Researchers have discovered that large volumes of the powerful greenhouse gas methane are being discharged from an Icelandic glacier.
A study of Sólheimajökull glacier, which flows from the active, ice-covered volcano Katla, reveals that up to 41 tons of methane are being released through meltwaters daily during the summer months. This is approximately equivalent to the methane produced by over 136,000 belching cows.
The Lancaster University-led research, which is featured in Scientific Reports, is the first published field study to indicate the release of methane from glaciers on this scale.
“This is a huge amount of methane lost from the glacial meltwater stream into the atmosphere,” said Dr Peter Wynn, a glacial biogeochemist from the Lancaster Environment Centre and corresponding author of the research. “It greatly exceeds average methane loss from non-glacial rivers to the atmosphere reported in the scientific literature. It rivals some of the world’s most methane-producing wetlands; and represents more than twenty times the known methane emissions of all Europe’s other volcanoes put together.”
Dr Wynn added: “Methane has a global warming potential 28 times that of carbon dioxide (CO2). It is therefore important that we know about different sources of methane being released to the atmosphere and how they might change in the future.
“There has been a lot of speculation about whether or not glaciers can release methane. The beds of glaciers contain the perfect cocktail of conditions for methane production—microbes, low oxygen, organic matter, and water—along with an impermeable cap of ice on the surface trapping the methane beneath.
“However, nobody has thoroughly investigated this in the field before and this is the strongest evidence yet that glaciers are releasing methane.”
The study is based on a PhD research done by Dr Rebecca Burns when she was a graduate researcher at Lancaster University through the Centre for Global Eco-innovation, partly sponsored by the European Regional Development Fund.
Dr Burns got water samples from the edge of the meltwater lake in front of the Sólheimajökull glacier and calculated the methane concentrations, comparing them with methane levels in adjacent sediments and other rivers, to ensure that the methane was not being released from the neighboring landscape.
“The highest concentrations were found at the point where the river emerges from underneath the glacier and enters the lake. This demonstrates the methane must be sourced from beneath the glacier,” Dr Wynn explains.
With a mass spectrometer, which identifies the exclusive ‘fingerprint’ of the methane, the scientists found the methane is being released from microbiological activity at the bed of the glacier. But there is still a link with the volcano.
We believe that while the volcano is not producing the methane, it is providing the conditions that allow the microbes to thrive and release methane into the surrounding meltwaters.
Dr Peter Wynn, Glacial Biogeochemist, Lancaster Environment Centre
Usually, when methane is exposed to oxygen, it joins to form CO2, so the methane effectively vanishes. On a glacier, meltwaters high in dissolved oxygen access the bed of the ice mass and convert any existing methane into CO2.
Understanding the seasonal evolution of Sólheimajökull’s subglacial drainage system and how it interacts with the Katla geothermal area formed part of this work.
Fiona Tweed, Research Co-Author, Professor, and Expert in Glacier Hydrology, Staffordshire University
At Sólheimajökull when the meltwater touches the glacier bed, it comes into contact with gases generated by the Katla volcano. These gases reduce the oxygen content of the water, meaning some of the methane generated by the microbes can be dissolved into the water and transported out of the glacier without being changed to CO2.
Dr Hugh Tuffen, a volcanologist at Lancaster University and co-author on the research, said: “The heat from Katla volcano may greatly accelerate the generation of microbial methane, so in fact, you could see Katla as a giant microbial incubator.
“Scientists have also recently discovered that Katla emits vast amounts of CO2—it’s in the top five globally in terms of CO2 emissions from volcanoes—so Katla is certainly a very interesting, very gassy volcano.”
“Both Iceland and Antarctica have many ice-covered, active volcanoes and geothermal systems," said Dr Burns. “The recent International Panel on Climate Change (IPCC) report highlights that current trajectories indicate global warming is likely to reach 1.5 °C between 2030 and 2052, with greatest perceived climate sensitivity at higher latitudes. If methane produced under these ice caps has a means of escaping as the ice thins, there is the chance we may see short-term increases in the release of methane from ice masses into the future.”
Andri Stefánsson, Professor of Hydrothermal Geochemistry at the University of Iceland, who was not involved in the research said: “These findings provide important and new information on the origin and fluxes of methane at the Earth’s surface and the significance of this greenhouse gas to the atmosphere from such systems.”
However, the scientists caution that it is still vague how these effects will take place. They are certain that although there could be a short-term spike of methane discharged while the glacier melts and thins, in the long-term the process could be self-limiting as, together with other reasons, without the ice, the settings for methane production are eliminated.
This study included collaborative business partner Elementar UK Ltd. The investigation was undertaken in partnership with the Centre for Ecology & Hydrology (CEH). Methane isotope analysis was carried out in the life sciences mass spectrometer facility (CEH) via NERC facility funding.
The other authors of the paper, ‘Direct isotopic evidence of biogenic methane production and efflux from beneath a temperate glacier’, are: Dr Rebecca Burns, Professor Phil Barker, Dr Hugh Tuffen, Dr Zheng Zhou, Miss M Stuart, and Professor Nick Ostle, all from Lancaster University, Dr Andy Stott, Dr Niall McNamara, and Mr Simon Oakley from the Centre for Ecology & Hydrology, Prof Fiona Tweed at Staffordshire University, and Mr Aaron Chesler at the University of Maine, USA.
The Royal Society supports Dr Hugh Tuffen.