A new study from the Moscow Institute of Physics and Technology (MIPT) suggests that rapid Arctic warming is linked to a series of great earthquakes. Greenhouse gas emissions associated with human activities are driving temperatures up on a global scale, but this does not explain abrupt temperature spikes that have been periodically observed in the Arctic.
One of the main factors involved in Arctic warming is the release of methane from thawing permafrost. In the time since record-keeping began, the region has experienced two periods of abrupt warming: in the 1920s and 1930s, and then from 1980 to present day.
Study author Leopold Lobkovsky is a member of the Russian Academy of Sciences and the head of the MIPT Laboratory for Geophysical Research of the Arctic and Continental Margins of the World Ocean. In his report, Lobkovsky theorizes that unexplained temperature changes in the Arctic could have been triggered by geodynamic factors. In particular, he points to a series of great earthquakes in the Aleutian Arc, which is the closest seismically active area to the Arctic.
To test his theory, Lobkovsky first investigated whether the dates of the great earthquakes coincided with temperature spikes. Based on historical data, he found that the Aleutian Arc was the site of two series of earthquakes in the 20th century. Each of the events was followed by an abrupt rise in temperature about 15 to 20 years later.
Next, Lobkovsky needed to determine how the lithospheric disturbances may have spread over more than 1,240 miles from the Aleutian Islands to the Arctic shelf region.
A model of lithospheric excitation dynamics predicted that the propagation of so-called tectonic waves should travel at about 100 kilometers, or 62 miles, per year. This explains the delay between each earthquake series and the subsequent increase in Arctic temperatures 15 to 20 years later.
Finally, Lobkovsky set out to understand how these disturbances may intensify methane emissions. He concluded that the deformation waves arriving in the shelf zone cause minor additional stresses in the lithosphere, which are sufficient to disrupt the internal structure of the permafrost. This releases heat-trapping methane into atmosphere, leading to local climate warming.
“There is a clear correlation between the great earthquakes in the Aleutian Arc and the phases of climate warming. A mechanism exists for physically transmitting the stresses in the lithosphere at the appropriate velocities. And these added stresses are capable of destroying metastable gas hydrates and permafrost, releasing methane.”
“Each of the three components in this scheme is logical and lends itself to mathematical and physical explanation. Importantly, it explains a known fact – the abrupt rise in temperature anomalies in the Arctic – which remained unaccounted for by the previous models.”
According to Lobkovsky, his model will benefit from discussion and will likely be improved, and further research is needed in order to confirm or rule out the link between seismic activity and abrupt Arctic warming.
The study is published in the journal Geosciences.
By Chrissy Sexton, Earth.com Staff Writer