Toward A Process Understanding of the Methane Thermodynamics Associated with Permafrost Thaw at the Arctic Continental Shelves

Arctic permafrost stores about 1,700 billion tons of organic carbon in frozen deposits. That’s twice as much carbon as what’s in the atmosphere. If just a fraction of that melts, the escaping methane would become one of the world’s largest sources of greenhouse gas and would severely impact the environment and climate.

We know that over the last 20,000-years, a quarter of the stored organic carbon in Arctic permafrost has been flooded by the rising, warm seas. But what will happen to the remaining permafrost and its organic carbon stores when warming causes further sea level rise? How much methane will be released into the ocean water and the atmosphere when the permafrost is flooded?

Answering these questions will help us understand whether the flooding and thawing of Arctic permafrost will lead to ocean acidification and stronger Arctic warming. However, collecting data in the Arctic is difficult. That means we don’t yet know enough about the Arctic carbon cycle to answer these questions.

The goal of this project is to see how computer simulations and math can help. The project will give us a clearer picture of how the temperature, soil, chemistry and microbes of the permafrost change together when it’s flooded, and what happens to the methane as it bubbles through the water. That will help us figure out the role of Arctic permafrost in the carbon cycle, ocean chemistry and climate warming, both in the past and in the future.

In addition, the project will provide interdisciplinary education experiences for undergraduate and graduate students and feature workshops to increase the number and diversity of students pursuing STEM degrees and careers. It will also give insights that will guide future drilling expeditions, improve Earth system (climate) models, and assist policy makers.

This project will investigate how flooding of the Arctic continental margin contributes to the cycle of methane into the ocean and atmosphere. Arctic permafrost is a significant natural reservoir of methane, a greenhouse gas that’s 84 times more potent than carbon dioxide over a 20-year timeframe. When sea level began rising sharply after the Last Glacial Maximum, warmer sea water (as warm as 10-15℃) flooded the Arctic and raised the temperature of the permafrost.

That significantly degraded the permafrost and caused widespread gas release along the Arctic continental shelves. However, the methane source, its current rate and magnitude, as well as future projections, have not yet been modeled and are not well constrained. This project will compile thermal, hydrological, microbial and geochemical parameters that are characteristic of the Arctic continental shelves; the research team will conduct a systematic set of one-dimensional numerical simulations to calculate the upper and lower limits of methane release following the flooding of the Arctic continental shelves; the one-dimensional results will then be scaled up to predict three-dimensional probabilistic maps of seabed microbial methane exchange, and create future projections for the U.S.

Beaufort Sea and the Laptev Sea shelves. The project will develop a systematic understanding of the coupled thermal, physical, chemical and microbial evolution of the Arctic permafrost system in response to warming. By understanding these processes, we can advance our knowledge of the role of Arctic permafrost in the carbon cycle, ocean chemistry and past and future climate warming.

The project will provide interdisciplinary training experiences for undergraduate and graduate students and develop an earth science-focused training module for a K-12 outreach program. It will support a female scientist to build her research team. In addition, the project will develop specific testable hypotheses that could guide future drilling expeditions, Earth system modeling, and policy making.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.