As a result of global warming, the sea ice around the North Pole is slowly melting away: the current ice surface is about 40 percent smaller in summer than 40 years ago. If this warming continues, an ice-free North Pole will become inevitable. But when? British researchers think that it will already be in fifteen years.
A research team from the University of Reading used a fine-mesh climate model that allowed it to simulate a relatively warm period prior to the last Ice Age. During this period, at least, the Arctic Ocean was completely ice-free in summer.
Although it was slightly warmer at the height of that period than it is now, that cannot explain the complete melting of the polar ice. There must have been reinforcing factors that accelerated the loss of ice. And one of those factors could play a role in the current warming, the British write in Nature Climate Change : melt water pools.
Warming creates pools that amplify warming
Due to the current warming, puddles of meltwater are also increasingly forming, both on thick ice sheets such as Greenland and Antarctica, as well as on the floating sea ice of the Arctic. Because this meltwater absorbs much more solar heat than the underlying ice, the pools amplify local warming.
This is also evident from temperature reconstructions. On average, it was 1.5 degrees warmer at the peak of the current climate. However, the Arctic was no less than 4 to 5 degrees warmer in summer, suggesting that more solar heat was being absorbed at the time.
Is this factor indeed strong enough to have an ice-free North Pole by 2035? NU.nl asked a Dutch expert: polar researcher Richard Bintanja of the KNMI and the University of Groningen.
"Those meltwater pools are certainly an important factor accelerating ice loss," says Bintanja. "But there are more such melt-accelerating factors. For example, rain falls more and more often at the North Pole. As a result, the snow layer on the ice is quickly affected, while the white snow layer has a protective effect against meltdown."
See also: Melting Ice in the News: Is Climate Change Accelerating?
Ice volume decreases faster than surface area
According to Bintanja, the current decline in sea ice is also difficult to read from the decreasing ice surface. Although it is slowly getting smaller, the thickness of the remaining ice is also decreasing further and further. If that decreasing thickness is also taken into account, the total ice volume appears to have already shrunk by three quarters in the past forty years - a line that thus ends at a much faster rate at an ice-free North Pole.
With regard to the prediction of an ice-free North Pole around 2035, Bintanja does not hesitate. "It depends on many things, such as, of course, the further increase in the CO2 concentration and the temperature."
"But the trickiest factor is that climate change will not only increase the average temperature in the area, but also change the climate variability. The first ice-free summer will coincide with an extremely warm year in the area. And as we know from our own. heat waves: you cannot predict exactly in advance in which year such records will be broken. "
"My personal estimate for the first largely ice-free Arctic summer is between 2040 and 2045. But that we are moving towards that is now certain."
See also: Arctic ice rapidly deteriorating: Almost three quarters have disappeared in 40 years