'Dramatic decline': Calgary researcher says sea ice in Antarctica lowest since 1986
CBC
Sat, October 21, 2023
A Calgary researcher, who has spent the last eight months in Antarctica studying sea ice, says he has seen first-hand how big an effect climate change has had in the region.
Vishnu Nandan, a post-doctoral associate with the University of Calgary, along with Robbie Mallett, from the University of Manitoba, have been studying ways to improve how radar satellites measure the thickness of Antarctic sea ice and snow.
The research is part of a British-based project called DEFIANT — Drivers and Effects of Fluctuations in sea Ice in the ANTarctic — which aims to deploy a state-of-the-art ground-based radar system that mimics the satellites in space.
"We actually came knowing we wouldn't have a lot of sea ice, because it's been really warm," Nandan said in a phone interview from Rothera Research Station on Adelaide Island, nearly 1,900 kilometres south of the Falkland Islands.
"We came in where we had the lowest sea ice on record over the past many decades, so we didn't have sea ice much and we had really thin ice in the winter."
Accurate readings difficult
Nandan said the issue is that the area gets so much snow, sometimes up to a metre, that it's difficult to get accurate satellite readings of snow and sea ice thickness.
They've been collecting data from the ground-based radar system to account for errors and correct satellite algorithms to produce accurate measurements critical for climate change projections.
Nandan did similar research a few years ago in the central Arctic Ocean, when he was on an icebreaker for a year in an extended examination of global warming from a vantage point close to the North Pole.
"Arctic sea ice has declined substantially — about 70 per cent over the past 30 to 40 years. When compared to that, the Antarctic has been stable, but over the past few years, since about 2016, we have seen a dramatic decline in sea ice in many regions across the Antarctic," Nandan said.
"Right now it's serious. It's really bad. If you look at the overall area of the sea ice, the area is almost one million square kilometres less than the previous lowest, which was in 1986."
Although there has still been lots of snow, there were several days of rain, which is unusual, said Nandan. He added that the warm wind is preventing the ocean ice from freezing solidly.
Loss of ice makes oceans warmer
He said his research, which is also supported by the University of Manitoba, is important considering what can happen with declining sea ice.
"Sea ice is white in colour and reflects most of the sunlight that is hitting it," he said. "If you don't have enough sea ice, that means there's a lot of open ocean, which is actually absorbing most of the sunlight."
In turn, Nandan said that makes the polar oceans warmer, which can affect both the ecosystem and the weather.
"You get more climate disasters like tornadoes, cyclones, extreme weather events like cloudbursts," he said.
"It affects the ecosystem, from polar bears, phytoplanktons, to animals like seals who need sea ice for their habitat."
Nandan has completed his stint in the Antarctic and will be returning to Calgary next month.
Humans may have lost control of West Antarctic Ice Shelf melting, study finds
Danny Halpin, PA Environment Correspondent
Mon, 23 October 2023
Humans “may have lost control” of the West Antarctic Ice Sheet – with inevitable melting from heating caused by greenhouse gas emissions set to raise sea levels throughout the following decades, a study has found.
Even if emissions are controlled to achieve the best possible scenario, melting of the ice sheet will continue to accelerate this century, at a speed three times faster than during the 20th century.
Warming oceans, that are absorbing excess heat from the atmosphere, erode the ice sheet from underneath and this effect is most pronounced on the western side of the continent.
Scientists are unsure how much this is likely to contribute towards global sea level rise but if the entire West Antarctic Ice Sheet melted it would contribute around five metres, though this scenario is seen as unlikely to happen.
East Antarctica, which contains around 95% of the continent’s ice, remains stable as far as scientists can see, with a recent study finding the amount of ice has been increasing there over the past 30 years, though it is rapidly melting in the west with a net loss of around 7.5 trillion tonnes of ice.
How much this melting will contribute to rising oceans is not as well understood as other polar regions such as the Greenland glaciers.
Dr Kaitlin Naughten of the British Antarctic Survey (BAS) and lead author of the study said other research beyond her own points to it contributing to around one metre of sea level rise by 2100.
Describing her findings, she said: “It appears we may have lost control of the West Antarctic Ice Shelf melting over the 21st century.
“Our actions today likely will make a difference further down the line in the 22nd century and beyond, but that’s a timescale that probably none of us here will be around to see.”
The research, published in the journal Nature Climate Change, has been described by scientists as “sobering” as it points to an inevitable rising of sea levels that will likely devastate many coastal communities if they do not adapt.
The ocean temperature around West Antarctica will continue warming even under the best case scenario (Kaitlin Naughten et al/Nature Climate Change/PA)
Already in the UK the Welsh village of Fairbourne is scheduled for abandonment in the 2050s by Gwynedd Council after it announced it will no longer keep up sea defences.
Millions of people around the world live by the coast and will either have to “build around” the threat or “be abandoned”, Dr Naughten said, who added that controlling emissions would result in slower sea level rise which would give people more time to adapt.
For the current study, Dr Naughten’s BAS team simulated four scenarios for the current century against a historic baseline of the previous one, imagining that emissions are either controlled to rein in the global temperature rise to 1.5C or 2C above pre-industrial levels or that emissions continue at a medium or high level.
Every scenario showed there would be widespread warming of the Amundsen sea, which borders West Antarctica, resulting in faster melting of the ice sheets.
The various emissions pathways did not show much difference until around 2045, when the high-emissions simulation began to increase the rate of melting faster than the other scenarios.
Other scientists cautioned against viewing the results of the study as being absolutely conclusive as they are based on a single model, but that it is in line with other similar studies.
Professor Alberto Naveira Garabato, an oceanographer at the University of Southampton, said: “This is a sobering piece of research.
“It illustrates how our past choices have likely committed us to substantial melting of the West Antarctic Ice Sheet and its consequent sea level rise – to which we will inevitably have to adapt as a society over coming decades and centuries.
“However, it should also serve as a wake up call. We can still save the rest of the Antarctic Ice Sheet, containing about 10 times as many metres of sea level rise, if we learn from our past inaction and start reducing greenhouse gas emissions now.”
Danny Halpin, PA Environment Correspondent
Mon, 23 October 2023
Humans “may have lost control” of the West Antarctic Ice Sheet – with inevitable melting from heating caused by greenhouse gas emissions set to raise sea levels throughout the following decades, a study has found.
Even if emissions are controlled to achieve the best possible scenario, melting of the ice sheet will continue to accelerate this century, at a speed three times faster than during the 20th century.
Warming oceans, that are absorbing excess heat from the atmosphere, erode the ice sheet from underneath and this effect is most pronounced on the western side of the continent.
Scientists are unsure how much this is likely to contribute towards global sea level rise but if the entire West Antarctic Ice Sheet melted it would contribute around five metres, though this scenario is seen as unlikely to happen.
East Antarctica, which contains around 95% of the continent’s ice, remains stable as far as scientists can see, with a recent study finding the amount of ice has been increasing there over the past 30 years, though it is rapidly melting in the west with a net loss of around 7.5 trillion tonnes of ice.
How much this melting will contribute to rising oceans is not as well understood as other polar regions such as the Greenland glaciers.
Dr Kaitlin Naughten of the British Antarctic Survey (BAS) and lead author of the study said other research beyond her own points to it contributing to around one metre of sea level rise by 2100.
Describing her findings, she said: “It appears we may have lost control of the West Antarctic Ice Shelf melting over the 21st century.
“Our actions today likely will make a difference further down the line in the 22nd century and beyond, but that’s a timescale that probably none of us here will be around to see.”
The research, published in the journal Nature Climate Change, has been described by scientists as “sobering” as it points to an inevitable rising of sea levels that will likely devastate many coastal communities if they do not adapt.
The ocean temperature around West Antarctica will continue warming even under the best case scenario (Kaitlin Naughten et al/Nature Climate Change/PA)
Already in the UK the Welsh village of Fairbourne is scheduled for abandonment in the 2050s by Gwynedd Council after it announced it will no longer keep up sea defences.
Millions of people around the world live by the coast and will either have to “build around” the threat or “be abandoned”, Dr Naughten said, who added that controlling emissions would result in slower sea level rise which would give people more time to adapt.
For the current study, Dr Naughten’s BAS team simulated four scenarios for the current century against a historic baseline of the previous one, imagining that emissions are either controlled to rein in the global temperature rise to 1.5C or 2C above pre-industrial levels or that emissions continue at a medium or high level.
Every scenario showed there would be widespread warming of the Amundsen sea, which borders West Antarctica, resulting in faster melting of the ice sheets.
The various emissions pathways did not show much difference until around 2045, when the high-emissions simulation began to increase the rate of melting faster than the other scenarios.
Other scientists cautioned against viewing the results of the study as being absolutely conclusive as they are based on a single model, but that it is in line with other similar studies.
Professor Alberto Naveira Garabato, an oceanographer at the University of Southampton, said: “This is a sobering piece of research.
“It illustrates how our past choices have likely committed us to substantial melting of the West Antarctic Ice Sheet and its consequent sea level rise – to which we will inevitably have to adapt as a society over coming decades and centuries.
“However, it should also serve as a wake up call. We can still save the rest of the Antarctic Ice Sheet, containing about 10 times as many metres of sea level rise, if we learn from our past inaction and start reducing greenhouse gas emissions now.”
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