Arctic sea ice thinning faster than expected

Arctic sea ice thinning faster than expected

The full story can be found at Arctic sea ice thinning faster than expected | UCL Mathematical & Physical Sciences UCL University College London.

Sea ice in the coastal regions of the Arctic may be thinning up to twice as fast as previously thought, according to a new modelling study led by CPOM UCL researchers.

Sea ice thickness is inferred by measuring the height of the ice above the water, and this measurement is distorted by snow weighing the ice floe down. Scientists adjust for this using a map of snow depth in the Arctic that is decades out of date and does not account for climate change.

In the new study, published in the journal The Cryosphere, researchers swapped this map for the results of a new computer model designed to estimate snow depth as it varies year to year, and concluded that sea ice in key coastal regions was thinning at a rate that was 70% to 100% faster than previously thought.

Robbie Mallett (CPOM PhD researcher, UCL), the PhD student who led the study, said: “The thickness of sea ice is a sensitive indicator of the health of the Arctic. It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from the sunshine in summer. Thinner ice is also less likely to survive during the Arctic summer melt.”

“Previous calculations of sea ice thickness are based on a snow map last updated 20 years ago. Because sea ice has begun forming later and later in the year, the snow on top has less time to accumulate. Our calculations account for this declining snow depth for the first time, and suggest the sea ice is thinning faster than we thought.”

Co-author Professor Julienne Stroeve (CPOM Associate Investigator, UCL) said: “There are a number of uncertainties in measuring sea ice thickness but we believe our new calculations are a major step forward in terms of more accurately interpreting the data we have from satellites.”

“We hope this work can be used to better assess the performance of climate models that forecast the effects of long-term climate change in the Arctic – a region that is warming at three times the global rate, and whose millions of square kilometres of ice are essential for keeping the planet cool.”

To calculate sea ice thickness researchers used radar from the European Space Agency’s CryoSat-2 satellite. By timing how long it takes for radar waves to bounce back from the ice, they can calculate the height of the ice above the water, from which they can infer the ice’s total thickness.

In the new study, researchers used a novel snow model previously developed by researchers at UCL and Colorado State University, SnowModel-LG, which calculates snow depth and density using inputs such as air temperature, snowfall and ice motion data to track how much snow accumulates on sea ice as it moves around the Arctic Ocean. By combining the results of the snow model with satellite radar observations, they then estimated the overall rate of decline of sea ice thickness in the Arctic, as well as the variability of sea ice thickness from year to year.

They found that the rate of decline in the three coastal seas of Laptev, Kara and Chukchi seas increased by 70%, 98% and 110% respectively, when compared to earlier calculations. They also found that, across all seven coastal seas, the variability in sea ice thickness from year to year increased by 58%.

Sea ice in the coastal seas typically varies from half a metre to two metres thick. Increasingly, the ice in this region is not surviving the summer melt. The faster thinning of sea ice in the coastal Arctic seas has implications for human activity in the region, both in terms of shipping along the Northern Sea Route for a larger part of the year, as well as the extraction of resources from the sea floor such as oil, gas and minerals.


Credits: Alfred-Wegener-Institut / Niels Fuchs. Source: MOSAiC website.

Credits: Alfred-Wegener-Institut / Niels Fuchs. Source: MOSAiC website.

Mallett said: “More ships following the route around Siberia would reduce the fuel and carbon emissions necessary to move goods around the world, particularly between China and Europe. However, it also raises the risk of fuel spillages in the Arctic, the consequences of which could be dire. The thinning of coastal sea ice is also worrying for indigenous communities, as it leaves settlements on the coast increasingly exposed to strong weather and wave action from the emerging ocean.”

Mallett, Professor Stroeve and co-author Dr Michel Tsamados (CPOM Associate Investigator, UCL) spent several weeks investigating snow and ice in the Arctic onboard the German research vessel Polarstern, which explored the central Arctic Ocean in 2019 and 2020.

The study was funded by the UK’s Natural Environment Research Council, the European Space Agency (ESA), and the US National Aeronautics and Space Administration (NASA).

Dr Rosie Willatt bringing research to secondary schools

The full story can be found at: Bringing research to secondary schools. | UCL Earth Sciences at UCL University College London

Dr Rosemary Willatt, a CPOM Research Fellow delivers Secondary School Science Advisors programme.

Rosemary Willatt, a Research Fellow in UCL Earth Science’s Centre for Polar Observation and Modelling, has developed a new outreach idea based around a flipped learning approach and a reversed power dynamic between students and teachers. Working with the Geobus Leader, Amy Edgington, she presented information on her own work on remote sensing of sea ice, and gave secondary school students the chance to take an active role in the research through posing science questions for Rosie to research.

Martin Hains, a teacher at Leyton College, said:

“Collaborating with UCL has helped to develop our learner’s critical thinking skills. Students have gained first-hand experience of cutting-edge climate research and have been inspired to learn more about the polar regions and their impact on climate change.”

The students have come up with a series of fantastic questions for Rosie, many of which are active topics of research for her or other scientists, giving her the opportunity to develop her own thinking and to bring up-to-date climate science to the students. She hopes to work with other schools or colleges in future.

CryoSat reveals ice loss from glaciers in Alaska and Asia

Noel Gourmelen, CPOM Associate Investigator at University of Edinburgh, is amongst the authors of a recent study, which shows that mountain glaciers in the Gulf Alaska and in High Mountain Asia have lost 5% of their volume of ice over last decade. The full story can be found at ESA.

As our climate warms, ice melting from glaciers around the world is one of main causes of sea-level rise. As well as being a major contributor to this worrying trend, the loss of glacier ice also poses a direct threat to hundreds of millions of people relying on glacier runoff for drinking water and irrigation. With monitoring mountain glaciers clearly important for these reasons and more, new research, based on information from ESA’s CryoSat mission, shows how much ice has been lost from mountain glaciers in the Gulf Alaska and in High Mountain Asia since 2010.

Monitoring glaciers globally is a challenge because of their sheer number, size, remoteness and rugged terrain they occupy. Various satellite instruments offer key data to monitor change, but one type of spaceborne sensor – the radar altimeter – has seen limited use over mountain glaciers.

Traditionally, satellite radar altimeters are used to monitor changes in the height of the sea surface and changes in the height of the huge ice sheets that cover Antarctica and Greenland. They work by measuring the time it takes for a radar pulse transmitted from the satellite to reflect from Earth’s surface and return to the satellite. Knowing the exact position of the satellite in space, this measure of time is used to calculate the height of the surface below.

However, the footprint of this type of instrument is generally too coarse to monitor mountain glaciers. ESA’s CryoSat pushes the boundaries of radar altimetry and a particular way of processing its data “swath processing“ make it possible to map glaciers in fine detail.

A paper published recently in The Cryosphere describes how scientists used CryoSat to investigate ice loss in the Gulf of Alaska and High Mountain Asia.

They found that between 2010 and 2019, the Gulf of Alaska lost 76 Gt of ice per year while High Mountain Asia lost 28 Gt of ice per year. These losses are equivalent to adding 0.21 mm and 0.05 mm to sea level rise per year, respectively.

Livia Jakob, from Earthwave, explains, “One of the unique properties of this dataset is that we can look at ice trends at exceptionally high resolution in space and time. This enabled us to discover changes in trends, such as the increased ice loss from 2013 onwards in parts of the Gulf of Alaska, which is linked to climatic changes.”

The study, which was carried out through ESA’s Science for Society programme, also shows that almost all regions have lost ice, with the exception of the Karakoram-Kunlun area in High Mountain Asia, a phenomenon known was the “Karakoram anomaly”.

Noel Gourmelen, CPOM Associate Investigator at University of Edinburgh, is amongst the authors of a recent study, which shows that mountain glaciers in the Gulf Alaska and in High Mountain Asia have lost 5% of their volume of ice over last decade. The full story can be found at ESA.

As our climate warms, ice melting from glaciers around the world is one of main causes of sea-level rise. As well as being a major contributor to this worrying trend, the loss of glacier ice also poses a direct threat to hundreds of millions of people relying on glacier runoff for drinking water and irrigation. With monitoring mountain glaciers clearly important for these reasons and more, new research, based on information from ESA’s CryoSat mission, shows how much ice has been lost from mountain glaciers in the Gulf Alaska and in High Mountain Asia since 2010.

Monitoring glaciers globally is a challenge because of their sheer number, size, remoteness and rugged terrain they occupy. Various satellite instruments offer key data to monitor change, but one type of spaceborne sensor “the radar altimeter“ has seen limited use over mountain glaciers.

Traditionally, satellite radar altimeters are used to monitor changes in the height of the sea surface and changes in the height of the huge ice sheets that cover Antarctica and Greenland. They work by measuring the time it takes for a radar pulse transmitted from the satellite to reflect from Earth’s surface and return to the satellite. Knowing the exact position of the satellite in space, this measure of time is used to calculate the height of the surface below.

However, the footprint of this type of instrument is generally too coarse to monitor mountain glaciers. ESA’s CryoSat pushes the boundaries of radar altimetry and a particular way of processing its data “swath processing“ make it possible to map glaciers in fine detail.

A paper published recently in The Cryosphere describes how scientists used CryoSat to investigate ice loss in the Gulf of Alaska and High Mountain Asia.

They found that between 2010 and 2019, the Gulf of Alaska lost 76 Gt of ice per year while High Mountain Asia lost 28 Gt of ice per year. These losses are equivalent to adding 0.21 mm and 0.05 mm to sea level rise per year, respectively.

Livia Jakob, from Earthwave, explains, “One of the unique properties of this dataset is that we can look at ice trends at exceptionally high resolution in space and time. This enabled us to discover changes in trends, such as the increased ice loss from 2013 onwards in parts of the Gulf of Alaska, which is linked to climatic changes.”

The study, which was carried out through ESA’s Science for Society programme, also shows that almost all regions have lost ice, with the exception of the Karakoram-Kunlun area in High Mountain Asia, a phenomenon known was the “Karakoram anomaly”.

Noel Gourmelen, from the University of Edinburgh, said, “It is astonishing to think that over last decade alone, both regions have lost 5% of their volume of ice. What CryoSat has accomplished also is astonishing. While glaciers were a secondary objective of the mission, few would have thought possible to use radar altimetry in regions with extremely complex topography like High Mountain Asia and the Gulf of Alaska.

“But thanks to a brilliant altimeter design, dedicated support from ESA, and many years of research by the community, interferometric radar altimeters are now part of the toolset to monitor glacier change globally.”

This research, as well as that published in a related paper covering the entire Arctic region apart from Greenland, demonstrates that this unique high-resolution radar altimetry dataset can provide crucial information to better quantify and understand glacier changes on a global scale. This also opens up possibilities to monitor glaciers globally with satellites such as the planned CRISTAL mission, part of the expansion of Europe’s Copernicus programme.