Effects of Tropical Deforestation on Tropospheric Chemistry: A 10-year Study using GEOS-Chem Prasad Kasibhatla, Duke University James Randerson and Yang Chen, University of California Irvine Guido van der Werf, Vrije University Louis Giglio, Science Systems and Applications, Inc. Jim Collatz, NASA Goddard Space Flight Center Ruth DeFries, Columbia University Doug Morton, University of Maryland 4 th GEOS-Chem Users’ Meeting April 9, 2009

Global C Budget for 1990s Source: IPCC AR4 WG1 Report black – steady-state preindustrial red – anthropogenic perturbation +3.2 Gt C/yr LUC Gt C/yr (large uncertainty) - primarily tropical deforestation  model vs satellite measurements of CO in regions of intense deforestation  model simulations with and without fire emissions in deforestation regions

Model Simulations Model  GEOS-CHEM v driven by GEOS-4 4x5 met fields Emissions Fossil fuel combustion: EDGAR with regional inventories for North America (NEI), Europe (EMEP), Asia (Streets), and Mexico(BRAVO) - representative of year ~2000 Biofuel combustion: Yevich and Logan Biogenic VOCs: MEGAN Biomass burning: Annually-varying, monthly GFED2 emissions Runs Run 1: full chemistry simulation (2005 met fields for 2007) Run 2: tagged CO simulation using monthly-mean OH fields from Run 1 Run 3: full chemistry simulation without biomass burning emissions in grid cells with detected humid tropical forest deforestation between (Hansen et al., PNAS, 2008)

BONA TENA EQAS BOAS-east EURO SHSA NHSA CEAM MIDE NHAF SHAF SEAS CEAS AUST Tagged CO Biomass Burning Regions BOAS-west For this talk, focus on  SHSA Total fire emissions = 314 Tg C/yr; deforest. fire emissions = 209 Tg C/yr  EQAS Total fire emissions = 255 Tg C/yr; deforest. fire emissions = 255 Tg C/yr (Global fire emissions = 2415 Tg C/yr; deforest. fire emissions = 813 Tg C/yr)

MOPITT Model Total In-region fires Out-of-region fires Fossil fuel/biofuel Methane oxidation Biogenic HC oxidation 700 mb CO CO (ppb) year Model vs MOPITT Regional Average CO over EQAS Large interannual variability – generally well simulated by model

Model vs MOPITT Regional Average CO over SHSA MOPITT Model Total In-region fires Out-of-region fires Fossil fuel/biofuel Methane oxidation Biogenic HC oxidation CO (ppb) 700 mb CO year Seasonal fire season peak reasonably well simulated, but but modeled interannual variability is higher than observed Significant overestimate in non-fire season suggesting biogenic hydrocarbon oxidation source of CO is too high

700 mb CO (ppb): Model vs MOPITT JUL AUG SEP OCT MOPITT Model Model - MOPITT 2005

September Surface O3 (ppb): With – Without Deforestation SEP 1997 SEP 2000 SEP 2005 SEP 2006

September Surface PM2.5 (µg m -3 ): With – Without Deforestation SEP 1997 SEP 2000 SEP 2005 SEP 2006

Annual N Deposition: With/Without Deforestation

October 1997 OH % Change: 100*(With – Without Def.)/(With Def) Surface 500 mb 300 mb 700 mb

Variability of regional average modeled CO in general agreement with MOPITT CO over EQAS and SHSA  lends confidence to GFED2 C emissions from tropical deforestation since these are major deforestation regions, BUT interannual variations over SHSA seems to be overestimated. and MORE IMPORTANTLY, poor simulations of spatial patterns over SHSA. GFED pan-tropical deforestation fire C emissions ~0.8 P C yr -1  best estimate of committed C flux ~ Pg C yr -1 Significant effect of tropical deforestation on local/regional air quality parameters  next steps will involve analysis of human health/ecological effects (Miriam Marlier), in concert with next generation of GFED product and regional atmospheric chemistry modeling over SHSA and EQAS. Summary

 NASA (funding)  Bob Yantosca, Philippe Le Sager, Claire Carouge (model)  Louisa Emmons, Merritt Deeter, and MOPITT team (MOPITT data)  Jennifer Logan (discussions)  Jesse Kenyon (programmer) Acknowledgements