West Antarctic glaciers lost hundreds of metres of solid ice in the space of seven years, scientists have found. Between 2002 and 2009, the influx of warm ocean water beneath ice shelves in the Amundsen Sea led to widespread melting.

The remote Amundsen Sea is located over the extreme southern Pacific Ocean, off the coast of West Antarctica. Scientific exploration in this area and mapping of the sea structure only began in 1994 as researchers had previously struggled to reach this part of Antarctica because of difficult ice conditions. At this time, it was revealed that warm Circumpolar Deep Water had access to the continental shelf and could result in the melting of glaciers.

Over the past decades, more research has confirmed that the Amundsen Sea is home to some of the fastest melting glaciers on the planet – it is the region with the largest net mass loss of ice in Antarctica.

Scientists have also documented how flows of warm water pour into sub-ice shelf cavities and slowly erode the solid ice present in this area.

However, none of these studies had really quantified the magnitude of this ice loss. Thus this new study, published in the journal Nature, aimed to come up with accurate measurements.

Smith, Pope, and Kohler

The scientists, led by Ala Khazendar from California Institute of Technology, used airborne data collected as part of NASA's Operation IceBridge – a project which aims to capture images of the Earth's polar ice in unprecedented detail.

These images allowed the team to track down variations to three important Antarctic glaciers known as Smith, Pope, and Kohler. All are located in the Amundsen Sea embayment.

The data collected between 2002 and 2009 suggests that there was an important and unbalanced loss of ice on the three glaciers in the just seven years. Smith Glacier was particularly affected - it lost as much as 70 metres per year, and almost half a kilometre of ice thickness in total over the period.

glacier melting ice
The three glaciers lost a lot of ice since 2003. NASA

Data collected after 2009 show a continuation of this phenomenon, although to a lesser extent. Scientists have indeed discovered that the grounding line of Smith Glacier retreated into a deep trough, contributing to continued intense ice loss up to now. However, the situation on Pope and Kohler between 2009 and 2014 appears to have been less dramatic, with less ice loss reported over the period.

These findings indicate there was an increased influx of warm deep water pouring into sub-ice-shelf cavities in the mid-2000s, and this damaged the glaciers of the Amundsen Sea.