the cover of sea ice of Arctic it is declining throughout every month since the early 1950s, and moreover, it is almost halved during the summer time. The amount of sea ice surviving the arctic summer has decreased by 13% per decade since the late 1970s and projections show that the region could experience its first ice-free summer by 2040.
This rapid melting is not only detrimental to surrounding coastal cities and small island nations; it may also have a lasting impact on global weather patterns, according to research published in the journal Nature Communications and that has been carried out by a team of scientists from the University of Albany (New York, USA).
In that document, scientists reveal that the magnitude and pattern of sea ice loss in the Arctic can directly influence the climatic phenomenon known as El Niño. Also, As the Arctic loses seasonal ice, the frequency of strong El Niño events increases significantly, namely by more than a third.
The El Niño current is a complex weather pattern which occurs when surface water in the central and eastern Pacific Ocean becomes warmer than average and easterly winds blow weaker than normal. These episodes, which usually occur every few years, can lead to unusual weather conditions and sometimes, dangerous around the world, including droughts, floods and severe storms.
“Prior to this study, little was known about whether decrease of Arctic sea ice is capable of influencing strong El Niño events,” said its lead author, Jiping Liu, associate professor in the Department of Atmospheric and Environmental Sciences in the Albany College of Arts and Sciences.
He added: “El Niño is an important climatic phenomenon, recognized as a driver of climate variability responsible for large and diverse social impacts. Our study, for the first time, demonstrates that the large loss of Arctic sea ice directly influences global climate extremes, including an increase in the frequency of strong El Niño events.”
With less ice, El Niño will be more intense
Liu and his colleagues ran a series of simulations of time interval models which relied on variables from the atmosphere, land, ocean, and sea ice to determine the influence of Arctic sea ice loss on El Niño events. Before running the simulations, they set the Arctic sea ice cover for three periods: 1980–99, 2020–2039, and 2080–99.
Simulations were generated using the National Center for Atmospheric Research Community Climate System Model, a global climate model that provides state-of-the-art computer simulations of Earth’s past, present, and future climate states.
Comparing the results, the researchers found no significant changes in the occurrence of strong events of El Niño in response to moderate sea ice loss in the Arctic, which is consistent with satellite observations to date. However, as ice loss continues and the Arctic becomes seasonally ice-free, the frequency of strong El Niño events increases by more than a third.
“After decades of research, there is general, though not universal, agreement that the frequency of El Niño events, especially extremely strong events, will increase with warming from the greenhouse effect Liu stated. Given that Arctic sea ice is projected to continue to decline dramatically, it was important to assess whether the projected increase in a strong El Niño can be directly connected.”
To separate the role of Arctic sea ice loss and greenhouse gas emissions, the researchers conducted an additional experiment in which the Arctic sea ice cover was fixed based on historical simulations, but carbon dioxide levels increased by 1% over 100 years from their level in the year 2000.
Thus, the experts concluded that between 37 and 48% of the increase in strong El Niño events near the end of the 21st century would be associated specifically with the loss of Arctic sea ice. “It is becoming increasingly clear that climate models need to realistically simulate Arctic sea ice decline to correctly size El Niño variability,” Liu concluded.