Coastal permafrost more susceptible to climate change than previously thought

October 23, 2020

If you flew from the sea towards the land in the north slope of Alaska, you would cross from the water, over a narrow beach, and then to the tundra. From the air, that tundra would look like a landscape of room-sized polygonal shapes. Those shapes are the surface manifestations of the ice in the frozen ground below, a solidified earth known as permafrost.

Scientists long believed the solid permafrost extended offshore: from the tundra, below that narrow beach and below the seafloor declining at a gentle slope. They viewed that permafrost like solid brick, locking the subsurface--and the vast amounts of carbon it holds--in place.

But new research led by Micaela Pedrazas, who earned her masters at The University of Texas at Austin Jackson School of Geosciences working with Professor Bayani Cardenas, has upended that paradigm. They found permafrost to be mostly absent throughout the shallow seafloor along a coastal field site in northeastern Alaska. That means carbon can be released from coastline sources much more easily than previously thought.

The study was published in Science Advances on Oct. 23 with coauthors from the Jackson School and UT's Marine Science Institute.

Using a geophysical technique called electrical resistivity imaging, the researchers mapped the subsurface beneath Kaktovik Lagoon along the northeastern coast of Alaska over the course of three years.

The results were unexpected. The beach and seafloor were entirely ice-free down to at least 65 feet. On the tundra itself, ice-rich permafrost was detected in the top 16 feet, but below that, the subsurface their imaging mapped was also ice-free.

"This leads to a new conceptual model," Pedrazas said.

Permafrost is found in cold climates that remain frozen during the course of the year. Scientists have been tracking the impact of a warming climate on permafrost because as it melts, permafrost releases its stores of frozen carbon into the atmosphere as methane and carbon dioxide, contributing to climate change.

Permafrost studies have almost exclusively focused on the region beneath the tundra. Because it's not easy to work in such remote locations and under harsh weather conditions, the transition from sea to shore has been largely ignored.

"This study tells us that the coastline is much more complicated than we thought," said co-author Jim McClelland from UT's Marine Science Institute. "It opens up the possibility for routes of water exchange that we weren't thinking about."

Besides global considerations, the work has local impacts. The communities along the coast, most of whom are Inupiat, live on the permafrost. As the permafrost thaws, it accelerates coastal erosion, which carves away at the land on which homes and infrastructure stand. In the Kaktovik region, erosion can be as great as 13 feet per year.

"Their cultural heritage and their welfare is integrated and intricately linked to their environment," Cardenas said. "There's an immediate need to understand what's happening in these lagoons."

The new paradigm requires reimagining the coastal Arctic ecosystem as well. Liquid groundwater means that carbon and nutrients can move between the tundra and the lagoon. It also means that saltwater can move beneath the tundra, potentially affecting freshwater sources.

Paul Overduin, who wasn't involved in the research, but who studies permafrost at Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, said that this work is the first step in understanding permafrost's transition from sea to shore.

"As is often the case, when we start looking at something people don't know much about, you open up a whole bunch of questions that needed to be looked at," he said. "That's what's really exciting here."
The research was funded by the Geology Foundation at The University of Texas at Austin and the National Science Foundation through the Beaufort Lagoon Ecosystems LTER, the Geological Society of America and the Ivanhoe Foundation. The Kaktovik Inupiat Corporation and the U. S. Fish and Wildlife Service also provided permissions and support.

University of Texas at Austin

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to