Sudden glacial melts could release Amazon-like floods

As the climate warms, glaciers don’t always melt slowly. In fact, new research indicates that glaciers on volcanoes in places like Iceland can melt rapidly, releasing large volumes of water as powerful as the Amazon River.

Andy Russell, a scientist at Newcastle University, said such floods could hit parts of Europe within decades. He and his research team this week published their first comprehensive review of such volcano-connected flooding impacts in the journal Developments in Quaternary Sciences.

Such flooding events — which can dramatically alter the surrounding landscape — are actually relatively frequent in Iceland, where a large sub-glacial eruption is long overdue, according to Russell’s research. In the past, the region has seen enormous volumes of water and sediment suddenly entering the ocean during these floods, which can also generate tsunamis and extend the coastline by several kilometres within hours.

The new study focuses on Mýrdalsjökull, Iceland’s southernmost glacier.

“Knowledge of how outburst floods behaved previously enables us to better predict the impacts of future events and allows us to develop appropriate strategies to lessen their impact on the surrounding population,” said Russell. “We can’t predict or stop nature, but we can be prepared for it when she blows.”

Russell has been working with other researchers and Earthwatch volunteers in Iceland for the last 10 years.

“There are still many gaps in our understanding and we are realising that meltwater can find its way out of glaciers much more quickly than previously thought,” he said. “We’re looking at the possibility of a flow the size of the Amazon being released within less than an hour and that doesn’t give people much time to get out of way.

“The potential impact of much of our work is in helping to inform both the local population and the civil defence authorities to ensure they are as prepared as possible.”

Russell observed firsthand how quickly the environment can change in response to the rapid receding and shrinking of glaciers. During this past summer’s fieldwork, he watched the demise of Iceland’s largest glacial river, the Skeiðará, which started flowing on a new drainage path, along the glacier margin into the Gígjukvísl River.

“The impacts of this event were spectacular,” Russell said. “The levels in two iceberg-infested lakes at the glacier margin rose and water levels in a further three lakes dropped.

“Newly-routed water sliced through the glacier margin like a hot knife through butter. River channels between the lake basins experienced major growth over just ten days.

“This spectacular event illustrates dramatically how climate change can lead to sudden environmental change.”

Today, water no longer flows in the Skeiðará River system. Coupled with the nature of the whole outwash system, these changes so close to the glacier are likely to have significant impacts further downstream and within the coastal zone in the future, according to Russell.