We used 1,000 historical photos to reconstruct Antarctic glaciers before a dramatic collapse

By Ryan North, University of Wollongong, Tim Barrows, UNSW Sydney

In March 2002, the Larsen B Ice Shelf collapsed catastrophically, breaking up an area about one-sixth the size of Tasmania.

In a paper published today in Scientific Reports, we used nearly 1,000 film photographs of Antarctica from the 1960s to reconstruct exactly what five glaciers were like decades before the Larsen B Ice Shelf collapse. This allowed us to precisely calculate their contribution to sea-level rise.

Although Antarctica is far away, and changing conditions there may seem distant, the changes can have a profound effect for us all. The removal of an ice shelf can cause glaciers to rapidly melt into the ocean and raise global sea levels.

After consecutive years of unusually warm temperatures, the Larsen B Ice Shelf collapsed over the course of a week. This induced dramatic change for the glaciers that used to flow into it. The glaciers have since been thoroughly monitored – but there were few observations of them before 2002.

However, an archive of more than 300,000 historical images contains an invaluable record of this area from 1968 and helped us measure the difference between then and now.

Observing glaciers

Ice shelves are thick floating bodies of ice attached to the coastline of Antarctica. The melting of an ice shelf does not directly cause sea-level rise.

However, ice shelves “hold back” the flow of glaciers. Once the shelves are removed, glaciers rapidly melt into the ocean. This transfers ice from the land to the ocean and causes sea-level rise.

To accurately predict how Antarctica’s glaciers will respond to future climate change, it is critical to understand how they have responded in the past. But some places in Antarctica are so remote, it is almost prohibitively difficult and expensive to get there and gather data.

Scientists often look to satellites to collect data because it is relatively cheap and easy.

Read Full Story https://theconversation.com/we-used-1-000-historical-photos-to-reconstruct-antarctic-glaciers-before-a-dramatic-collapse-233972