How to

24 April 2017

Warm Water Currents Threaten Arctic Sea Ice, Study Reveals

Driven primarily by atmospheric thermodynamic forcing, Arctic sea ice loss is a leading indicator of climate change, allowing us to easily visualise the extent of the damage done by human populations to our increasingly-delicate planet. However, new research has indicated that on top of such atmospheric forcing, an increase in the release of oceanic heat as a result of warm water currents invading the region is also having a comparable and detrimental effect on the Arctic.

In a study published earlier this month in the journal Science, researchers detailed how the eastern Eurasian Basin, located near Scandinavia and Russia, is changing as a result of these warm currents, becoming increasingly alike to the western Eurasian Basin and the Atlantic Ocean in its composition. This “atlantification” has resulted in disruptions within the water column, which in turn leads to warming surface waters.

The Arctic Ocean is different to the Atlantic and Pacific Oceans in that the coldest layer of water is situated at the surface, while the halocline layer – a thick band of cold, heavily-salinated water – keeps the cold surface waters separate from the warmer water found at depth. This Halocline layer has been weakening since the 1970s, allowing the layers to mix and leading to a warming of the basin.

In order to ascertain the scale of the problem, researchers opted to use oceanographic moorings and drifting Ice-Tethered Profiler buoys to collect data on subsurface ocean temperature ranges and salinity between 2013 and 2015. Their results are somewhat worrying, indicating that the difference in water temperatures between the layers has dropped by approximately 1°C since 2002. While that may not seem like much, any climatologist worth their salt will tell you it’s more than enough to cause widespread issues. Furthermore, the once-weakening halocline layer was found to disappear entirely in some months.

“In short, the basin used to be a three-layer cake, and now it’s a two-layer cake,” says Eddy Carmack, a co-author of the study. “It’s quite remarkable that you’d see the architecture of the Arctic Ocean change just within a decade. It’s the kind of thing you’d expect over a 100-year time frame.”

Largely as a result of the deterioration of the halocline layer and the subsequently warmer waters, the eastern Eurasian Basin has been nearly ice-free towards the end of each summer since 2011. Whilst this was once attributed to a combination of warming air temperatures and the increased ability of an ice-free oceanic region to absorb heat, this new research has led oceanographers to hypothesise that this influx of warm currents is also playing a significant role in the process. Researchers are now worried that this trend may continue, leading to the “atlantification” of other parts of the Arctic Ocean, such as the Barents Sea.

“The processes in the Barents and Norwegian seas, the upstream locations for the Eurasian Basin, show the same tendencies as in the last decade,” says Igor Polyakov, lead author of the study. “We may expect that the atlantification of the eastern Eurasian Basin will continue, but whether it will go further eastward is yet to be seen.”

The research article abstract concludes by stating that “this encroaching ‘atlantification’ of the Eurasian Basin represents an essential step toward a new Arctic climate state, with a substantially greater role for Atlantic inflows.”

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.