Researchers fear catastrophic side effects of global warming
Scientists are alarmed that sea ice in Antarctica remains at historic lows. In their opinion, the «shocking» shift is the beginning of global warming associated with the destruction of ice, which can have disturbing side effects.
Almost every morning, writes Guardian Australia, from late March until the time University of Tasmania sea ice specialist Will Hobbs can do anything other than make coffee, he's going through his inbox looking for one particular email.
This email, auto-generated and sent by a colleague, arrives just after 4am and contains the latest US government satellite data showing how much sea ice is floating around Antarctica.
“Unprecedented is a word that gets thrown around a lot, but it doesn't really capture how shocking it is,” says Hobbs. “This is very much beyond our understanding of this system.”
In February, the amount of floating sea ice around Antarctica hit an all-time low for the second year in a row. Since satellites began tracking the ice in the region in 1979, there has never been less ice here.
As it does every year, as temperatures on the continent approached winter, the sea ice began to return. But scientists' mild dismay at this record low, reached just a year after the previous record low, is now being overshadowed by surprise. Some are concerned that they may be witnessing the start of a slow melting of Antarctica's sea ice.
By now, there are typically about 16.4 million square kilometers of sea ice in Antarctica. But this week, its area was only 14.1 million square meters. km. An area larger than Mexico has not been frozen, Guardian Australia notes.
“There is a sense that something strange is going on. This is way below anything we've seen in our records,» says Dr. Walt Meyer, senior scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado.
Meyer's job is to help collect and present data from US satellites that have been recording sea ice since November 1978.
This is the same data that comes in Hobbs' daily email, and the same data that has been turned into graphs and shared on social media around the world in recent weeks.
Every day, an American satellite flies over the region with an instrument on board that — through the clouds and at night — can determine whether the surface of the ocean is covered with ice or water.
Every morning around 7 a.m. in Boulder, Colorado, an automated system collects data, runs an algorithm, and outputs the average amount of ice on the continent over the past five days, Guardian Australia continues.
“In terms of what it is relatively normal, we're even further behind where we were in February, Meyer says. “It's quite remarkable, and there are moments when we look at it and say, wow, that's weird.”
Not only is there less ice, but there is a reduction along almost the entire 18,000 km coastline of the continent.
While floating ice in the northern Arctic behaved as scientists and climate models expected in a warming world, apparently at its limits, Antarctica's sea ice remained stable.
But in In 2016, something turned upside down, writes Guardian Australia. Just two years after the all-time high, 2016 hit an all-time low and has seen a strong downward trend ever since. Scientists are still arguing why.
Much of the problem in understanding Antarctica's sea ice lies in its location. Surrounded on all sides by boundless ocean, sea ice is affected by winds, storms, air temperature, changes in ocean temperature, salinity, and how different layers of the ocean mix. It is not easy to identify all these influences and interactions in order to identify any impact of climate change.
Meyer says it's hard to tell whether these changes are natural or human-induced — or a combination of both — and notes that there is some evidence of a similar sudden jump from high to very low sea ice in satellite photographs from the mid-1960s.
Dr Andrew Meyers, an oceanographer with the British Antarctic Survey, says many climatologists who «were not necessarily sea ice lovers» suspect that the fall since 2016 has shown that climate change has «finally overcome the natural barriers around sea ice formed by unique wind and atmospheric circulation.” But there was a lack of concrete evidence to support this view.
“Overall, it feels like something big is happening this year, and this is likely due to the wider decline since 2016,” believes Dr Meyers. “Whether this is an anthropogenic cause, and if so what the driving force might be, is still a matter of debate.”
But there is at least one working theory to explain the loss of sea ice. The waters around Antarctica are strangely turned upside down. The upper layers of the ocean are stratified — a colder and less saline layer on top and a warmer and denser layer at a depth of about 150-300 meters.
Professor Alex Haumann, an oceanographer and sea ice expert at Ludwig Maximilian University in Munich, says there is evidence that just before the current downturn, the top layer became saltier and mixed with the bottom layer, allowing warmer water to reach the surface and make it harder to form. ice.
This may be due to natural weather conditions, but the expert emphasizes that it is inexplicable that the warm layer has become “significantly warmer” since the 1960s.
Professor Haumann, who has presented his theory to colleagues at several regional and international meetings, says that given his theory, the extraordinary falls this year were not unexpected. “People bet beer with me that this theory is wrong,” he says. “It's a safe bet for me.”
The loss of Antarctica's sea ice could have serious side effects — not just for krill, fish, penguins, seals and other animals. Melting sea ice does not in itself cause sea levels to rise because it is already buoyant. But Dr. Arian Puric, a climatologist at Monash University and an expert on the continent's sea ice, lists three reasons for concern.
The loss of ice means less solar energy is reflected back into space, causing more ocean warming. Antarctic sea ice also affects how the ocean circulates oxygen and nutrients around the globe.
But sea ice also protects land-attached ice by holding back waves, which is what many scientists believe the most disturbing.
“Without it, the waves break on the ice shelves and cause them to break off faster. Then the ice sheet could slide faster into the ocean, raising sea levels around the world, says Arian Puric. “I think everyone is asking what is happening right now. It's incredible. There is such an anxiety about what kind of world we will fall into. Given the evidence, I feel it would be irresponsible not to attribute this to global warming, to a warmer atmosphere and a warmer ocean.”
All scientists interviewed by Guardian Australia said there was an urgent need in more research and funding to help them find answers.
“I'm genuinely concerned,” admits Hobbs. “As a scientist, I'm worried that I can't find the answers or that we might be missing something. And it seems to me that the stakes are very high in getting it wrong. If — and this is a big «if» — this is a functional failure of the system, then this means that we need to revise our sea level forecasts, and this will affect many people. These are the stakes we play. As scientists, we have a real responsibility to make sure this doesn't get messed up.”