Long-term measurements document sea level rise in the Arctic
Tracking down climate change with radar eyes: Over the past 22 years, the sea level in the Arctic Ocean has risen an average of 2.2 millimeters per year. This is the conclusion of an investigation performed jointly by DTU Space and DGFI-TUM as part of ESA's Sea Level Climate Change Initiative (CCI) project.
The most complete and precise overview of the sea level changes in the Arctic Ocean to date was obtained after evaluating 1.5 billion radar measurements of various altimetry satellites. A major challenge for a comprehensive analysis is the presence of sea ice which covers vast areas of the Arctic Ocean and obscures the ocean surface underneath. Applying DGFI-TUM's dedicated retracking algorithm ALES+ to ENVISAT and ERS-2 original measurements, radar echoes reflected even from small water openings in the ice could be identified and analysed. After harmonizing observation data from ice-covered and open water areas, maps of monthly sea level elevations were computed for 1996-2018.
Analysis of the long-term measurements revealed significant regional differences of sea level trends: Within the Beaufort Gyre north of Greenland, Canada and Alaska, the water stage rose twice as fast as on average. Low-salinity meltwater collects here, while a steady east wind produces currents that prevent the meltwater from mixing with other ocean currents. Along the coast of Greenland, on the other hand, the sea level is falling, on the west coast by more than 5 mm per year. Here, the melting glaciers weaken the gravity attraction. More information about the study can be found in the open access article Arctic Ocean Sea Level Record from the Complete Radar Altimetry Era: 1991–2018 (Remote Sensing, 2019, DOI: 10.3390/rs11141672, [PDF]). The results are also subject of a TUM press release (English, German).
Arcisstraße 21
80333 München