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Title: Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories

Abstract

Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through changing terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignitions and suppression (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to quantify the impacts of changes in human ignition and suppression on fire dynamics and associated carbon and water cycles. We find that the impact is to significantly reduce the 20th century global burned area by a century average of 38 Mha/yr and by 103 Mha/yr at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire weakens the upward trend in global runoff throughout the century by 6% and enhances the upward trend in global evapotranspiration since ~ 1945 by 7%. In addition, themore » above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.« less

Authors:
; ; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1421333
Report Number(s):
PNNL-SA-128110
Journal ID: ISSN 0921-8181; KP1703020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Global and Planetary Change
Additional Journal Information:
Journal Volume: 162; Journal Issue: C; Journal ID: ISSN 0921-8181
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
CESM; fire modeling; Earth System Model

Citation Formats

Li, Fang, Lawrence, David M., and Bond-Lamberty, Ben. Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories. United States: N. p., 2018. Web. doi:10.1016/j.gloplacha.2018.01.002.
Li, Fang, Lawrence, David M., & Bond-Lamberty, Ben. Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories. United States. doi:10.1016/j.gloplacha.2018.01.002.
Li, Fang, Lawrence, David M., and Bond-Lamberty, Ben. Thu . "Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories". United States. doi:10.1016/j.gloplacha.2018.01.002.
@article{osti_1421333,
title = {Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories},
author = {Li, Fang and Lawrence, David M. and Bond-Lamberty, Ben},
abstractNote = {Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through changing terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignitions and suppression (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to quantify the impacts of changes in human ignition and suppression on fire dynamics and associated carbon and water cycles. We find that the impact is to significantly reduce the 20th century global burned area by a century average of 38 Mha/yr and by 103 Mha/yr at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire weakens the upward trend in global runoff throughout the century by 6% and enhances the upward trend in global evapotranspiration since ~ 1945 by 7%. In addition, the above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.},
doi = {10.1016/j.gloplacha.2018.01.002},
journal = {Global and Planetary Change},
issn = {0921-8181},
number = C,
volume = 162,
place = {United States},
year = {2018},
month = {3}
}