Browsing by Author "Kasibhatla, Prasad S"

This study examines the seasonal and interannual variabilities of carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), over the years of 2005-2016 by using outputs from the NASA GISS ModelE simulations and observations from the OMI instrument aboard Aura, AERONET stations in Amazon region, and the GoAmazon aircraft campaigns.

Simulated seasonal variations and spatial distributions of surface concentrations of BC and OC in Amazon agree well with those of biomass burning emissions. The concentrations are the highest in the dry season (July-September) and lowest in the wet season (February-May), and the locations of high concentrations follow those of high emissions. ModelE is found to underestimate concentrations of OC and BC. Comparisons of the vertical profiles of OC from ModelE with GoAmazon observations in 2014 show that ModelE underestimates OC at all altitudes. In the dry season, when biomass burning dominates, ModelE captures 42%-86% of OMI AAOD in Amazon over 2005-2016, suggesting a low bias in simulated BC concentrations. Simulated seasonal variations in AOD and AAOD in ModelE differ from OMI observations; simulated AOD (AAOD) values are the highest in the dry season, while OMI observed AOD (AAOD) values are the highest in October-January.

Interannual variations in BC and OC are quantified by relative deviation from the mean (RDEVM). Interannual variations of BC and OC in dry season are much higher than those in wet season. RDEVM values are in the range of -63.2% to 127.2% (-70.8% to 143.8%) for BC (OC) in dry season and in the range of -17.8% to 32.7% (-26.3% to 53.4%) for BC (OC) in wet season. Simulated OC concentrations have larger interannual variability than simulated BC for both the dry and wet seasons. We also found that, compared with OMI observations, ModelE overestimates the interannual variability of AOD and AAOD in the Amazon region for both the dry and wet seasons.

Results from this study contribute to the understanding of aerosol distributions in the Amazon and have implications for the impact of carbonaceous aerosols on climate on an interannual timescale.

This research evaluates the potential for regulatory measures governing oil palm plantation expansion, and corporate voluntary sustainability commitments in the oil palm industry, to contribute to forest protection and greenhouse gas emissions reduction goals at regional and national scales, using case studies from Indonesia and Gabon. Globally, agricultural production will need to increase by 60–110% by 2050, to meet anticipated demand for food, fiber and biofuels (Alexandratos and Bruinsma, 2012; Tilman et al., 2011). Achieving this increase without negative consequences for forests, biodiversity, and climate will require innovative solutions including increasing productivity, minimizing waste and inefficiencies, improving food distribution and access, shifting diet preferences, and optimizing land use (Foley et al., 2011; Godfray et al., 2010; Newton et al., 2013). Palm oil, which comprises 35% of global vegetable oil consumption, is emblematic of this challenge (Sayer et al., 2012). The production of palm oil is increasing more rapidly than any other oil crop, and an increasingly urban and wealthy global population is anticipated to drive further demand (Hertel, 2011). In Southeast Asia, where 87% of global palm oil production is currently concentrated, industrial-scale plantations nearly quadrupled in extent from 1990–2010 (Gunarso et al., 2013), and drove the conversion of millions of hectares of forest and peat lands (Carlson et al., 2013; Koh et al., 2011). There is therefore growing concern among environmental advocates that, if appropriate safeguards are not put in place, future expansion of oil palm cultivation will reflect historical patterns, leading to the continued destruction of biodiversity- and carbon-rich forest landscapes (Linder, 2013; Wich et al., 2014). In response to these concerns, government and private sector stakeholders have proposed or established policies aimed at minimizing the negative environmental consequences of oil palm production. Here, I investigate the potential impacts of these programs and policies by examining historical trends in industrial-scale oil palm plantation expansion patterns, predicting business-as-usual trajectories of future plantation expansion, and estimating the potential impacts of alternative policy scenarios on future plantation development, and on forests, peatlands, and carbon stocks. In Chapter 1, I provide background information on palm oil and its uses, cultivation requirements, production patterns, and documented environmental impacts. I additionally discuss actual or proposed government regulations and private sector sustainability initiatives that are relevant in the contexts of Indonesia and/or Gabon. In Chapter 2, I present an analysis of patterns of oil palm expansion, and impacts on forest and peat lands, in Indonesia from 1995–2015. In Chapter 3, I develop predictions of future Indonesian oil palm expansion under a range of policy scenarios, and provide estimates of the extent to which these scenarios will contribute to forest protection and concomitant CO2 emissions reductions. In Chapter 4, I evaluate the extent to which greenhouse gas emissions reductions in the oil palm sector will contribute to Indonesia’s national mitigation goals, given uncertainties in the current national greenhouse gas inventory system. In Chapter 5, I develop national suitability maps for oil palm cultivation in Gabon, a new frontier of oil palm expansion, and identify priority areas which have the potential to support production goals while protecting forest landscapes. Finally, I summarize findings across these studies, present next steps, and provide concluding remarks in Chapter 6.