Wednesday, October 27, 2021

The Melting Actic

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.

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.

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.

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.

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 by 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, explained. “Already, we’re looking at irreversible changes.”

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.”

Arctic ground ‘literally collapsing’ amid abrupt thaw | Climate Crisis News | Al Jazeera

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