Non-linear response of glacier melting to Holocene warming in Svalbard recorded by sedimentary iron (oxyhydr)oxides

• Published in: Earth and Planetary Science Letters
• Main Authors: Jang, Kwangchul, Bayon, Germain, Vogt, Christoph, Forwick, Matthias, Ahn, Youngkyu, Kim, Jung-hyun, Nam, Seung-il
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2023
• Subjects: iron (oxyhydr)oxides; high Arctic environments; glacier retreat; tipping point; accelerated glacier melting; neodymium isotopes; Arctic; Svalbard; Climate change; glacier; Ice Sheet; Subarctic
• Online Access: https://archimer.ifremer.fr/doc/00824/93566/100289.pdf; https://archimer.ifremer.fr/doc/00824/93566/100290.docx; https://archimer.ifremer.fr/doc/00824/93566/100291.xlsx; https://doi.org/10.1016/j.epsl.2023.118054; https://archimer.ifremer.fr/doc/00824/93566/

The recent acceleration of ice-sheet loss with its direct impact on sea-level rise and coastal ecosystems is of major environmental and societal concern. However, the effect of atmospheric temperature increases on long-term glacier retreat remains poorly defined due to limited historical observations and uncertainties in numerical ice-sheet models, which challenges climate change adaptation planning. Here, we present a novel approach for investigating the time-transgressive response of Arctic glaciers since the last deglaciation, using glacially-derived Fe-(oxyhydr)oxide layers preserved in glacimarine sediments from a large fjord system in Svalbard. Glacial weathering releases large amounts of Fe, resulting in the deposition of Fe-(oxyhydr)oxide particulates in nearby marine sediments, which can serve as fossil indicators of past glacial melting events. Our results indicate that Svalbard glaciers retreated at a rate of 18 to 41 m/yr between 16.3 and 10.8 kyr BP, synchronously with the progressive rise in atmospheric and oceanic temperatures. From 10.8 kyr BP, glacier retreat markedly accelerated (up to ∼116 m/yr) when regional atmospheric temperatures exceeded modern values. Coupled with field observations, this finding directly supports a non-linear response of glacial melting to summer air temperature increases. In addition to suggesting that ice-sheet loss and sea-level rise may further accelerate in the near future, this study paves the way for the use of sedimentary Fe-(oxyhydr)oxide layers in subarctic environments for reconstructing past glacial dynamics.