In the vast landscape of eastern Siberia there is a massive hole in the ground known as the “doorway to the underworld” triggered from climate change in the recent decades. The permafrost ground near the Yana River Basin has been warming lately, causing large scale changes in the local topography and ecology.

The tadpole-shaped crater, called the Batagaika crater, is known as a “megaslump” and is related to karsting triggered through permafrost melting. Currently, the crater measures 0.6 miles long and 282 feet deep. However, the crater’s growth has increased recently prompting locals to nickname it the “doorway to the underworld” and to avoid the area.

Permafrost is ground which remains at or below freezing temperatures for more than two years. This is common in the high latitudes of Siberia where average yearly temperatures prevent warming of the ground to above freezing. Pore spaces within the soil contains trapped water, which in the case of northern latitudes can be frozen in place for thousands of years.

Recent accelerated melting of permafrost is linked to climate change and the increase in average global temperatures for the past decades. Permafrost acts to preserve the sediment, dead plant and animal material within soil and bury it deeply. However, upon melting of permafrost, bacteria are given a pathway to break down vast amounts of organic materially previously inaccessible.

This acts to increase residual methane and carbon dioxide emissions from bacteria decomposition in permafrost melting areas. This perpetuates a positive feedback loop, whereby increasing greenhouse gas emissions increase global temperatures, which in turn melts more permafrost, allows for more organic matter decay and additional CO2 and methane emissions. The presence of well-known global and ecosystem wide positive feedback loops are a foundation of why scientists see Earth as having tipping points. Tipping points trigger run-away positive feedback loops that rapidly change global systems and have been studied extensively in everything from ecology to astrophysics.

    

The Batagaika crater has exposed the subsurface that was previously frozen, allowing scientists to look at the equivalent of roughly 200,000 years of Earth’s climate in the sediment record. These results were recently published in the journal Quaternary Research.

Age dating the sediment exposed by the crater as well as a number of inorganic and organic isotopes will allow geologists to piece together the climate record of this region of Siberia. This will include many glacial to interglacial periods and allow better understanding of how Siberia responds to global cooling (ice ages) and warming (similar to today).

The crater began to form in the 1960s as a result of deforestation which eliminated tree shade on the ground during the warmer summer months. Local vegetative shading and transpiration helped protect the ground during warm days, but with deforestation, there is little to insulate the ground from melting.

    

Gradually, over decades the ground’s permafrost began to melt and as it melted the sediment went from being supported by rigid ice to lubricated by liquid water. This causes compaction, shifting of vertical and horizontal stresses and ultimately the massive craters we see today.

The crater has been monitored for decades via satellite imagery and has grown in size an average of 33 feet per year. Some years, that increases to about 100 feet per year, in which the steep headwall destabilizes and collapses.

Measuring the sediment record at the crater will allow temperature and chronological records to be compared with ice sheets at the poles to regionally characterize warming and cooling periods. The research group is specifically looking at examples like 125,000 years ago when the global interglacial temperature was several degrees warmer than it is today. Understanding how Siberia responded to the warmer temperatures in the past will provide clues as to how Siberia will respond to current warming trends. If the past is a picture into the future, Siberia will see significant melting of permafrost, creation of craters and basins and eventual formation of pocket lakes.