Scientists are increasingly warning that the melting Arctic could push the planet into a vicious cycle of uncontrolled heating as vast stores of carbon in thawing ground release powerful greenhouse gases.
For thousands of years, permafrost – ground that is frozen for two or more years in a row – has kept dead plant and animal matter locked in the deep-freeze beneath the tundra. These ancient remnants total up to an estimated 1,600 billion tonnes of organic carbon, almost twice as much as currently found in the Earth’s atmosphere.
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Covering a quarter of the Northern Hemisphere, this frozen vault is being thawed by rising temperatures, extensive wildfires and unprecedented heatwaves in Siberia and other far-northern regions. In turn, that is transforming the carbon sink of the Arctic into a source of greenhouse gases.
Among those gases is methane, a gas up to 34 times more potent than carbon dioxide (CO2) at trapping heat in Earth’s atmosphere during a 100-year period. Across 20 years, it can be 86 times more potent. Then there’s nitrous oxide – its warming potential roughly 300 times more than CO2 across a 100-year timescale.
That is creating a dangerous feedback loop – one in which human activities such as burning fossil fuels and farming livestock heat up the atmosphere, prompting permafrost to thaw and release additional greenhouse gases.
That causes further heating, further thawing and further emissions, threatening to bring about the worst impacts of climate changes far faster than expected.
“This is likely to accelerate because of the scale of the warming we’re seeing in the Arctic,” Rachael Treharne, an Arctic ecologist at Woodwell Climate Research Center, who studies the impact of thawing permafrost and wildfires on climate change, told Al Jazeera.
“Already, we’re looking at irreversible changes.”
The warnings come ahead of the United Nations Climate Change Conference, or COP26, to be that is seen by many as the last chance to avert a global environmental catastrophe.
Plans to reduce carbon emissions could be thrashed out at the conference, which will be held in Glasgow, Scotland from October 31 until November 12.
‘We cannot control nature’
The Arctic has already heated to more than 2C (3.8F) above its pre-industrial average, with temperatures tipped to rise further.
These northern latitudes are heating at more than twice the rate of the global average due to the rapid loss of sea ice, replacing a highly reflective white surface with the sea’s highly heat-absorbing blue-black.
Scientists have been shocked that higher temperatures conducive to permafrost thawing are occurring roughly 70 years ahead of projections.
Permafrost’s polluting potential begins when the damper, warmer conditions of thawing ground jumpstart microbes to produce carbon dioxide or methane as they feast on decomposing organic matter in boggy, once-hard soil.
Thawing bedrock compounds this problem. As temperatures rise and pressures change, frozen deposits of naturally occurring methane and other hydrocarbons inside the permafrost turn into gas, which may be released through cracks into the atmosphere.
“We can more or less control the burning of fossil fuels through political decisions and economic regulations,” said Dmitry Zastrozhnov, a lecturer and geologist at the Institute of Earth Sciences at St Petersburg State University who is studying the release of methane from Siberian limestone areas.
“But we cannot ask permafrost to stop releasing methane. We cannot control nature.”
Scientists have also detected the accelerated release of these potent greenhouse gases in the Arctic Ocean off northern Russia’s Siberian coast.
Known as hydrates, crystals made of methane gas molecules trapped between solid water molecules collapse as temperatures rise. These then vent into the atmosphere after reaching the surface as bubbles.
The increasing frequency and severity of Arctic and boreal wildfires emit large amounts of carbon – not only from combustion but also by subjecting permafrost to further thaw.
Last year, these unprecedented blazes released 35 percent more CO2 than in 2019, which itself was the previous record high for Arctic wildfire emissions.
Those fires came amid a record-breaking Siberian heatwave as temperatures peaked at 38C (104F) – the highest ever recorded temperature in the Arctic Circle – in a town that, more than a century earlier, had recorded the Northern Hemisphere’s coldest ever temperature. At the same time, Arctic sea ice shrunk to its second-lowest level on record.
These problems are exacerbated by a range of processes known collectively as “abrupt thaw”, causing landscapes to scar the Arctic landscape.
The thawing of ice-dense permafrost can trigger gradual subsidence or even extensive ground collapse, exposing deep permafrost to further thawing and releasing yet more carbon into the atmosphere.
Discovering the rate and amount of permafrost thaw is key to understanding how quickly and substantially it is necessary to cut human-caused emissions. One paper published in 2018 found that abrupt thawing boosts the release of ancient carbon by up to 190 percent compared with gradual thawing.
“We don’t have to wait 200 or 300 years to get these large releases of permafrost carbon,” said Katey Walter Anthony at the University of Alaska who led the study. “Within my lifetime, my children’s lifetime, it should be ramping up.”
Earlier this year, researchers warned that these gas-emitting processes are not fully accounted for in global projections – meaning that those projections are likely too low, making it harder for the world to curb climate change.
That greatly reduces the amount of greenhouse gases that humans can emit to limit global warming to 1.5C (2.7F) beyond pre-industrial levels, a key target of the 2015 Paris Agreement on climate.
“There is an urgent need to incorporate the latest science on carbon emissions from permafrost thaw and northern wildfires,” the study’s authors said.
The problem is that these are extremely complex processes, occurring in one of the world’s largest and most remote regions. Better scrutiny and collaboration are key.
“We need to invest more in monitoring systems and combine all the efforts from different disciplines to better understand and model it,” said Zastrozhnov, the geologist.
Besides the global impact, four million people live across the Arctic. These local communities are at the sharp end of a changing landscape, facing more landslides, disrupted watercourses and damaged infrastructure.
Mercury leaches from melting permafrost into rivers and accumulates in the food chain. Oil depots leak as the earth gives way. Communities endure displacement while havoc is wrought on traditional food sources – key to the wellbeing of Indigenous people who have co-existed with this unique habitat for thousands of years.
“We are seeing a humanitarian crisis,” said Treharne. “The ground is literally collapsing under their feet. We are underestimating the urgency of what we need to do.”
Despite the promise of carbon-capture facilities that remove emissions from the atmosphere – and even the re-wilding of Ice Age-era ecosystems to slow the thaw – experts said one solution beats all others.
“Thawing permafrost is like a massive truck that’s gaining momentum – and it’s got a braking distance,” Treharne said.
“Even if we reduce warming, permafrost is still going to be responding to that peak temperature and pumping out carbon. If we want to minimise carbon emissions from permafrost, we have to cut global emissions now.”