Zombie glaciers? Some 'dead' glaciers come back to life, sloughing off parts of themselves in the process
Wednesday, October 29, 2014, 4:47 PM - A large glacier in southeastern Iceland is apparently joining in the 'zombie' craze that's been sweeping the world in recent years, as it adjusts to the increasingly disruptive influence of climate change.
Glaciers, as the ice contained within them continues to flow downward towards their forward margin, generally wax and wane with the seasons, growing and thickening during the colder months and retreating during the warmer ones. However, due to the excess greenhouse gases being emitted into the atmosphere by human activities, and the global warming and climate change that's resulting from it, that pattern is being disrupted. This has put many glaciers into a state of constant retreat, where the only real difference seen between the seasons is the rate at which they're disappearing.
Normally, when in a state of retreat, there's two ways that a glacier goes about it.
Some continue to wax and wane along their leading edge - retreating with the spring and summer heat, then advancing in the fall and winter (but nowhere near as far as the previous year), and then retreating again to a new extreme when the heat returns. This can be said to describe a glacier that's still 'alive' even though it continues to show a trend of lose ice.
Others, rather than continuing this advance and retreat every year, instead become 'dead ice' - stagnating and simply melting away in place.
However, on a recent trip to Iceland's Falljökull glacier, a team of scientists from the British Geological Survey (BGS) discovered that this icesheet is somewhere between 'alive' and 'dead' - in effect, a zombie glacier.
Jez Everest, a glacial geologist with the BGS, told the American Geophysical Union: "Over the past two decades due to the increasingly warmer summers and milder winters Iceland’s glaciers have been retreating at a dramatically accelerated rate."
CLICK BELOW TO WATCH: Jez Everest discusses the importance of glacier monitoring and the British Geological Survey's role in watching Iceland's glaciers
This rapid retreat of the Falljökull glacier has caused it to react in a completely unprecedented way.
"We took a fully 3D view deep inside Falljökull and what we saw was rapid changes in the structure, a form of ‘downsizing’, to adjust to the changes in climate," said Emrys Phillips the lead author of the study, soon to be published in the AGU's Journal of Geophysical Research: Earth Surface, according to the statement.
What happened was that the margin of Falljökull, which had been active but retreating between 1990 and 2004, stopped moving altogether between 2004 and 2006, and began to very quickly melt away in place. With this 'death' of the ice at the margin, the upper part of the glacier continued to flow, revealing a semblance of life. Furthermore, the 'living' part of the glacier is actually overriding the dead portion.
"This type of behavior has never been described before," Phillips said, according to the AGU, adding "We think that other steep, mountain glaciers around the world may be responding in a similar way, rapidly adjusting their active length in response to recent warming of the climate."
(H/T to John Upton at ClimateCentral.org)