How Permafrost Thawing is Accelerating the Climate Crisis
Dr. Roger Michaelides
Spotlight: Dr. Roger Michaelides | Dept. of Earth, Environmental, and Planetary Sciences
Contributed by Sadie Brett-Chin and Guinter Dame Vogg on July 25, 2023.
The climate crisis is largely attributed to an imbalance in the planet’s carbon cycle, where carbon reserves that have been formed over millions of years, through geological and biological processes, are being rapidly released into our atmosphere due to human activities. One of the most overlooked and largely unexplored fields in this cycle is the study of permafrost, land that stays frozen for two or more years consecutively. The field still holds much to be discovered, and Dr. Roger Michaelides brings his expertise in radar science to the field of permafrost science to study different aspects of permafrost and periglacial landscapes. With a double major in physics and science of earth systems from Cornell University, his fascination with planetary science and astronomy originally led him to study Saturn’s moon, Titan, using radar imaging techniques. He was inspired by his research experience in planetary science to pursue a Ph.D. in geophysics at Stanford University, where he studied permafrost and wildfire interactions. Later, Michaelides was a postdoctoral researcher at the Colorado School of Mines. Dr. Michaelides joined the faculty of Washington University in August 2022, where he continues to study permafrost with different radar remote sensing techniques.
Even though permafrost covers only approximately 9% of the continental land surface on the planet, it contains between 25-50% of the carbon that is contained within soils on Earth. Due to warming air temperatures in the Arctic, permafrost has been subject to thaw-induced degradation, which releases large amounts of carbon dioxide and methane into our atmosphere. Michaelides uses interferometric synthetic aperture radar (InSAR), to study the thaw cycles of permafrost. InSAR is a remote sensing technique that makes use of periodic radar images of the earth’s surface collected from either satellites or aircraft. By comparing radar images collected at different times, scientists can measure how much the surface of the Earth has moved in between image acquisitions with centimeter-scale accuracy. When permafrost thaws, the ground subsides or moves downward, which can be quantified with InSAR. Much of Michaelides’ work is concentrated in the Arctic. As the air temperatures change, there are places in the Arctic where the air temperature record is increasing about four times more than the global average, making the Arctic one of the fastest-changing regions on Earth. When the air temperature is greater than the freezing point, frozen organic carbon stored in permafrost thaws and can be decomposed by bacteria in the soil. This decomposition releases carbon in the form of carbon dioxide and methane into the atmosphere. Further warming can result, causing a positive feedback loop. Michaelides describes this as a potential tipping point that has the potential to significantly impact the climate system.
Michaelides is particularly interested in investigating the interactions between permafrost and wildfires. Alaska experiences a significant wildfire season most summers, and those wildfires play very important and critical ecological roles. However, as air temperatures increase, the severity and frequency of large wildfire events are expected to increase, and this increase may significantly impact the susceptibility of permafrost to enhanced thaw and degradation. When wildfires burn vegetation, there is less vegetation to thermally insulate the ground and soil absorbs more solar radiation than usual during summer months; this promotes deepening seasonal thaw depths and can lead to permafrost degradation, and hence elevated release of greenhouse gasses into the atmosphere. During his Ph.D., Michaelides focused on the Yukon–Kuskokwim River Delta, a region in southwest Alaska that has experienced a series of wildfires from the 1950s to the 2020s. Using InSAR, Michaelides and his colleagues estimated the post-fire recovery process of permafrost and tundra landscapes by explicitly considering how the time since the wildfire occurred affected how the landscape is behaving seasonally and interannually. By sampling across space and time, they concluded that it can take as much as 60-70 years for the tundra to return to its pre-fire status, assuming that air temperatures remain stable during that time-an assumption that may not necessarily be valid.
As researchers work to better understand climate change drivers, impacts, and strategies for adaptation, Michaelides’ research to understand the role that wildfires and thawing permafrost play in the earth’s intricate climate system will be an essential piece of the puzzle. Thawing permafrost can release viruses and bacteria like anthrax that have been frozen in the ground for thousands of years-pathogens for which humans may have not built up sufficient natural immunity. Thawing permafrost will also have major implications for coastal erosion and displacement of coastal populations, many of which are indigenous communities. In some locations in the Arctic, coastal retreat rates greater than 10 meters per year have been observed, and villages like Newtok are undergoing efforts at relocation due to the impacts of rapid erosion due to permafrost thaw.
All of Dr. Michaelides’ publications can be found here
Dr. Michaelides’ personal website can be found here
Relevant Publications
Michaelides, R. J., Bryant, M. B., Siegfried, M. R., & Borsa, A. A. (2021). Quantifying surface-height change over a periglacial environment with ICESat-2 laser altimetry. Earth and Space Science, 8, e2020EA001538. https://doi.org/10.1029/2020EA001538
Michaelides, R. J., Chen, R. H., Zhao, Y., Schaefer, K., Parsekian, A. D., Sullivan, T., et al. (2021). Permafrost Dynamics Observatory—part I: Postprocessing and calibration methods of UAVSAR L-band InSAR data for seasonal subsidence estimation. Earth and Space Science, 8, e2020EA001630. https://doi.org/10.1029/2020EA001630
R. J. Michaelides, ‘Quantifying permafrost processes and soil moisture with interferometric phase and closure phase’ [PhD Thesis], 2020. https://searchworks.stanford.edu/view/13639648
R. Michaelides, K. Schaefer, H. Zebker, A. Parsekian, L. Liu, J. Chen, S. M. Natali, S. Ludwig, and S. Schaefer, “Inference of the impact of wildfire on permafrost and active layer thickness in a discontinuous permafrost region using the remotely sensed active layer thickness (ReSALT) algorithm,” Environmental Research Letters, 2018. https:// doi.org/10.1088/1748-9326/aaf932
Jingyi Chen, Yue Wu, Michael O’Connor, Meinhard B Cardenas, Kevin Schaefer, Roger Michaelides, George Kling. (2020). Active layer freeze-thaw and water storage dynamics in permafrost environments inferred from InSAR, Remote Sensing of Environment, 248. https://doi.org/10.1016/j.rse.2020.112007