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Investigating the dynamics that reshape permafrost environments

Exploring the dynamics that reshape permafrost environments

Taking measurements at the Barrow Environmental Observatory, 330 miles north of the Arctic Circle for the Next-Generation Ecosystem Experiment (NGEE-Arctic). The project aims to improve climate model predictions by studying terrestrial ecosystems in the Arctic. Credit: Roy Kaltschmidt, Lawrence Berkeley National Laboratory

When permafrost thaws, the water can flow through the ground faster, creating a complex underground flow system. Researchers at the Barrow Environmental Observatory in Alaska gained insight into this process by measuring the ground’s electrical resistance on a daily basis. The results show that vegetation and the snowpack that accumulates on the vegetation in winter regulate the temperature of the soil and the flow of water in the soil. Where snow accumulates, ground temperatures remain warmer and water and energy from snowmelt and rain can quickly flow through the ground. Where the snow cover is thin, ground temperatures are colder, preventing the flow of water.

By highlighting the link between above and below ground features and processes in the Arctic, scientists can better predict how the Arctic will relate to broader climate change. The results also show that Arctic systems are changing rapidly and that permafrost at the research team’s site could disappear within the next decade. Changes in snow distribution and rain patterns can accelerate this process.

Climate change is causing rapid changes in Arctic ecosystems, but scientists have not collected enough data to unravel complex underground processes associated with these changes. Using geophysical and in situ sensing, researchers have closed an observation gap related to thermohydrological dynamics in discontinuous permafrost systems.

Collecting data over more than two years of monitoring, researchers were able to uncover the effects of vegetation, topography and snow thickness distribution on subsurface thermohydrological properties and processes. Large snow accumulation near tall shrubs insulates the ground and provides rapid and downward heat flow, while thinner snow cover over low grasses and sedges results in surface freezing and prevents water from entering the subsoil.

The research team analyzed short-lived disturbances such as melting snow or heavy rainfall and found that lateral flow could be a driving factor in the formation of a talik, a subsurface layer in permafrost that remains unfrozen year-round. Interim measurements show that temperatures in the deep permafrost have risen by about 0.2 degrees Celsius in two years.

The results of this study, which suggest that snow-vegetation-subsurface processes are closely linked, will improve Arctic feedback predictions on climate change, including how subsurface thermohydrology affects carbon dioxide and methane fluxes.

The study is published in the Geophysical Survey Letters

Scientists find new indicators of thawing Alaska’s permafrost

More information:
S. Uhlemann et al, Geophysical monitoring shows that spatial heterogeneity in thermohydrological dynamics reshapes a transitional permafrost system, Geophysical Survey Letters (2021). DOI: 10.1029/2020GL091149

Provided by the US Department of Energy

Quote: Exploring the Dynamics Reshaping Permafrost Environments (2022, June 25) retrieved June 25, 2022 from https://phys.org/news/2022-06-dynamics-reshape-permafrost-environments.html

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