Carbonaceous Aerosol Emissions Research Articles

Carbonaceous Aerosol Emissions from Household Biofuel Combustion in China

Field measurements were conducted in four representative rural areas across China to determine carbonaceous aerosol emissions from combustion of household biofuel. Results showed that the size distribution of both black carbon (BC) and organic carbon (OC) peaked at 0.26-0.38 microm. OC accounted for a significant fraction of fine particles from wheat residue combustion across all size categories, whereas both BC and OC accounted for a significant fraction of fine particles from fuel wood combustion across all size categories. The emission factors for crop wastes are 0.43 +/- 0.32 and 1.93 +/- 1.00 g/kg for BC and OC, respectively. The emission factors for woody fuel were 1.49 +/- 0.69 g/kg and 1.13 +/- 0.40 g/kg for BC and OC, respectively. Woody fuel BC-to-PM2.5 ratios were significantly higher than the ratios from crop waste, ranging from 36.40 to 71.18%, relative to crop waste BC-to-PM2.5 ratios which ranged from 1.70 to 33.52%. Woody fuel also had high BC-to-OC ratios, ranging from 0.95 to 2.51. Woody fuel combustion accounts for approximately two-thirds of China's estimated 430 Gg of BC emissions and crop waste combustion accounts for approximately 80% of China's 922 Gg of OC emissions from household biofuel combustion in 2005.

Projections of SO2, NOx and carbonaceous aerosols emissions in Asia

Estimates of Asian emissions of air pollutants and carbonaceous aerosols and their mid-term projections have been changing significantly in the last years. The remote sensing community has shown that increase in NOx in Central East Asia is much stronger than any of the emission inventories or projections indicated so far. A number of studies reviewing older estimates appeared. Here, we review the key contributions and compare them to the most recent results of the GAINS model application for Asia and to the SRES projections used in the IPPC work. The recent projections indicate that the growth of emissions of SO2 in Asia should slow down significantly towards 2010 or even stabilize at the current level. For NOx, however, further growth is projected although it will be most likely slower that in the last decade, owing to introduction of measures in transport. Emissions of carbonaceous aerosols (black carbon and organic carbon) are expected to decline after 2010, largely due to reduced use of biofuels in residential sector and efficiency improvements. The estimates of these emissions are burdened with significantly larger uncertainties than SO2 and NOx; even for the year 2000 the differences in estimates between studies are up to a factor of 2.

A global emission inventory of carbonaceous aerosol from historic records of fossil fuel and biofuel consumption for the period 1860–1997

Abstract. Country by country emission inventories for carbonaceous aerosol for the period 1860 to 1997 have been constructed on the basis of historic fuel production, use and trade data sets published by the United Nation's Statistical Division UNSTAT (1997), Etemad et al. (1991) and Mitchell (1992, 1993, 1995). The inventories use emission factors variable over time, which have been determined according to changes in technological development. The results indicate that the industrialisation period since 1860 was accompanied by a steady increase in black carbon (BC) and primary organic carbon (POC) emissions up to 1910. The calculations show a moderate decrease of carbonaceous aerosol emissions between 1920 and 1930, followed by an increase up to 1990, the year when emissions began to decrease again. Changes in BC and POC emissions prior to the year 1950 are essentially driven by the USA, Germany and the UK. The USSR, China and India become substantial contributors to carbonaceous aerosol emissions after 1950. Emission maps have been generated with a 1°×1° resolution based on the relative population density in each country. They will provide a helpful tool for assessing the effect of carbonaceous aerosol emissions on observed climate changes of the past.

Linking future aerosol radiative forcing to shifts in source activities

We model future direct radiative forcings of the major anthropogenic aerosol species, sulfate, black and organic carbon, within industrial, power, transport, and residential sectors and biomass burning. A sectoral perspective helps to inform mitigation directions. More accurate projections are facilitated by recent carbonaceous aerosol emission estimates that incorporate projected technology changes, now available for the Intergovernmental Panel on Climate Change scenarios A1B and B1, for 2030 and 2050. Net present‐day model anthropogenic forcing is −0.11 W m−2. By 2050 this doubles (A1B) or drops by 30% (B1), depending mostly on sulfate changes in the industry and power sectors. Present‐day (non‐biomass burning) BC forcing comes mostly from residential sources (+0.09 W m−2), however this is projected to decrease by more than a factor of 10 by 2050. Future BC forcing is projected to come mostly from transport, changing from +0.06 W m−2 in 2000 to +0.04 (B1) or +0.07 W m−2 (A1B) by 2050.

Inventory of black carbon and organic carbon emissions from China

We present detailed high-resolution emission inventories of black carbon (BC) and organic carbon (OC) from China in the year 2000. The latest fuel consumption data, including fossil and biomass fuels and socio-economic statistics were obtained from government agencies, mostly at the county level. Some new emission factors (EFs) from local measurements also were used. National and regional summaries of emissions are presented, and gridded emissions at 0.2°×0.2° resolution are shown. Our calculated emissions were 1500 Gg for BC and 4100 Gg for OC, mainly due to the burning of coal and biofuels. The carbonaceous aerosol emissions estimated here are higher than those in previous studies, mainly because coal burning by rural industries and residences were previously underestimated. More carbonaceous aerosols are emitted from eastern China than western China. A strong seasonal dependence is observed for emissions, with peaks in May and October and low emissions in April and July; this seasonality is mainly due to patterns in residential heating and agriculture waste open burning.

Impact of carbonaceous aerosol emissions on regional climate change

The past and future evolution of atmospheric composition and climate has been simulated with a version of the Max Planck Institute Earth System Model (MPI-ESM). The system consists of the atmosphere, including a detailed representation of tropospheric aerosols, the land surface, and the ocean, including a model of the marine biogeochemistry which interacts with the atmosphere via the dust and sulfur cycles. In addition to the prescribed concentrations of carbon dioxide, ozone and other greenhouse gases, the model is driven by natural forcings (solar irradiance and volcanic aerosol), and by emissions of mineral dust, sea salt, sulfur, black carbon (BC) and particulate organic matter (POM). Transient climate simulations were performed for the twentieth century and extended into the twenty-first century, according to SRES scenario A1B, with two different assumptions on future emissions of carbonaceous aerosols (BC, POM). In the first experiment, BC and POM emissions decrease over Europe and China but increase at lower latitudes (central and South America, Africa, Middle East, India, Southeast Asia). In the second experiment, the BC and POM emissions are frozen at their levels of year 2000. According to these experiments the impact of projected changes in carbonaceaous aerosols on the global mean temperature is negligible, but significant changes are found at low latitudes. This includes a cooling of the surface, enhanced precipitation and runoff, and a wetter surface. These regional changes in surface climate are caused primarily by the atmospheric absorption of sunlight by increasing BC levels and, subsequently, by thermally driven circulations which favour the transport of moisture from the adjacent oceans. The vertical redistribution of solar energy is particularly large during the dry season in central Africa when the anomalous atmospheric heating of up to 60 W m−2 and a corresponding decrease in surface solar radiation leads to a marked surface cooling, reduced evaporation and a higher level of soil moisture, which persists throughout the year and contributes to the enhancement of precipitation during the wet season.

Effect of carbonaceous aerosols on surface temperature in the mid twentieth century

Simulations using a climate model are used to investigate the possible impact of increasing emissions of carbonaceous aerosols on near‐surface temperature in the mid‐20th century. The annual global mean near‐surface temperature change from the mid‐20th century onward is reasonably described by a model that is forced by changes in most of the known climate forcing agents including an increase in carbonaceous aerosols, though it can also be well reproduced without increases in carbonaceous aerosols. However, if we consider spatio‐temporal structure of the changes in the near‐surface temperature, an increase in carbonaceous aerosols is definitely required for the model to represent changes in the near‐surface temperature in the mid‐century, in particular, cooling trends in the tropical and subtropical continents. The significance of an increase in carbonaceous aerosols as an indispensable contributor to mid‐20th century temperature changes is confirmed with the use of an optimal fingerprinting methodology.

Carbonaceous aerosol emissions from India

Budget estimate for carbonaceous aerosols including black carbon (BC) and organic carbon, emitted from the combustion of various fuels, is very important for regional climate studies. Emission factors for carbonaceous aerosols from bio-fuels and soft coke were determined in a controlled combustion study. The emission factors thus obtained along with those available for other fossil fuels consumed in different sectors have been applied to assess the budget for carbonaceous aerosols from India. Preliminary calculations give a range of 1.6–1.8 Tg of carbonaceous aerosols that include 0.4–1.4 Tg of BC. A major (∼80%) portion of carbonaceous aerosols emitted from India is found to originate from the use of biomass for energy as 70–80% of energy requirement in rural India is met by combustion of traditional bio-fuels.

Historical emissions of carbonaceous aerosols from biomass and fossil fuel burning for the period 1870–2000

Historical changes of black carbon (BC) and particulate organic matter (POM) emissions from biomass burning (BB) and fossil fuel (FF) burning are estimated from 1870 to 2000. A bottom‐up inventory for open vegetation (OV) burning is scaled by a top‐down estimate for the year 2000. Monthly and interannual variations are derived over the time period from 1979 to 2000 based on the TOMS satellite aerosol index (AI) and this global map. Prior to 1979, emissions are scaled to a CH4 emissions inventory based on land‐use change. Biofuel (BF) emissions from a recent inventory for developing countries are scaled forward and backward in time using population statistics and crop production statistics. In developed countries, wood consumption data together with emission factors for cooking and heating practices are used for biofuel estimates. For fossil fuel use, we use fuel consumption data and specific emission factors for different fuel use categories to develop an inventory over 1950–2000, and emissions are scaled to a CO2 inventory prior to that time. Technology changes for emissions from the diesel transport sector are included. During the last decade of this time period, the BC and POM emissions from biomass burning (i.e., OV + BF) contribute a significant amount to the primary sources of BC and POM and are larger than those from FF. Thus 59% of the NH BC emissions and 90% of the NH POM emissions are from BB in 2000. Fossil fuel consumption technologies are needed prior to 1990 in order to improve estimates of fossil fuel emissions during the twentieth century. These results suggest that the aerosol emissions from biomass burning need to be represented realistically in climate change assessments. The estimated emissions are available on a 1° × 1° grid for global climate modeling studies of climate changes.

Residential Biofuels in South Asia: Carbonaceous Aerosol Emissions and Climate Impacts

High concentrations of pollution particles, including "soot" or black carbon, exist over the Indian Ocean, but their sources and geographical origins are not well understood. We measured emissions from the combustion of biofuels, used widely in south Asia for cooking, and found that large amounts of carbonaceous aerosols are emitted per kilogram of fuel burnt. We calculate that biofuel combustion is the largest source of black carbon emissions in India, and we suggest that its control is central to climate change mitigation in the south Asian region.

On the future of carbonaceous aerosol emissions

This paper presents the first model‐based forecasts of future emissions of the primary carbonaceous aerosols, black carbon (BC) and organic carbon (OC). The forecasts build on a recent 1996 inventory of emissions that contains detailed fuel, technology, sector, and world‐region specifications. The forecasts are driven by four IPCC scenarios, A1B, A2, B1, and B2, out to 2030 and 2050, incorporating not only changing patterns of fuel use but also technology development. Emissions from both energy generation and open biomass burning are included. We project that global BC emissions will decline from 8.0 Tg in 1996 to 5.3–7.3 Tg by 2030 and to 4.3–6.1 Tg by 2050, across the range of scenarios. We project that OC emissions will decline from 34 Tg in 1996 to 24–30 Tg by 2030 and to 21–28 Tg by 2050. The introduction of advanced technology with lower emission rates, as well as a shift away from the use of traditional solid fuels in the residential sector, more than offsets the increased combustion of fossil fuels worldwide. Environmental pressures and a diminishing demand for new agricultural land lead to a slow decline in the amount of open biomass burning. Although emissions of BC and OC are generally expected to decline around the world, some regions, particularly South America, northern Africa, the Middle East, South Asia, Southeast Asia, and Oceania, show increasing emissions in several scenarios. Particularly difficult to control are BC emissions from the transport sector, which increase under most scenarios. We expect that the BC/OC emission ratio for energy sources will rise from 0.5 to as much as 0.8, signifying a shift toward net warming of the climate system due to carbonaceous aerosols. When biomass burning is included, however, the BC/OC emission ratios are for the most part invariant across scenarios at about 0.2.

Global modelling of secondary organic aerosol in the troposphere: a sensitivity analysis

Abstract. A global 3-dimensional chemistry/transport model able to describe O3, NOx, Volatile Organic Compounds (VOC), sulphur and NH3 chemistry has been extended to simulate the temporal and spatial distribution of primary and secondary carbonaceous aerosols in the troposphere focusing on Secondary Organic Aerosol (SOA) formation. A number of global simulations have been performed to determine a possible range of annual global SOA production and investigate uncertainties associated with the model results. The studied uncertainties in the SOA budget have been evaluated to be in decreasing importance: the potentially irreversible sticking of the semi-volatile compounds on aerosols, the enthalpy of vaporization of these compounds, the partitioning of SOA on non-carbonaceous aerosols, the conversion of aerosols from hydrophobic to hydrophilic, the emissions of primary carbonaceous aerosols, the chemical fate of the first generation products and finally the activity coefficient of the condensable species. The large uncertainties associated with the emissions of VOC and the adopted simplification of chemistry have not been investigated in this study. Although not all sources of uncertainties have been investigated, according to our calculations, the above factors within the experimental range of variations could result to an overall uncertainty of about a factor of 20 in the global SOA budget. The global annual SOA production from biogenic VOC might range from 2.5 to 44.5 Tg of organic matter per year, whereas that from anthropogenic VOC ranges from 0.05 to 2.62 Tg of organic matter per year. These estimates can be considered as a lower limit, since partitioning on coarse particles like nitrate, dust or sea-salt, together with the partitioning and the dissociation of the semi-volatile products in aerosol water has been neglected. Comparison of model results to observations, where available, shows a better agreement for the upper budget estimates than for the lower ones.

Climate forcing by carbonaceous and sulfate aerosols

An atmospheric general circulation model is coupled to an atmospheric chemistry model to calculate the radiative forcing by anthropogenic sulfate and carbonaceous aerosols. The latter aerosols result from biomass burning as well as fossil fuel burning. The black carbon associated with carbonaceous aerosols is absorbant and can decrease the amount of reflected radiation at the top-of-the-atmosphere. In contrast, sulfate aerosols are reflectant and the amount of reflected radiation depends nonlinearly on the relative humidity. We examine the importance of treating the range of optical properties associated with sulfate aerosol at high relative humidities and find that the direct forcing by anthropogenic sulfate aerosols can decrease from −0.81 W m-2 to −0.55 Wm-2 if grid box average relative humidity is not allowed to increase above 90%. The climate forcing associated with fossil fuel emissions of carbonaceous aerosols is calculated to range from +0.16 to +0.20 Wm-2, depending on how much organic carbon is associated with the black carbon from fossil fuel burning. The direct forcing of carbonaceous aerosols associated with biomass burning is calculated to range from −0.23 to −0.16 Wm-2. The pattern of forcing by carbonaceous aerosols depends on both the surface albedo and the presence of clouds. Multiple scattering associated with clouds and high surface albedos can change the forcing from negative to positive.