Quantifying the role of fire in the Earth system – Part 1: Improved global fire modeling in the Community Earth System Model (CESM1)

[摘要] Modeling fire as an integral part of an Earth system model (ESM) is vitalfor quantifying and understanding fire–climate–vegetation interactions on aglobal scale and from an Earth system perspective. In this study, weintroduce to the Community Earth System Model (CESM) the new global fireparameterization proposed by Li et al. (2012a, b), now with a more realisticrepresentation of the anthropogenic impacts on fires, with aparameterization of peat fires, and with other minor modifications. Theimproved representation of the anthropogenic dimension includes the firstattempt to parameterize agricultural fires, the economic influence on fireoccurrence, and the socioeconomic influence on fire spread in a global firemodel – also an alternative scheme for deforestation fires.

The global fire parameterization has been tested in CESM1's land componentmodel CLM4 in a 1850–2004 transient simulation, and evaluated against thesatellite-based Global Fire Emission Database version 3 (GFED3) for1997–2004. The simulated 1997–2004 average global totals for the burned areaand fire carbon emissions in the new fire scheme are 338 Mha yr⁻¹ and2.1 Pg C yr⁻¹. Its simulations on multi-year average burned area, fireseasonality, fire interannual variability, and fire carbon emissions arereasonable, and show better agreement with GFED3 than the current firescheme in CESM1 and modified CTEM-FIRE. Moreover, the new fire scheme alsoestimates the contributions of global fire carbon emissions from differentsources. During 1997–2004, the contributions are 8% from agriculturalbiomass burning, 24% from tropical deforestation and degradation fires,6% from global peat fires (3.8% from tropical peat fires), and 62%from other fires, which are close to previous assessments based on satellitedata, government statistics, or other information sources. In addition, weinvestigate the importance of direct anthropogenic influence (anthropogenicignitions and fire suppression) on global fire regimes during 1850–2004,using CESM1 with the new fire scheme. Results show that the directanthropogenic impact is the main driver for the long-term trend of globalburned area, but hardly contributes to the long-term trend of the globaltotal of fire carbon emissions.

[学科分类] 地球化学与岩石