Previous studies of ice cores from Greenland and Antarctica have shown that when global climates warmed between 14,000 and 11,500 years ago, levels of methane in the atmosphere increased significantly. There was also an unidentified northern source of the gas at that time.
According to new research published in the latest edition of the journal Science (26 October), methane bubbling from Arctic lakes could have been responsible for up to 87 per cent of this northern source. The findings could help climate modellers to assess how warming affects atmospheric levels of methane, a potent greenhouse gas.
Previous hypotheses suggested that the increase came from gas hydrates or wetlands. The new study's findings indicate that methane bubbling from thermokarst lakes, which are formed when permafrost thaws rapidly, is likely to be a third and major source.
'Our research focused on areas of Siberia and Alaska which, during the last ice age, were dry landscapes underlain by deep permafrost,' commented co-author Professor Mary Edwards of the University of Southampton's School of Geography. 'As the climate warmed, the permafrost thawed, forming thermokarst lakes. When the permafrost around and under the lakes thawed, it would have released organic material into the lakes - primarily dead plant material - which would be a good energy source for methane-producing bacteria. Under such conditions, carbon which had been locked in the ground for thousands of years could rapidly be converted into potent greenhouse gases: methane and carbon dioxide.'
The group's calculations suggest that the lakes contributed 33 to 87 per cent of the methane increase from northern sources. The team examined lakes in Siberia and northern Alaska that currently release methane. They gathered samples of permafrost and thawed them in the laboratory to measure the levels of methane that permafrost soil can produce immediately after thawing. Using geological data they were able to reconstruct the pattern of lake formation since the end of the last ice age.
'Thermokarst lake formation is a source of atmospheric methane today, but it was even more important during the warming that took place at the end of the ice age,' continues Professor Edwards. 'It is possible that, with global warming, large releases from these lakes may occur again in the future.'
Sarah Watts | alfa
Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation
Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences