Ny publikasjon i Nature Geoscience

Around 14,600 years ago, toward the end of the most recent ice age, large portions of the northern and southern hemisphere were covered with a thick ice sheet. Within a few hundred years, a period of rapid warming led to increased melting of the ice sheets all over the globe. This went along with a global sea-level rise of up to 14 meters. Prior research results implied that most of the ice sheet covering Northern Europe – the Eurasian Ice Sheet (EIS) – had already melted before this rapid warming period, and that only a minor amount of meltwater from ice sheets in the northern hemisphere around this time came from the EIS.

But Jo, Bjarte, and Kristian, together with colleagues from the Department of Earth Science at UiB, as well as from the University of Tokyo, questioned these assumptions. By investigating marine sediment cores from the Norwegian Sea they improved the timeline for what happened between 21,000 and 12,500 years ago. Carbon-14 dating is the perfect tool when wanting to date marine sediments, but the calibration curves for C-14 commonly used until now had flaws. This study eliminated the flaws by creating a regional calibration curve specific for the Norwegian Sea and provides much more accurate age results, the previously used calibration curves gave ages “too old” by 1,500 – 1,700 years.

Including this age difference, the new results by Jo Brendryen and his colleagues, imply that the EIS had, in fact, not melted prior to the rapid warming event starting around 14,600 years ago, but melted during that exact period, along with other ice sheets globally. It may have provided around half of the meltwater responsible for the drastic sea-level rise during that time!

These findings indicate that massive ice sheets are very sensitive to climate and can vanish within only a few hundred years. The West Antarctic Ice Sheet we see in the southern hemisphere today is comparable in size to what the EIS used to be before the ice-sheet collapse.

Better predicting future sea-level rise is one of the great challenges in climate science, and we are proud that researchers from the Jebsen Centre are advancing this field with this study, which you can find online here: https://www.nature.com/articles/s41561-020-0567-4

A view-only version of the article can be found here: https://rdcu.be/b3FGa

A News & Views article on the publication is also available on the Nature homepage: https://www.nature.com/articles/s41561-020-0572-7

A popular science summary can also be found on the Bjerknes Centre homepage, in both

Norwegian https://www.bjerknes.uib.no/artikler/nyheter/bra-oppvarming-forarsaket-iskollaps-og-havnivastigning

and English https://www.bjerknes.uib.no/en/article/news/abrupt-warming-caused-ice-collapse-and-sea-level-rise