On the Arctic Ocean rests a blanket of sea ice. But this sea ice has been subject to change for some time. As temperatures rise, more and more sea ice is melting. And not slowly and steadily, but at breakneck speed.
Until now, climate models predicted that Arctic temperatures would gradually rise. But a new study now shows that these changes are happening much faster than expected. “We looked at the climate models that have been analyzed and assessed by the UN climate panel,” said researcher Jens Hesselbjerg Christensen. And from that, a disturbing conclusion rolls. “Only the models based on the worst-case scenario (i.e. with the highest carbon dioxide emissions) come close to what our temperature measurements of the past 40 years show.”
Over the past forty years (i.e. from 1979 to the present) temperatures have increased by one degree every decade. The mercury rose even faster over the Barents Sea and around Norway’s Svalbard archipelago. Over the same period, researchers saw the temperature here rise by 1.5 degrees per decade. “Our analyses of conditions in the Arctic Ocean show that we have clearly underestimated the rate of temperature increases,” said Hesselbjerg Christensen. It means that temperatures in the Arctic Ocean between Canada, Russia and Europe are higher than the climate models have shown.
In the study, the researchers compared current temperature changes in the Arctic with climate fluctuations from Greenland, among others, during the ice age that occurred between 120,000 – 11,000 years ago. And the findings are worrisome. “The abrupt rise in temperature that we are experiencing in the Arctic today, we have only seen during the last ice age,” says Hesselbjerg Christensen. “Analyses of ice cores have shown that the temperature above the Greenland ice sheet has risen several times by 10 to 12 degrees Celsius over a period of 40 to 100 years.” The researcher stresses the seriousness of the situation. A greater focus on the Arctic and tackling global warming in general is therefore necessary.
The rapid rise in temperature, as mentioned, mainly has an impact on melting Arctic sea ice. Because the temperature rises in emergency mode, much more sea ice is melting than expected. This trend has actually been going on since the 1950s. Where there was first mainly thick, multi-year ice on the sea, thinner, seasonal ice sheets now take the upper hand. And that’s kind of worrisome. For example, multi-year ice is thicker, stronger and coarser than seasonal ice. In addition, it is less salty – for example, it can serve as drinking water. Thinner ice is obviously weaker. It melts faster and breaks down more easily. This makes it much more susceptible to, for example, the wind.
According to the researchers, more attention should be paid to accurately simulate the impact of abrupt climate change on the Arctic. Because then we can also develop better models that predict the temperature increases more accurately. “The changes are so rapid during the summer months that sea ice disappears much faster than most climate models have ever predicted,” says Hesselbjerg Christensen. “We need to keep a close eye on temperature changes and incorporate the right climate processes into these models.”
According to the researchers, it is important to strive for the objectives of the Paris Climate Agreement. Under the agreement, countries pledge to limit global warming to 2 and, if possible, as much as 1.5 degrees Celsius. This would limit the effects of climate change – melting sea ice, melting ice sheets, higher sea levels, more extreme weather, etc. “Successfully implementing the necessary reductions in greenhouse gas emissions is essential to ensure year-round sea ice in the Arctic,” said Hesselbjerg Christensen. It is questionable however whether this is still feasible. Indeed, several studies have shown that it is increasingly likely that the Arctic will be ice-free in a few decades during the summer. Even if we do our utmost to keep global warming below two degrees Celsius.