Sea ice lows high on the agenda
Satellite observations reveal that the extent of sea ice in the Arctic is once again hovering near record lows for this time of year ? underscoring a troubling and persistent trend. This issue is a key topic at ESA's Living Planet Symposium in Vienna, where scientists are emphasising the critical role that ESA's Climate Change Initiative Sea Ice Project and CryoSat mission have had in helping to underpin these findings.
Looking ahead, the ability to monitor polar sea ice is in safe hands, as the development of the new CRISTAL mission is progressing well and the first satellite will be ready for launch in the second half of 2027.
Thanks to satellites carrying radar instruments, we have year-round observations of the remote Arctic and Antarctic polar regions, which are shrouded in darkness during their long winter months.
Over decades, satellites have allowed scientists to witness how the sea ice in both regions naturally grows during the winter and declines during the summer, along with the toll that the climate crisis is having on this fragile component of our Earth system.
Sea ice plays a complex role in the climate system. As ice declines the amount of sunlight absorbed by the ocean increases, leading to warmer ocean waters.
As well as affecting water temperature, when ice melts the surface waters become less saline ? these changes in temperature and salinity contribute to modifications in ocean circulation patterns, which in turn influence weather systems and climate across the planet.
The Arctic, often referred to as the ?canary in the coal mine', is at the frontline of climate change, warming faster than anywhere else on the planet. This is leading to knock-on effects, known as Arctic amplification, that have profound implications for the rest of the world.
ESA's Climate Change Initiative (CCI) Sea Ice Project datasets, compiled from various satellite altimeter data such as that from ESA's CryoSat and the Copernicus Sentinel-3 mission, are available to help predict how much sea ice we will have in the future, particularly in September when, in the Arctic, sea ice dips to its minimum.
These predictions are done through models, which can be based on different greenhouse-gas emission scenarios. Output from the Sea Ice Project provides crucial support to long-term climate monitoring and informs policy-making.
ESA Cryosphere Scientist, Anna Maria Trofaier, said, "As with all of the ESA CCI projects we develop long-term data records of essential climate variables. Through our Sea Ice Project, we are about to release a new dataset for sea ice thickness from radar altimeter data.
"This will be the longest yet consistent timeseries of sea ice thickness ? ranging from today's Copernicus Sentinel-3 and CryoSat missions back to the ERS-2 period in the mid-1990s.
"This long record is extremely valuable for analysing the trend of diminishing sea ice. Sea ice is getting thinner, sparser and more vulnerable, but there is yet more to learn.
"To better capture the complexity of the processes that have led to the current state of sea ice, we also need to look at the lifetime of the ice parcels, as this is linked to the dynamic and thermodynamic growth of sea ice. For this reason, ESA is also starting a new project that focuses on the different types of sea ice and their age and how ice age is closely tied to sea ice drift."
These sea ice records use data from numerous missions such as ESA's heritage ERS and Envisat satellites, and over the last 15 years, ESA's CryoSat mission.
Remarkably, CryoSat, an Earth Explorer mission developed within ESA's FutureEO programme has reached the ripe old age of 15 and is still going strong.
Its main instrument is a synthetic aperture interferometric radar altimeter, which was the first sensor of its kind designed for ice, measuring changes on and at the margins of vast ice sheets, and over floating ice in polar oceans.
A recent study published in the Annals of Glaciology offers a dynamic view of how sea-ice drift, growth, and melt across key regions of the Arctic interact to drive interannual changes in sea-ice volume over the past decade. These insights have been made possible thanks to ESA's CryoSat mission, which has more than proven the value of its innovative technology in monitoring Earth's ice cover from space.
However, CryoSat's life in orbit cannot last forever so attention is turning to the future of polar monitoring.
Enter CRISTAL ? the Copernicus Polar Ice and Snow Topography Altimeter ? building on CryoSat's legacy with enhanced capabilities. It will carry the first Ku/Ka dual-frequency radar altimeter that will measure and monitor sea-ice thickness, overlying snow depth and ice-sheet elevation.
With the decline of sea ice remaining a pressing concern on the global climate agenda, the upcoming CRISTAL mission, one of six missions significantly expanding the observing capabilities of Copernicus, has been a key topic of interest at ESA's Living Planet Symposium, where scientists and stakeholders are eager to learn what this next-generation satellite will deliver.
The mission is made up of two identical satellites that will be launched sequentially to ensure the continuity of data delivery well into the 2040s.
ESA's CRISTAL Mission Scientist, Paolo Cipollini, explained, "A major source of uncertainty in measuring sea-ice thickness stems from the presence of an overlying snow layer.
This is where CRISTAL will make a significant difference. Equipped with the dual-frequency altimeter, it will be able to measure snow depth directly, allowing for more accurate corrections in sea ice thickness estimates."
The mission is making good progress ? assembly of the first satellite, CRISTAL-A, is well underway at Airbus Defence and Space in Friedrichshafen, Germany.
Thank you for reading the article! Follow us at Google News.
