Since the launch of the first Earth-observing satellites in the 1970s, numerous missions from international space organisations have taken to the sky. Today, decades of data are helping scientists to build a better picture of changes to our planet.

Between 2008 and 2009, a 750 sq km-area of ice in the northern Antarctic – known as the Wilkins Ice Shelf – partly disintegrated. At the time, ESA’s Envisat satellite monitored the event with the help of the DLR German Aerospace Center’s TerraSAR-X mission.

While the event itself made headlines, scientists got to work studying the ice’s behaviour before the break-up and continued to monitor the area for years afterward.

In a study published recently, a team of researchers from the German university Erlangen-Nürnberg examined data dating back to 1994 from the ERS mission to map the ice speed on the Wilkins Ice Shelf up through 2010 using Envisat, TerraSAR-X and Japan’s ALOS.

Measuring the speeds over different periods, the team discovered that while very stable in the mid-1990s, the major ice-front retreat in 2008 greatly affected upstream ice-shelf areas, causing an increase. This suggests that the area of ice lost was responsible for restraining upstream ice.

Monitoring the behaviour of ice yields important information for climate change modelling.

But in order to monitor changes in ice – or any other climate variables such as sea levels, greenhouse gases or land cover – over long periods, it is imperative that there are no gaps in the data.