Wildfire as a Driver of Permafrost Degradation in Boreal and Tundra Ecosystems of Alaska, Siberia and Northeast China: Implications for Environmental and Socio-Economic Impacts.
Abstract
The overall goal of this study is to evaluate the vulnerability of permafrost under climate warming and wildfire disturbances in respect of ecosystems stability, socioeconomic impact, and to provide stakeholders with information for better understanding possible future changes.
In the discontinuous permafrost zone, the presence of vegetation and organic soil layers strongly affect ground thermal regimes due to thermal insulation and offset. Shur and Jorgenson (2007) classified permafrost into five types according to patterns of formation and degradation of permafrost in relation to climate and ecosystems. For each type, permafrost reacts differently to external disturbances. A major threshold is crossed when permafrost thaws after damage or removal of vegetation and upper soil organic layers, e.g., by wildfires. Measurements of ground temperatures indicate a relatively continual warming in most permafrost regions of northern Hemisphere over the last 3 decades and increasing the vulnerability of permafrost to surface disturbances. We applied the process-based permafrost dynamics model GIPL2 developed in the Geophysical Institute Permafrost Lab, University of Alaska Fairbanks, using a historical climate forcing CRU TS 4.0 data-set for retrospective (1901-2015) and five top-ranked global circulation models from the CMIP5/AR5 models and RCPs (2016-2100), as well as various fire severity scenarios for analysis of permafrost dynamics in the future. For model validation, we have acquired a number of long-term records of permafrost temperature from undisturbed and fire-disturbed field sites. The boreal forest and tundra ecosystems with various surface and sub-surface conditions, across selected permafrost domains were examined with respect to fire severity. In some cases, the modeling result shows the dramatic post-fire permafrost changes, such as rapidly rising ground temperatures and enlarging active layer thickness, which leads to talik formation due to the detachment of the permafrost table from seasonally frozen layer and even termination the permafrost because once disturbed, some permafrost types cannot recover. Since the fires are frequent in arctic and boreal areas, and under a warming climate, impact of wildfires can reshape the zonation of northern permafrost.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC24C..08M
- Keywords:
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- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 0702 Permafrost;
- CRYOSPHERE;
- 1637 Regional climate change;
- GLOBAL CHANGE;
- 1817 Extreme events;
- HYDROLOGY