Below where life develops is the layer of frozen soil, which we know as permafrost . A portion of permanently frozen soil with insufficient water to form visible ice crystals. This is not ice, but frozen ground.
Arctic permafrost needs to stay frozen. In many places it has been frozen for tens of thousands of years, blocking greenhouse gases and ancient diseases buried deep inside.
Sadly, our planet’s changing climate is eroding permafrost around the world. And now, NASA-funded research has confirmed that the gradual thawing of Arctic permafrost is being accelerated dramatically by a natural phenomenon known as thermokarst lakes.
Arctic lakes, which form when surface ice melts and the ground collapses, could thaw underground permafrost much faster than scientists thought possible, reveals the study published in the journal Nature.
The deep layers of permanently frozen soil that underlie much of the Arctic hide massive stores of organic carbon, in the form of thousands of years of trapped plant matter and even animal carcasses. As the soil gradually melts, these buried organisms will decompose and release greenhouse gases, carbon dioxide, and methane into the atmosphere, which in turn can lead to even greater warming . It was thought that this would not happen until after the year 2100.
“Lakes will release carbon from permafrost long before it melts on land,” says Katey Walter Anthony, an ecologist and biogeochemist at the University of Alaska Fairbanks.
Scientists have been studying so-called thermokarst lakes, which are created when ice-rich soil melts, causing the land below to collapse and form a well, where the melted water collects. Termokarst lakes look like biscuits that have been bitten around their edges, experts explain, because liquid water ‘nibbles’ the surrounding frozen margins, causing the lake to expand.
Lakes can also be up to 100 feet deep, and if the water doesn’t freeze to the bottom in winter, the heat in the liquid water causes the permafrost beneath that lake to melt.
Thus, “what used to be soil frozen with organic carbon, thaws, and that thawed soil releases this organic matter to microbes that decompose it and produce carbon dioxide and methane”, comments Walter Anthony, co-author of the work.
The researchers wanted to quantify how much methane (the main component of the gas that bubbles in the lakes) these lakes are emitting today, and what is the forecast of emissions for the future. The team used a combination of computer models and measurements taken from fieldwork in Alaska, Canada and Siberia to map the growth and emissions of the thermokarst lakes.
According to the results, the lakes would double previous estimates of the warming of the greenhouse effect caused by permafrost.
Although the Termokarst lakes are currently not included in global climate change models because they are small and dispersed, the team says this new research shows how important it is to include them.
Human fossil fuel emissions remain the main source of greenhouse gas emissions, but it is clear that monitoring these lakes is extremely important.
Reference: 21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes. Katey Walter Anthony, Thomas Schneider von Deimling, Ingmar Nitze, Steve Frolking, Abraham Emond, Ronald Daanen, Peter Anthony, Prajna Lindgren, Benjamin Jones & Guido Grosse. Nature Communications (2018)
