In today’s blog post, you can read about a pressing topic related to climate change and sea level rise. Recently, the Guardian reported on a Nature publication that was published in early April summarizing the latest findings of a British-Norwegian collaboration studying marine sediments from the last ice age.
Antarctic Ice Sheet. Image Credit; ESA
Focusing on bathymetric data off the Norway coast, the scientists suggest that ice sheets can collapse at much faster rates than believed before. Previous studies approximated the retreat at ‘up to 100 m per day’ but now the researchers uncovered a collapsing rate of ‘up to 600 m per day’ leading to a faster rate of sea level rise and hence a more urgent and significant impact for coastal cities and communities across the globe.
The authors mapped sets of small ridges of sediments deposited parallel to the Norwegian coast where the past (and now gone) Norwegian ice sheet met the ocean (this location is called the grounding line) during the last ice age. When the ice sheet started retreating, the grounding line did too, creating sets of successive ridges. By measuring the distance between the ridges, the authors could calculate how fast the ice sheet retreated. Generally, satellite images are used but with this method you can only go back over the past 30-50 years. Sedimentological studies have the advantages of going back much further in time, in this case, 20,000 years ago.
“Our research provides a warning from the past about the speeds that ice sheets are physically capable of retreating at,” said Dr Christine Batchelor at Newcastle University in the UK, who led the research. “It shows that pulses of rapid retreat can be far quicker than anything we’ve seen so far.” The Guardian.
But what does it mean in our day to day lives, an ice sheet retreat that can be as much 600 m a day? According to the lead author of the research, it is about 20 times faster than the fastest ever observed ice sheet retreat (a glacier in Antarctica) which implies that sea level rise could happen a whole lot faster than projected so far.
Guardian graphic. Source: Batchelor et al, 2023, Nature
The implications of these fast-ice sheet retreat rates for predicted global sea level rise will be determined by how long these fast rates can be kept going. The authors only observe the fastest speeds of retreat (600 m per day ) for 11 days for the Norwegian coast, but “The implications of such rapid retreat are serious, given the generally irreversible nature of ice sheet retreat” say the authors.
Want to read more about this relevant research? You can access the publication here or read the article written by the Guardian.