The frozen ground that covers a sixth of the planet is thawing due to climate change, releasing trapped carbon and the DNA of long-forgotten diseases.
Dr Guido Grosse, who heads the PETA-CARB project from the Alfred Wegener Institute in Potsdam, Germany, has been studying the Arctic for fourteen years to find out how the frozen ground, known as the permafrost, is reacting to an environment that is getting hotter all the time.
The samples he has drilled out – in regions so remote that they cannot be accessed without a helicopter or a snow mobile – leave him in no doubt that the thawing of the earth’s permafrost is accelerating. Locally, this is damaging infrastructure and wildlife populations. But what is more worrying to environmental scientists is the vast sink of carbon lying frozen beneath its surface.
‘Permafrost can be seen as a freezer,’ said Dr Grosse. ‘You open it and the organic material inside begins to rot.’ The carbon that is released from putrefaction ends up in the atmosphere, adding to greenhouse gas concentrations and further aggravating global warming. ‘We are facing the possibility of temperatures rising faster than what was quantified in the United Nations Intergovernmental Panel on Climate Change (IPCC) reports,’ he said.
The amount of carbon locked underground could represent twice the amount currently held in the atmosphere. But no-one knows how much of the permafrost is likely to thaw. In regions where temperatures are just below freezing point, the upper few metres of soil are vulnerable. In colder ones, deeper and older carbon sinks are thawing around lakes and rapidly eroding coasts. ‘We need to know how much carbon is at stake to understand how it will affect the climate,’ said Dr Grosse.
‘This is the first time in the planet’s history that a life form on its surface is capable of understanding or changing its climate.’
Professor Terry Callaghan, the University of Sheffield, UK
Data series from ground and satellite monitoring now stretch back far enough to identify an acceleration in permafrost thawing. A network of permafrost monitoring stations across the northern hemisphere show that the warming of the permafrost that started 20 to 30 years ago is continuing, with colder regions warming faster than regions where temperatures are close to 0 degrees Celsius.
Professor Terry Callaghan, head of INTERACT, a network of Arctic observation stations that is working to build capacity for monitoring the European Arctic, said that global collaboration has been crucial in advancing understanding. ‘Twenty years ago, the fall of the Iron Curtain made it possible to bring together for the first time pan-Arctic observations,’ he said. Today he coordinates a network of more than 60 research stations across three continents whose work cuts across international borders and scientific disciplines.
Dr Stefan Hagemann leads the terrestrial hydrology group at the Max Planck Institute for Meteorology in Hamburg, Germany. His permafrost modelling work supports the EU-funded PAGE21 project, which is working with computer modellers to evaluate how the permafrost will change due to global warming. ‘The response of permafrost to global warming is fantastically complex. To understand it, we need a synergy between remote imaging, field work and computer models,’ he said.
Experts from a range of disciplines assess the data and offer explanations. Computer modellers incorporate their hypotheses into their algorithms. If the simulation fits the data, Dr Hagemann feels a step closer to success. ‘Piece by piece, we are making the models more realistic and improving the precision of our predictions.’
Interactions between earth scientists and biologists have led to groundbreaking results in other areas of permafrost research. The PERMATHREAT project is investigating the health hazards of the thawing of carbon that has been frozen for thousands of years.
A sample of permafrost from Zackenberg, Northeast Greenland, where the permafrost is likely to thaw. © Bo Elberling, CENPERM (Center for Permafrost), Denmark
‘Permafrost contains DNA sequences of diseases from 500 000 years ago,’ said Uffe Wilken, from the Center for GeoGenetics in Copenhagen, Denmark. ‘Living bacteria today could incorporate these genes and spread pandemics for which present day organisms have lost immunity.’
The project has discovered the DNA of viruses as well as diseases, and the risk is that this DNA could combine with the DNA of a living bacteria or virus. So far, however, the project has seen no evidence of this happening.
His team's biggest breakthrough was identifying the genetic remains of ancient plants and woolly mammoths in permafrost dating back 20 000 years. Because genes can remain intact longer than bones, the results have provided palaeontologists with precious clues to migration and extinction events that took place as far back as the Pleistocene epoch.
Whether through releasing the DNA of frozen diseases, or flooding the atmosphere with carbon, the thawing of the permafrost represents a threat that humanity has to solve. ‘The world is at a tipping point,’ said Prof. Callaghan. ‘This is the first time in the planet’s history that a life form on its surface is capable of understanding or changing its climate. But we are still animals when it comes to changing our own behaviour. Our science has evolved rapidly, now we hope our governments will act on it.’
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