By comparing high-resolution aerial photography and satellite images of frozen Arctic tundra over six decades, an environmental scientist from San Antonio’s Southwest Research Institute has helped an international team of experts document an alarming increase in the thawing of Earth’s critical layer of permafrost.

That layer of continuously frozen soil and rock covers millions of square miles in northern Canada, Russia and Alaska, where the lengthy study took place. The recent thawing of permafrost captivates climate scientists because it holds oceans of carbon dioxide and methane gas, which, when released, accelerate global warming.

Using a trove of declassified military satellite photography taken from 1948 to 2012, the research institute’s Marius Necsoiu matched identical patches of land at 10 separate locations across the Arctic and was able to detect drying and subsidence of the permafrost that shocked many of the 19 scientists involved in the study.

“Most of the sites are just in the initial stages of degradation,” said Necsoiu, a native of Romania who has been with SwRI 15 years. “But the degradation has occurred so quickly, in less than a decade, and really just after a few very warm summers.”

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Necsoiu used still satellite photographs, some taken from as high as 600 miles, that were so precise he could tell changes in the tundra hydrology “dynamics” that amounted to mere centimeters or millimeters over many decades. His “remote sensing” computer-based work in San Antonio aided on-the-ground scientists from Russia, Germany, Canada, England and, primarily, Alaska, who often did their field work in temperatures of 5-10 degrees below zero Fahrenheit.

“I love this work. I’ve done this since I was little,” said Necsoiu, as he sat in a SwRI conference room zooming in on a satellite photo that showed a once-moist, seamless carpet of tundra dried and cracked like an old baseball glove left baking in the sun.

Among the most obvious changes in the Arctic, where the surface air has warmed about five degrees in the past century — that’s more than twice the global average — were large channels of water several feet in width that have formed from the underground melting of ice. Rather than re-freezing for the winter and remaining trapped inland, as they have for millennia, these newly formed channels now drain the spongy, lichen-covered land and take its pristine water off to the ocean.

“If this thaw continues,” said the study’s lead researcher, Anna Liljedahl, a permafrost hydrologist at the University of Alaska Fairbanks, “we could lose four meters of elevation (from subsidence) over our lifetime, bringing the ocean over Barrow, Alaska, a town of 4,000.”

Echoing Necsoiu, Liljedahl said she was most alarmed by the speed of the thaw. “We’ve documented one meter of subsidence in some places in less than one decade,” she said. “We’ve not seen that before. This is the tipping point for the hydrology.”

Liljedahl said while some of the water seen running in the channels in summer is just seasonal snow runoff, some of the deep blue rivulets no doubt contain water that has thawed after being frozen for thousands of years, perhaps since the Bronze Age.

River erosion and gold mining in Alaska have often exposed the remains of now-extinct animals from the last great ice age 100,000 to 10,000 years ago, when woolly mammoths and mastodons roamed the tundra.

Thawing permafrost does more than scare scientists.

When the land sinks it often ripples or ruins roads, wobbles houses and imperils infrastructure such as the 800-mile Trans-Alaska Pipeline, 420 miles of which must be elevated above the permafrost so the heated petroleum (up to 112 degrees) doesn’t promote thawing. If the Arctic, which only gets a few inches of precipitation a year, begins to dry further due to thawing permafrost, the loss of vegetation on the surface will quickly disrupt animal habitat, and the elimination of shallow lakes and ponds could doom millions of migratory birds who travel some 20,000 miles to get there.

Some scientists believe that massive releases of methane gas at the Arctic could cause the rise of inland temperatures as far as 900 miles away.

As for how the study, which was published in Nature Geoscience, will be viewed by those who believe climate warming is a random and temporary event, Liljedahl termed it “one more piece of the puzzle that will hopefully help those people decide climate warming is real.”

Thawing arctic permafrost has alarmed scientists for quite some time. A 2013 study in Nature estimated that the reservoir of methane trapped beneath permafrost on just the East Siberian Arctic Shelf alone would total some 50 billion tons.

Vladimir Romanovsky, also from the University of Alaska Fairbanks, has said: “We have at least theoretical control of human emissions, but (with) thawing permafrost there is no way to control it or stop it.”

Steven Chu, who won the Nobel Prize in physics in 1997, said that once thawing of the permafrost begins, “the amount of greenhouses gases released will dwarf the amount that humans are putting into the air now. We don’t know exactly at what temperature this will occur, but … we cannot go there.”

bselcraig@express-news.net