Rural Alaska Has a Bridge Problem as Permafrost Thaws

America’s bridges are in rough shape. Of the nearly 620,000 bridges over roads, rivers and other waterways across the U.S., more than 43,500 of them, about 7%, are considered “structurally deficient.”

In Alaska, bridges face a unique and growing set of problems as the planet warms.

Permafrost, the frozen ground beneath large parts of the state, is thawing with the changing climate, and that’s shifting the soil and everything on it. Bridges are also increasingly crucial for rural residents who can no longer trust the stability of the rivers’ ice in spring and fall.

The infrastructure bill making its way through Congress currently includes US$40 billion in new federal funds for bridgeconstruction, maintenance and repairs – the largest investment in bridges since construction of the interstate highway system started in the 1950s. In that funding is about $225 million to address 140 structurally deficient

— source | Guangqing Chi, Davin Holen, Heather Randell, Megan Mucioki, Rebecca Napolitano | Oct 13, 2021

Nullius in verba

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Massive reserves of mercury hidden in permafrost

northern permafrost soils are the largest reservoir of mercury on the planet, storing nearly twice as much mercury as all other soils, the ocean and the atmosphere combined. Warmer air temperatures due to climate change could thaw much of the existing permafrost layer in the northern hemisphere. This thawing permafrost could release a large amount of mercury that could potentially affect ecosystems around the world. Mercury accumulates in aquatic and terrestrial food chains, and has harmful neurological and reproductive effects on animals. The study found approximately 793 gigagrams, or more than 15 million gallons, of mercury is frozen in northern permafrost soil. The study also found all frozen and unfrozen soil in northern permafrost regions contains a combined 1,656 gigagrams of mercury, making it the largest known reservoir of mercury on the planet.

— source American Geophysical Union | Feb 5, 2018

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Arctic permafrost releases more CO2 than once believed

Rising global temperatures are causing frozen Arctic soil — permafrost — in the northern hemisphere to thaw and release CO2 that has been stored within it for thousands of years. The amount of carbon stored in permafrost is estimated to be four times greater than the combined amount of CO2 emitted by modern humans.

Research results from an international team, which includes a researcher from the University of Copenhagen among others, suggests that the newly discovered phenomenon will release even larger quantities of CO2 than once supposed from organic matter in permafrost — a pool of carbon previously thought to be bound tightly and safely sequestered by iron.

The amount of stored carbon that is bound to iron and gets converted to CO2 when released is estimated to be somewhere between two and five times the amount of carbon released annually through anthropogenic fossil fuel emissions.

Iron doesn’t bind organic carbon after all

Researchers have long been aware that microorganisms play a key role in the release of CO2 as permafrost melts. Microorganisms activated as soil thaws convert dead plants and other organic material into greenhouse gases like methane, nitrous oxide and carbon dioxide.

What is new, is that the mineral iron was believed to bind carbon even as permafrost thawed. The new

— source University of Copenhagen – Faculty of Science | Feb 9, 2021

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Locked greenhouse gases in submarine permafrost are emerging

Something lurks beneath the Arctic Ocean. While it’s not a monster, it has largely remained a mystery.

According to 25 international researchers who collaborated on a first-of-its-kind study, frozen land beneath rising sea levels currently traps 60 billion tons of methane and 560 billion tons of organic carbon. Little is known about the frozen sediment and soil — called submarine permafrost — even as it slowly thaws and releases methane and carbon that could have significant impacts on climate.

To put into perspective the amount of greenhouse gases in submarine permafrost, humans have released about 500 billion tons of carbon into the atmosphere since the Industrial Revolution, said Sandia National Laboratories geosciences engineer Jennifer Frederick, one of the authors on the study published in IOP Publishing journal Environmental Research Letters.

— source DOE/Sandia National Laboratories | Feb 10, 2021

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The irreversible emissions of a permafrost ‘tipping point’

Across vast swaths of the northern hemisphere’s higher reaches, frozen ground holds billions of tonnes of carbon.

As global temperatures rise, this “permafrost” land is at increasing risk of thawing out, potentially releasing its long-held carbon into the atmosphere.

Abrupt permafrost thaw is one of the most frequently discussed “tipping points” that could be crossed in a warming world. However, research suggests that, while this thawing is already underway, it can be slowed with climate change mitigation.

Tipping points

This article is part of a week-long special series on “tipping points”, where a changing climate could push parts of the Earth system into abrupt or irreversible change

— source skepticalscience.com | Christina Schädel | 7 Apr 2020

Nullius in verba

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