WHITE TO BLUE: ARCTIC OCEAN COULD SEE DAY WITHOUT ICE WITHIN NEXT FEW YEARS
▶ Melting ‘inevitable’ under all emissions scenarios as research predicts bleak future for animals such as polar bears
Sea ice could disappear during some summer days in the Arctic within the next few years, researchers have warned.
A study by scientists at the University of Colorado Boulder suggests the first ice-free day in the Arctic Ocean could occur more than 10 years earlier than previously thought.
Greenhouse gas emissions are the main contributors to sea ice loss, which increases the amount of heat from sunlight absorbed by the ocean, exacerbating ice melt and warming in the Arctic.
Analysing sea ice coverage data from climate models to predict how it may change in the future, the researchers said that an ice-free Arctic was “inevitable”.
The team predicts the Arctic Ocean could be free of ice for the first time on a late August or early September day, when levels are traditionally at a minimum, sometime in the 2020s or 2030s under all greenhouse gas emissions scenarios.
On the current path, which researchers refer to as an “intermediate emissions scenario”, the Arctic Ocean might become ice free from August to October by the middle of the century.
But in the worst-case scenario with the highest emissions, the Arctic, which is warming more than twice as fast as the rest of the planet, could become ice free nine months a year.
“This would transform the Arctic into a completely different environment, from a white summer Arctic to a blue Arctic,” said Alexandra Jahn, associate professor of atmospheric and oceanic sciences and fellow at CU Boulder’s Institute of Arctic and Alpine Research.
“So even if ice-free conditions are unavoidable, we still need to keep our emissions as low as possible to avoid prolonged ice-free conditions.”
An Arctic Ocean with less than one million square kilometres coverage would be considered ice free.
That is less than 20 per cent of the region’s seasonal minimum ice cover in the 1980s.
It is also significantly less than in recent years, when the Arctic Ocean had about 3.3 million square kilometres
of sea ice at its minimum in September.
Prof Jahn and her team found that the first day when sea ice coverage dips below the one-square-kilometre threshold would occur on average four years earlier than the monthly averages. But it could occur up to 18 years earlier.
“When it comes to communicating what scientists expect to happen in the Arctic, it is important to predict when we might observe the first ice-free conditions in the Arctic, which will show up in the daily satellite
data,” Prof Jahn said. Sea ice declines have significant impacts on Arctic animals that rely on it for survival, including seals and polar bears.
As the ocean warms up, researchers
are concerned that non-native fish could move into the Arctic Ocean.
The impact of these invasive species on local ecosystems remains unclear.
Sea ice loss also poses a risk to the communities living near the coastal region.
It plays a significant role in buffering the impacts of ocean waves on the coastal land, Prof Jahn said.
As sea ice retreats, ocean waves would get bigger, causing coastal erosion.
While an ice-free Arctic is
inevitable, Prof Jahn said future emissions levels will still determine how often the conditions occur.
The researchers stress that the Arctic sea ice is resilient and can return quickly if the atmosphere cools down.
“Unlike the ice sheet in Greenland that took thousands of years to build, even if we melt all the Arctic sea ice, if we can then figure out how to take C02 back out of the atmosphere in the future to reverse warming, sea ice will come back within a decade,” she said. Nasa’s
National Snow and Ice Data Centre warned that the average monthly Arctic sea ice last month was the 15th lowest in the satellite record, with temperatures above average but still well below freezing.
“Arctic sea ice extent in February tracked near the lowest decile of 10 per cent for much of the month,” it said.
“Based on the linear trend, February has lost 1.84 million square kilometres of ice since 1979.
“This is equivalent to the size of Alaska.”
On the current path the Arctic Ocean might become ice free from August to October by the middle of the century