Iceland’s glaciers have lost about four billion tonnes of ice on average for the past 130 years. They’re the planet’s fastest-shrinking glaciers outside the polar ice caps, and about half the loss of volume has occurred in the past 25 years, according to a new article published in Frontiers in Earth Science.
Scientists from the University of Iceland’s Institute of Earth Sciences, the Icelandic Meteorological Office, National Land Survey of Iceland, and the National Power Company of Iceland have collected measurements and research of Icelandic glaciers for the past decades and published an article in Frontiers in Earth Science. They trace the glaciers’ development from their largest at the end of the 19th century to now. In total, the glaciers have lost between 410-670 billion tonnes of ice from 1890-2019. The glaciers receded quickly during the first part of the 20. century but natural climate pattern fluctuations slowed their recession from the sixties to the nineties. Since then, they’ve receded quicker than before due to global warming.
About half of the ice mass loss happened from autumn 1994 to the autumn of 2019, about 220-260 billion tonnes of ice, which amounts to about 10 billion tonnes per year. The glaciers have lost close to 16% of their volume in this period. “So we’re seeing swift changes now, due to climate change. Since 1995, all the glaciers have had a negative mass-balance and have been shrinking,” Guðfinna Th. Aðalgeirsdóttir, professor of geophysics the University of Iceland and the article’s primary author, told Vísir.
The research is based on size, volume, and glacier surface measurements gathered over the past decades. Based on that data, scientists extrapolated the likely development of glaciers in the preceding decades. The result of the research is that on average, Icelandic glaciers shrink faster than most glacial areas in the world, outside of the polar ice caps.
According to Guðfinna, glaciers melting is one of the most evident results of global warming in the world. Even if people managed to contain their emission of greenhouse gasses and prevent further global warming, glaciers would continue to melt for decades while they acclimatised to the new conditions.
Global warming is not the only factor in Icelandic glaciers melting. Scientists found that Vatnajökull glacier lost 3.7 billion tonnes of ice during the Gjálp volcanic eruption in October 1996 and over the summer of 2010, twice the usual amount of ice melted due to the Eyjafjallajökull eruption. Geothermal activity, glacial lagoon calving, and ice cap friction with bedrock also added to the loss of ice mass.
Individual glaciers have gotten thinner by dozens of metres in the last century. Vatnajökull has lost 45 meters, Langjökull 66 metres, and Höfsjökull 56 metres for the past 130 years. During that time, Vatnajökull has lost 12% of its volume, Langjökull 29% and Höfsjökull 25%.
The glaciers don’t shrink linearly, and their volume fluctuates every year. Despite an overall recession in the past decades, glaciers gained mass in the winter of 2014-2015. That winter saw several low-pressure systems arriving one after the other, bringing large amounts of precipitation and was followed by a relatively cool summer. That was the last time Iceland’s glaciers gained mass over winter and the only such winter for the past 25 years.
Guðfinna told Vísir this trend could continue and even grow clearer on a planet that’s heating up. “we see the weather extremes grow bigger each year due to climate change and that increases the yearly variation in the glaciers.”
The science committee of the Icelandic Science and Technology Council’s 2018 report on how climate change would affect Iceland forecasted that Icelandic glaciers would disappear in the coming centuries if the emission of greenhouse gasses continues the way it has. Vatnajökull might last the longest, especially its highest peaks.
Globally, melting glaciers might raise ocean levels, on average, one metre in this century. The development in Iceland is less clear. Due to factors such as land rising when the weight of glaciers is lifted, ocean levels might rise less, even drop in some places. Land rise due to glaciers melting might make volcanic eruptions more frequent. How exactly the ocean levels might change around Iceland is unknown because it depends on how quickly the polar ice caps melt, especially the south pole.