Patchy: Arctic ice cannot form properly under global warming conditions,
with knock-on effects worldwide. Photo: Polar Bears International/AFP
New satellite data has shown how the intrusion of warmer Atlantic waters is reducing ice regrowth in the Arctic Ocean in the winter via a process that has been dubbed “Atlantification”.
The amount of sea ice floating in the Arctic Ocean varies enormously as it grows and shrinks with the seasons, according to the European Space Agency (ESA).
“Although some of the older, thicker ice remains throughout, there is an undeniable trend of declining ice as climate change tightens its grip on this fragile polar region,” the ESA has found.
Arctic sea ice reaches its maximum volumes around March, after the cold winter months, and then shrinks to a minimum around September, after the summer melt.
“However, these seasonal swings are not only linked to the changing seasons — it transpires that along with our warming climate, the temperature of adjacent ocean sea water is now also adding to the ice’s vulnerability,” according to the agency.
While previous research suggested that sea ice can partly recover in the winter following a strong summer melt as thin ice grows faster than thick ice, new research published in the Journal of Climate showed that heat from the ocean is “overpowering this stabilising effect, reducing the volume of sea ice that can regrow in the winter”.
This means that sea ice is more vulnerable during warmer summers and winter storms.
The researchers used satellite data from the agency’s climate change initiative to calculate changes in the volume of Arctic sea ice between 2002 and 2019. “The Arctic is one of the hotspots of drastic changes in the earth’s climate system, a result of global warming associated with rising air temperatures,” the authors note. These changes are accompanied by significant declining rates in sea ice concentration and thickness during recent decades.
“With continuing Atlantification and rising winter air temperatures, record lows in winter sea ice extent will very likely continue to occur in the upcoming years,” they warn.
Environmental futurist professor Nick King says the Atlantification of the Arctic Ocean is a very important, complex issue.
“What we know is that the annual seasonal warming and cooling of the poles is an integral driver of our planetary weather system, so any mega-changes there impact everywhere,” he told the Mail & Guardian.
“We have seen some small examples of this already, for example, the change in the jet stream and the mega and unseasonal storms this has produced over Europe and North America.”
Apart from weather, the lack of Arctic sea ice also means changes to ocean currents and potentially the weakening or even cessation of one or more of the major global ocean circulation systems.
King cites as an example the Atlantic meridional overturning circulation current — the warm gulf stream that largely makes northwest Europe habitable and “which, if it ceased to flow, would change almost everything about the oceans and habitable lands that we know”.
These changes in water temperatures and currents “and, of course, ocean acidification, also from burning fossil fuels” are already affecting marine life and would likely cause collapse of ocean ecosystems as nutrient production changes, having cascading effects on trophic systems (the way food webs interact with each other).
“This will likely collapse ocean ecology and associated economic activity everywhere,” King explains.
[/membership]