and an earth scientist at the University of Cambridge in the United Kingdom, said in a statement. statement. “It’s something that’s happening now, which has broader implications for how carbon, nutrients and heat circulate through the global ocean.”
Our natural regulators
Deep ocean currents play a vital role in regulating Earth’s climate system, as well as ocean nutrient and carbon dioxide cycles, according to the US National Oceanic and Atmospheric Administration. These currents are driven by differences in water density caused by variations in temperature and salinity.
Around the poles, extremely cold temperatures cause dense, icy water to sink deep underwater, bringing with it heat, carbon and nutrients. This process is also essential for the Atlantic meridional circulation, which redistributes heat from the tropics to the Arctic, regulating the Earth’s climate.
Circumpolar deep water (CDW), on the other hand, refers to the water mass formed by the mixing of different water masses in the Pacific and Indian Oceans. Circumpolar deep water can warm up to 32 degrees Fahrenheit (0 degrees Celsius) near the Antarctic shelf rift, making it a major source of ocean heat in the region, the researchers explained in the paper.
Sinister changes
The latest findings present alarming evidence of increasing CDW volume near Antarctica “at almost all longitudes,” the study noted. For the analysis, the team combined measurements collected by argo fleet—small robotic floating devices launched en masse in the Southern Ocean—with public data from other autonomous floats on top of the ocean.
The researchers then used machine learning to consolidate this data with long-term patterns collected by research expeditions. The team offers some possible reasons for this expansion, such as unidentified changes in other water masses or strengthening westerly winds around the Southern Ocean. Confirming this will require further research, the researchers said in the study.
The terrible hot bath
In any case, we now have more evidence that Antarctica is in trouble. According to Sarah Purkey, lead author of the study and an oceanographer at the Scripps Institution of Oceanography, the Southern Ocean absorbs most of the anthropogenic heat stored in the ocean, which contains more than 90% of the excess heat created by global warming.
“In the past, ice sheets were protected by a cold water bath, preventing them from melting,” Purkey said. “Now it seems like the circulation of the ocean has changed, and it’s almost like someone turned on the hot water tap and now the bathroom is getting hot.”
If this unwanted “hot bath” persists and the ice shelves melt, the consequences are not great. Antarctica’s ice shelves keep the region’s ice sheets and glaciers intact, containing enough fresh water to raise the global mean sea level by 190 feet (58 meters), according to POT. Of particular concern, the study concluded, is how the expansion of CDWs will affect the Antarctic Circumpolar Currentan irreplaceable part of the Earth’s natural carbon sink.
Normally, when a study ends like this, it is usually the case that we will have to wait for independent verification or other natural developments to confirm something. But with everything at stake, waiting patiently might be the worst option.
