Artists impression of CryoSat-2 in space. Image courtesy of ESA – P. Carril.

As the UK is basking in its first prolonged spell of sunshine for some time, we’re focusing on colder parts of the world in the blog looking at the latest news in terms of ice monitoring.

We’re starting with some research by Jakob and Gourmelen et al. as part of ESA’s Science for Society programme, which was recently published in The Cryosphere entitled ‘Spatially and temporally resolved ice loss in High Mountain Asia and the Gulf of Alaska observed by CryoSat-2 swath altimetry between 2010 and 2019’.

The researchers used data from the Synthetic Aperture Interferometric Radar Altimeter (SIRAL) onboard the Cyrosat-2 mission, which operates in the Ku Band, to map the glaciers. Radar altimeters work by measuring the time it takes for a radar pulse transmitted from the satellite to reflect from Earth’s surface and return, this time can be used to calculate the height of the surface it reflected from on Earth. They normally measure ice sheets and sea surface changes, but are rarely used on mountain glaciers, which makes this work interesting as it is Cryosat-2’s swath processing technique that enables it to map the glacial details.

The team used 33 million elevation measurements between 2010 and 2019 for the two mountain regions of the Gulf of Alaska and High Mountain Asia. They found that the Gulf of Alaska lost 76 Gt of ice per year, while High Mountain Asia lost 28 Gt of ice per year.

As well as the worrying loss of this ice, it also has other impacts as these losses are equivalent to adding 0.21 mm and 0.05 mm to sea level rise per year and there are millions of people relying on glacier runoff for drinking water and irrigation.

The second piece of recently published research was undertaken by a team from the Centre for Earth Observation Science at the University of Manitoba. The paper written by Crawford and Stroeve et al. was entitled ‘Arctic open-water periods are projected to lengthen dramatically by 2100’, and was published in the Nature journal Communications Earth & Environment.

The impact of global warming on the seasonal retreat and advance of Arctic sea ice has been known for some time, and this research provides future predictions on how this will change over time in scenarios of global average temperature increase of 2°C to 5°C. Their results indicate that for every 1°C of global warming, the open-water period (on average) increases by about 1 month in the Arctic – although there is a faster change in the Arctic Ocean, compared to the sub-Arctic seas.

A few other key takeaways from this research are:

• There is no tipping point for the open-water period, any increase in warming directly impacts the length of this open water period.
• The Transpolar Sea Route, which is an important path for a container ship to go from Japan to Europe, through Bering Strait and across the North Pole, would be consistently open for at least 3 months of the year with 3.5°C of warming. At least 6 months with 5°C warming. Whereas currently, it is only open for around eight weeks.
• Comparing climate models to satellite observations indicates the models have been accurate in predicting what is happening.

Finally, news of the outcome of a battle in the Wendell Sea in Antarctica that’s been raging for a couple of months! It’s the title of the world’s largest iceberg!

In May this year, when iceberg A-76 was calved from the Antarctic’s Ronne Ice Shelf it became the world’s largest floating iceberg measuring around 1 668 square miles. However, just one month later A-76 has broken into three pieces – known as A-76A, A-76B and A-76C – and lost its title. Instead, iceberg A-23A has reclaimed the title, as it measures around 1 500 square miles!

As the blog shows, even the polar regions have exciting news!