Over the past century, most of the Earth’s land and ocean surfaces have been warming steadily, and we now know it’s a product of climate change,media New Atlas reported. But since the early 1980s, the sea has cooled sharply in parts of the Southern Ocean near Antarctica. Now, scientists think they already know why.
Human influence on the earth has been around for thousands of years, but during the Industrial Revolution, we really brought things to a climax. Since the 1830s, carbon dioxide emissions have been rising, leading to a series of environmental problems. Most notably, the continued warming of land and sea. The last few months, years and decades have been the hottest on record, with global land temperatures estimated to be 1.1C (1.98F) above the 20th century average in 2019. Meanwhile, the average ocean temperature has reached its highest level on record recent lying.
But not all areas of the ocean are warming. Between 1982 and 2011, there was a fairly noticeable cooling in parts of the Southern Ocean. This effect is most pronounced in the Pacific, where surface water temperatures fall by about 0.1 degrees Celsius (0.18 degrees F) per decade. Other parts of the Southern Ocean, such as the Indian Ocean and Atlantic plates, have a weak cooling effect, but are still evident.
Scientists have been unable to figure out why the region is bucking global warming. But now a team of researchers at the Federal Institute of Technology in Zurich has come up with a model to explain this. At the beginning of the study, scientists observed an increase in sea ice cover in the waters off Antarctica over the same period of 30 years. At the same time, at the other end of the globe, the extent of sea ice continues to shrink.
A few years ago, scientists figured out why southern sea ice expanded so much, with stronger winds pushing more sea ice off the Antarctic continent, where more sea ice was formed. According to the new study, this may be the reason. Using detailed computer simulations of ocean mechanisms, the researchers found that when they included melting sea ice, they were able to produce colder seawater. Other factors, such as stronger ocean circulation patterns or more fresh water flowing out of Antarctic glaciers, do not explain these observations.
Sea ice is a problem because when it melts, it releases fresh water into the ocean. This reduces the salinity of the sea, which tends to float over higher density salinity. Like oil floating on the surface, these layers cannot be mixed together as normal, causing hotter waters to be trapped in deeper places while the sea becomes colder.
“The cooling of the Southern Ocean over the past three decades is really unusual, and you know that all other parts of the planet, especially the land surface, are warming,” said Lead researcher Nicolas Gruber of the study. “We assume that strong winds pushing sea ice northwards in the Southern Ocean may be a side effect of climate change. Climate change is clearly man-made and cannot be called into question because there are signs of cooling in an area of the ocean. “
“We have observed a trend reversal since 2015. The sea ice around Antarctica is now beginning to recede rapidly. Gruber said. “This is very much in line with the general trend of continued global warming. “
The study was published in the journal AGU Advances.