Earth’s shifting ice

Using data from ESA’s CryoSat mission, scientists have produced the best maps yet of the changing height of Earth’s biggest ice sheets.

CryoSat measures the height of ice – both of that floating in the polar oceans and of the vast ice sheets covering Greenland and Antarctica. This information is essential for working out the thickness of the ice and how it is changing and, ultimately, how the volume of Earth’s ice is being affected by the climate.

Their preliminary assessment is very close to that produced from gravity-sensing satellites, which currently see Greenland losing over 250 billion tonnes of ice a year.

However, CryoSat brings important additional detail to the picture.

It allows the team to study changes across the entire ice sheet at fine resolution, meaning the scientists are able to monitor the behaviour of individual glaciers.

Carrying an advanced radar altimeter, CryoSat orbits Earth at just over 700 km, reaching latitudes of 88° north and south to maximise its coverage of the poles.

The radar altimeter is not only able to detect tiny variations in the height of the ice but also measure sea level with unprecedented accuracy.

As the animation shows, the mission’s measurements of sea level incidentally also map the topography of the ocean floor, revealing thousands of previously unchartered ‘seamounts’, ridges and deep ocean structures.

This animation visualises the changes the satellite has seen on Earth since its launch in 2010.