BER launches Environmental System Science Program. Visit our new website under construction!

U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


Modeling Climate Change Impacts on an Arctic Polygonal Tundra: Rates of Permafrost Thaw Depend on Changes in Vegetation and Drainage
Published: March 29, 2019
Posted: October 22, 2019

Accounting for 21st century polygonal tundra vegetation changes, and consequent effects on surface energy budgets, slows increases in active-layer deepening.

The Science
University of Alberta and Berkeley Lab researchers used a mechanistic three-dimensional (3D) ecosystem model (ecosys) to project how vegetation cover changes in polygonal tundra will interact with soil temperatures and active-layer dynamics (Grant et al. 2019). The model was shown to very accurately match a wide range of Next-Generation Ecosystem Experiments (NGEE)–Arctic observations at the Utqiagvik, Alaska, site. Vegetation and landscape-scale hydrology strongly affect surface energy budgets and thereby active-layer deepening, implying that land models must accurately represent these processes in 21st century simulations.

The Impact
Current land models applied for large-scale assessments of permafrost dynamics have poorly represented many of the processes known to affect these dynamics. In this study, the research team used a mechanistic 3D model to explore the roles that vegetation changes and landscape-scale hydrology over the coming decades will have on soil thermal dynamics. Research results point toward the importance of representing vegetation dynamics (e.g., density and composition) and hydrology at relevant spatial scales, and that doing so will result in smaller changes to soil temperatures and active-layer deepening.

Summary
Model projections of permafrost thaw during the next century diverge widely. This study used ecosys to examine how climate change will affect permafrost thaw in a polygonal tundra at Utqiagvik (formerly Barrow), Alaska. The model was tested against observed diurnal and seasonal variation in energy exchange, soil heat flux, soil temperature (Ts) and active-layer depth (ALD), and interannual variation in observed ALD from 1991 to 2015. During Representative Concentration Pathway (RCP) 8.5 scenario climate change from 2015 to 2085, increases in air temperature and precipitation altered energy exchange by increasing the leaf area index (LAI) of dominant sedge relative to that of moss. Increased carbon dioxide concentrations and sedge LAI imposed greater stomatal control of transpiration and reduced soil heat fluxes, slowing soil warming, limiting increases in evapotranspiration, and thereby causing gradual soil wetting. Larger landscape drainage slowed ALD increases. The predicted rates are closer to those derived from current studies of warming impacts in the region, but were smaller than those of earlier modeling studies, primarily because they did not account for vegetation changes. Therefore, accounting for climate change effects on vegetation density and composition, and consequent effects on surface energy budgets, will cause slower increases in active-layer deepening over the 21st century.

Contacts
BER Program Manager
Daniel Stover
U.S. Department of Energy Office of Science, Office of Biological and Environmental Research
Climate and Environmental Sciences Division (SC-23.1)
Terrestrial Ecosystem Science
daniel.stover@science.doe.gov

Principal Investigator
William J. Riley
Lawrence Berkeley National Laboratory
Berkeley, CA 94720
wjriley@lbl.gov

Funding
This research was supported by the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science, under Contract No. DE-AC02-05CH11231 as part of the Next-Generation Ecosystem Experiments (NGEE)–Arctic project.

Publications
Grant, R. F., Z. A. Mekonnen, and W. J. Riley. "Modelling climate change impacts on an Arctic polygonal tundra. Part 1: Rates of permafrost thaw depend on changes in vegetation and drainage." Journal of Geophysical Research-Biogeosciences 124(5), 1308–22 (2019). [DOI:10.1029/2018JG004644]

Topic Areas:

  • Research Area: Earth and Environment Systems Data Management
  • Research Area: Terrestrial Ecosystem Science
  • Research Area: Carbon Cycle, Nutrient Cycling
  • Research Area: Next-Generation Ecosystem Experiments (NGEE)

Division: SC-33.1 Earth and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Jan 11, 2022
No Honor Among Copper Thieves
Findings provide a novel means to manipulate methanotrophs for a variety of environmental and in [more...]

Dec 06, 2021
New Genome Editing Tools Can Edit Within Microbial Communities
Two new technologies allow scientists to edit specific species and genes within complex laborato [more...]

Oct 27, 2021
Fungal Recyclers: Fungi Reuse Fire-Altered Organic Matter
Degrading pyrogenic (fire-affected) organic matter is an important ecosystem function of fungi i [more...]

Oct 19, 2021
Microbes Offer a Glimpse into the Future of Climate Change
Scientists identify key features in microbes that predict how warming affects carbon dioxide emi [more...]

Aug 25, 2021
Assessing the Production Cost and Carbon Footprint of a Promising Aviation Biofuel
Biomass-derived DMCO has the potential to serve as a low-carbon, high-performance jet fuel blend [more...]

List all highlights (possible long download time)