3D seismic survey of a tunnel valley. Image: Gardline
Scientists have captured surreal images of bygone ice age landscapes that are now buried under the seafloor between Great Britain and northern Europe. The ancient scenery includes enormous meltwater channels, called tunnel valleys, that were originally probed by sophisticated seismic surveys on behalf of oil and gas companies. A team led by James Kirkham, a PhD student at the British Antarctic Survey (BAS), have used the unprecedented data to peer back in time at ice ages over the past million years, a record that contains important clues about how modern ice sheets could respond to human-driven climate change.
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The team’s research “marks the first time that abundant glacial landforms have been convincingly imaged within buried [tunnel valleys] in the North Sea,” according to a study published on Wednesday in the journal Geology.“People have identified these channels and mapped them, but we've never before been able to really see the detail of what's inside the channels and how they were filled,” said Robert Larter, a marine geophysicist at the BAS who co-authored the study, in a call. “When you go back and look at the older 3D seismic data sets, which are lower resolution, it's like looking through fuzzy glasses in comparison to the new data,” he added. “You can see some of these features when you know they are there, but it really is like getting a better pair of spectacles, or going to the optician and getting the right prescription.”The dramatic images offer a rare look inside massive ice sheets that advanced and receded across the United Kingdom and Europe, and reveal 19 tunnel valleys that range in width from 1,000 feet to nearly two miles. Within these huge rivers, Kirkham and his colleagues were able to discern extremely small features, just a few feet wide, that shed light on the interior drainage mechanisms of the ice sheets.“These data are fantastic in their detail,” Larter said. “The limitation is that they cover quite small areas, so we can't go out and map the whole of the North Sea in this kind of detail. But we can do process studies looking at a few of these channels and understanding how they formed, which people couldn't do before.”
Scientists have spent decades trying to understand the formation and evolution of channels within modern ice sheets, like those in Greenland or Antarctica, but these efforts have become far more pressing alongside the escalation of human-driven climate change. Warmer temperatures are causing a decline of ice sheets and glaciers that is contributing to sea level rise, among other anthropogenic effects. A more precise understanding of ice sheet interiors could help to predict how these critical structures will transform in the coming centuries.Given that fossil fuel consumption is the main driver of the climate crisis, and the fact that the data was obtained at the behest of fossil fuel companies investigating offshore oil and gas reserves, Larter called the new study a “swords to ploughshares” approach to resolving questions about climate change.The fossil fuel industry is “only interested in one thing, really, in the data,” he said, “but there is so much more in 3D seismic data and a lot of university academics make use of it.”In addition to providing a spectacular view of these buried ancient landscapes, the seismic imagery can fill in some of the gaps in our knowledge of how ice sheets respond to periods of climate change. Far more observations and research will be needed before this kind of data can be directly applied to modern climate projections, but the new study has helped to literally map out the groundwork for those applications.“We're at an early stage, I think, and there's a long way to go,” Larter said. “But ultimately what we hope is that you will see this incorporated into the sort of models that are doing predictions of how the Antarctic and Greenland ice sheets are going to behave in the future.”“We now understand better how these things were formed, but there's still a lot more questions than answers,” he concluded. “But that's how research progresses: baby steps.”