The First Ice-Free Day in the Arctic Ocean Could Occur Before 2030, Says Researchers
Ice floes in the Arctic Ocean on the west side of Greenland (Source: Courtesy of Christian Hoiberg on Flickr.com under CC BY-NC-ND 2.0)
Researchers have now given the first projections of when the first ice-free September day in the Arctic Ocean could occur. Based on simulations, researchers say that the first ice-free day could occur before 2030.
Céline Heuzé (University of Gothenburg) and Alexandra Jahn (University of Colorado Boulder) recently published an article in Nature Communications stating that the first ice-free September day in the Arctic Ocean could occur before 2030.
The researchers have utilized simulations to give these projections, but highlight that there is a large range of the projected first ice-free day. While some say the first ice-free day could occur before 2030, others say it won't happen before the end of simulations in 2100, depending on the model and forcing scenario used.
They investigated nine simulations in which the first ice-free day occurred within 3-6 years to determine what could have caused such a scenario.
Scenarios
An ice-free day is defined as a day with less than 1 million square kilometers of ice.
The models found that rapid sea ice loss comes from a combination of natural events and warming. Warm winters and springs entail less cold weather, which leads to thinner ice and a slower formation of new ice.
Stormy summers would also be one of the final triggers before the first ice-free day by breaking up ice and pushing it around, causing it to melt faster.
The two researchers state that natural variability in climate systems plays a vital role in determining the timing of the first ice-free day, often even overshadowing the influence of emissions in various scenarios.
Even with low emissions, rapid sea ice loss events can occur due to climate variability, such as the El Niño climate pattern.
Significance
An ice-free day would be a major climate milestone, showing how much human activities have warmed the planet.
The first ice-free day is followed by a gradual increase in ice-free days per year, says the researchers, adding that this transition can span decades.
The first ice-free day will represent a dramatic change in the Arctic ecosystem, and animals such as polar bears and fish can suffer significant losses.
The 1.5°C target
The researchers highlight that this development can be slowed down, but only if global warming is kept below 1.5°C (the target of the Paris Agreement).
Yet, they underline that this "may not prevent an internal-variability induced first ice-free day but could increase the probability of delaying or avoiding an ice-free day and month."
However, lower emissions reduce the chance of an ice-free Arctic. The researchers found that the primary trigger of the rapid transition to the first ice-free day within 3-6 years was a warm atmosphere in the previous winter and spring.
In all the scenarios studied, the first ice-free day happens only when global temperatures have warmed by 1.5°C or more above pre-industrial levels.
Thus, ice-free days could potentially still be avoided.
