Despite making a contribution of 100 billion tonnes to global warming emissions over the next century, permafrost thaw in the North is not anticipated to cause a catastrophic, runaway feedback loop with respect to climate change, according to a new report.
“We’re still in the driver’s seat,” said Dr. David Olefeldt, a professor at the University of Alberta and one of the authors of Climate change and the permafrost carbon feedback, published last week in the online journal Nature.com.
The paper, compiled by a network of international researchers, synthesizes the existing scientific knowledge on possible impacts ongoing permafrost melt in the Arctic could have on climate change.
Though it finds the emissions released from thawing permafrost to be significant, the impact of the melt pales in comparison to the climate changes being caused by emissions from fossil fuels.
“One of the things we want to emphasize is that we don’t think the permafrost thaw can turn into a runaway feedback loop situation, where it’s self-sustaining and climate change runs amok,” Olefeldt said. “When it comes to climate change, it’s still very much up to human decisions.”
The report finds that around 10 per cent of the carbon stores in frozen permafrost will be released through warming by the end of the century, totalling around 100 billion tonnes of carbon dioxide.
In comparison, the combustion of fossil fuels is releasing around 10 billion tonnes per year alone.
Though considerably lower on the order of magnitude, Olefeldt said the impact of permafrost-related carbon emissions must be factored into current climate models being used to shape global policy on climate change. Right now, the internationally agreed upon threshold for manageable climate change allows for an increase in average global temperature of two degrees Celsius.
“There’s a certain amount of carbon dioxide we can release, and what this report is saying is that 10 per cent of that has to be allocated to permafrost soils,” Olefeldt said. “So it’s reducing the amount of carbon we can release through fossil fuels by 10 per cent.”
An uncontrollable feedback loop of emissions from permafrost melt has been a worry since scientists began noticing that warming temperatures are accelerating a microbial breakdown of organic carbon in the frozen subsurface, releasing greenhouse gases like carbon dioxide and methane to the atmosphere. This effect is most common in high-latitude regions, where temperatures have risen 0.6 degrees Celsius per decade over the last 30 years – twice as fast as the global average.
In Canada, Olefeldt said the Mackenzie Valley in the Northwest Territories and the Hudson Bay Lowlands are where large stores of carbon are most vulnerable to thawing, though the phenomenon is occurring everywhere from Fort McMurray northward. Another key area, he said, is in northern Russia along the coast.
But unlike reports of an imminent and rapid permafrost-fueled “carbon bomb,” as some worst-case scenarios have put it, Olefeldt said the thaw is likely to produce a gradual and prolonged release over time, meaning humans have time to prepare.
That said, new scientific information is constantly altering what science knows and can predict about climate change. Just last week, another article published in the Nature Climate Change journal reported that the breakdown of organic materials in warming permafrost actually generates heat, boosting decomposition in a way similar to composting and causing more melting.
“So we don’t know everything,” Olefeldt said. “Even with the projections we have in our article there are large uncertainties.”
Though unlikely to ever overshadow emissions from fossil fuels, the report notes permafrost thaw will have a significant impact not only during this century, but beyond, and thus needs to be integrated into policy decisions about climate change management.
“Each additional ton of carbon released from the permafrost region to the atmosphere will probably incur additional costs to society,” the report states.