Fifty years ago, this Alaskan site was a frozen spruce forest. Today, it is a 10-foot-deep lake.
Today, things are rather different: the forest is gone.
The ground collapsed into a thermokarst lake that is now boiling with methane bubbles.
NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE) confirms this lake formed in just 50 years due to abrupt thaw.
What concerns them most is not the water itself; it’s the gas escaping from below.
Big Trail Lake: How the Arctic’s newest methane fountain emerged
Researchers first noticed unusual changes in interior Alaska through older aerial photographs and satellite comparisons.
Large stretches of land no longer matched earlier surveys.
Ground that once remained frozen year-round had started sinking unevenly.
Pools of water formed first. Then entire sections widened into lakes.
Scientists studying the area realized thawing permafrost was reshaping the terrain from below.
Permafrost here contains 50% to 80% ice. As it melts, the soil loses volume and sinks into a basin.
That process created expanding basins that trapped rainwater and melted snow. The lakes continued growing after formation.
Researchers also noticed another pattern.
Some newly formed lakes released unusually large amounts of gas bubbles through the surface.
Ebullition (bubbling) is most violent at the ‘thaw bulb’ edges where the lake expands into new frozen soil.
Scientists suspected the collapsing ground was exposing something ancient beneath the surface.
Exhausted vs. explosive: How the chemistry of young Arctic lakes remains hidden
Researchers began drilling into sediments beneath several lakes in Alaska.
The material below the water looked very different from ordinary lake mud.
Most of it came from frozen soil that only recently thawed out. Which mattered, because frozen ground stores vast amounts of organic material.
Roots, mosses, dead plants, and buried carbon can remain trapped for thousands of years.
Once thawed, microscopic organisms begin a feeding frenzy.
Microbes consume 40,000-year-old Pleistocene carbon, releasing methane—a gas 80 times more potent than CO2 over 20 years.
The microbes break down the carbon and release gases during decomposition.
Then another clue appeared: the youngest lakes often produced the strongest methane emissions.
Older lakes behaved differently.
Scientists think many older systems had already exhausted much of their easily decomposed organic matter centuries earlier.
Younger lakes still contained fresh thawing sediments rich in carbon.
That helps explain why bubbling intensified near shorelines.
Researchers also found evidence that thawing ground may create new underground pathways.
Those that allow trapped gases to rise more easily. Which could reshape the Alaskan landscape entirely.
NASA has detailed what is happening in Alaska.
Sentinel-2 satellites show these lakes are expanding across the Arctic at unprecedented rates.
A report by Copernicus says Sentinel-2 satellites show these lakes are expanding across the Arctic at unprecedented rates.
40,000 years in the making: The ‘instant’ lake venting ancient methane
The focal point of this climate shift is Big Trail Lake, a ‘young’ thermokarst feature in Goldstream Valley, Alaska.
Scientists say it barely existed in its current form around 50 years ago.
Today, it has become Alaska’s exemplar of a rapidly expanding thermokarst lake.
The bubbles are pure methane.
This occurs because newly thawed microbes are ‘eating’ yedoma—organic-rich soil frozen since the Ice Age.
For thousands of years, frozen ground hid ancient carbon. Once thawed, microbes began decomposing that material and releasing methane into the atmosphere.
Researchers say younger lakes like Big Trail can become especially powerful methane hotspots.
Because freshly thawed sediments still contain enormous amounts of untouched organic matter.
That process can feed itself.
The permafrost time bomb: Alaska’s new 40,000-year-old greenhouse gas factory
Water absorbs heat far more efficiently than frozen soil.
This creates a feedback loop. Water retains heat, deepening the ‘talik’ (unfrozen ground) and unlocking deeper carbon reserves.
And expose even more ancient carbon to decomposition.
Scientists now believe similar lakes could become increasingly important methane sources across the Arctic during this century.
Big Trail Lake shows how quickly frozen landscapes can transform.
A forested stretch became open water within decades.
Big Trail Lake is now a chimney, venting greenhouse gases trapped for 40 millennia into our modern atmosphere.