In 2002, within days of its 1 March 2002 launch, ESA's environmental satellite Envisat captured the disintegration of the Larsen-B ice shelf in Antarctica, surprising scientists because of the rapid rate at which the shelf broke apart.
Average temperatures in the Antarctic Peninsula have risen over the last 50 years by half a degree Celsius a decade and are having an impact on the ice shelves and glaciers. The ice retreat has been accelerating since 1992 and culminated in two collapse events: Larsen-A in January 1995 and Larsen-B in March 2002.
This poster compares images of the Larsen-B ice shelf taken during orbits 246 and 250, captured 18 March 2002, as seen by Envisat's Advanced Synthetic Aperture Radar (ASAR) instrument. The two images shown the disintegration of the 200-metre-thick Larsen-B ice shelf over several hours. Researchers estimate the ice shelf had been stable since the last ice age, 12 000 years ago.
The sections of Larsen-A, which disintegrated almost completely in January 1995, and Larsen-B, that broke away in 2002, were 200 to 350 metres thick.
After the collapse event in 2002, the outlet glaciers from the Antarctic Peninsula that previously nourished the ice shelf retreated many kilometres above the previous grounding line. Altogether about 250 square kilometres of grounded ice have been lost at the outlet glaciers of former Larsen-A and Larsen-B ice shelves.
The remoteness, darkness and cloudiness of Earth’s Polar Regions make them difficult to study. An instrument known as the Advanced Synthetic Aperture Radar (ASAR) allows Envisat to produce high-quality images of ice sheets because it is able to pierce through clouds and darkness.
Since the early 1990s, ESA has been able to provide near-continuous satellite data on the polar regions over long periods of time, which is essential for scientists to identify and analyse long-term climatic trends and changes. For instance, using radar altimeter data from ESA’s ERS-1 and ERS-2, scientists at NASA's Goddard Space Center mapped the height of the Antarctic and Greenland ice sheets and found there was a net loss of ice from the combined sheets between 1992 and 2002 and a corresponding rise in sea level.
Earth from Space: Larsen-B Ice Shelf on thin ice
Satellites shed light on global warming
Envisat operations
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