Energy is vital to human society but significantly contributes to the deterioration of environmental quality and the global issue of climate change. Biomass and fossil fuels are important energy sources but have distinct pollutant emission characteristics during the burning process. This study aimed at attributing radiative forcing of climate forcers, including greenhouse gases but also short-lived climate pollutants, from the burning of fossil and biomass fuels, and the spatiotemporal characteristics. We found that air pollutant emissions from the burning process of biofuel and fossil fuels induced RFs of 68.2 +/- 36.8 mW m(-2) and 840 +/- 225 mW m(-2), respectively. The relatively contribution of biomass burning emissions was 7.6% of that from both fossil and biofuel combustion processes, while its contribution in energy supply was 11%. These relative contributions varied obviously across different regions. The per unit energy consumption of biomass fuel in the developed regions, such as North America (0.57 +/- 0.33 mW m(-2)/10(7)TJ) and Western Europe (0.98 +/- 0.79 mW m(-2)/10(7)TJ), had higher impacts of combustion emission related RFs compared to that of developing regions, like China (0.40 & PLUSMN; 0.26 mW m(-2)/10(7)TJ), and South and South-East Asia (0.31 +/- 0.71 mW m(-2)/10(7)TJ) where low efficiency biomass burning in residential sector produced significant amounts of organic matter that had a cooling effect. Note that the study only evaluated fuel combustion emission related RFs, and those associated with the production of fuels and land use change should be studied later in promoting a comprehensive understanding on the climate impacts of biomass utilization.

Given abundant energy and mineral resources in northwestern China, the west-east energy and mineral product transmission program play an increasingly important role in China's energy supply and consumption since the 2000s. Rapid growing energy and mineral products under this program might release increasing carbon emissions, causing climate and environmental consequences in northwestern China, which seems to be overlooked before. Here, a multiregional input-output analysis (MRIO) was conducted to investigate the temporal and spatial changes in black carbon (BC) emissions embodied in west-east energy and mineral product transmission from 2007 to 2012. Results were used to estimate BC's climate and environmental impact on China, focusing on northwestern China. The results show that BC emission flow patterns have been altered dramatically in China's domestic trade from 2007 through 2012. By 2012, 48%-77% of the consumption-based BC emissions from welldeveloped Beijing-Tianjin metropolises, East Coast, and South Coast regions were outsourced to other, primarily less-developed regions, of which northwestern China was the largest net BC emission outflow region at 48.8 Gg. The BC radiative forcing over China embodied in the west-east energy transmission was quantified using a compact Earth system model OSCAR. Model estimation shows that more than 30% of BC radiative forcing in northwestern China was related to the consumption from other regions across China. Central and eastern China were two significant contributors to the BC radiative forcing in northwestern China. Severe BC environmental inequality embodied in interprovincial trade was also identified in northwestern and central China provinces among 30 Chinese provinces. Inner Mongolia, Shaanxi, Ningxia, and Xinjiang in northwestern China experienced the most prominent climate and environmental losses via trade with well-developed provinces. These results provide references to alleviate trade-related pollution and climate impacts and to promote BC environmental equality in China.

In this study, we categorized detailed mass-based emission factors (EFs) by age, calculated new estimates of fuel use, and developed spatially resolved emission inventories of constituents (PM2.5, black carbon [BC], and organic carbon [OC]) in the fine aerosol generated by the on-road transport sector in India. On a national level, this sector released an estimated 355 (104-607) Gg y(-1), 137 (47-227) Gg y(-1), and 106 (34-178) Gg y(-1) of PM2.5, BC, and OC, respectively, for the base year 2013, contributing nearly 7%, 17%, and 6% of the total emissions for each constituent. Although super-emitter vehicles comprised only 24% of the total traffic volume, they were responsible for 67% and 47% of the national PM2.5 and BC emissions, respectively, which indicates that eliminating these vehicles may rapidly reduce emissions from the on-road transport sector in India. To predict the direct radiative forcing (DRF) from BC emissions in this sector, we then input emission estimates for the carbonaceous aerosols into the Community Atmosphere Model (CAM5) global climate model and found a positive DRF of up to 6 W m(-2) at the top of the atmosphere (TOA) and a negative DRF of up to 10 W m(-2) at the surface, suggesting that as much as 16 W m(-2) of energy remains trapped within the atmosphere. With the rapid economic growth and continued urbanization, the transport sector in India is likely to further expand in the future and hence requires immediate attention in order to reduce the BC burden and improve air quality in the nation.

The Himalayan cryosphere borders global hotspots for emissions of black carbon (BC), a carbonaceous aerosol with a short atmospheric lifespan and potentially significant impacts on glaciers and snow cover. BC in the atmosphere absorbs radiation efficiently, leading to localized positive climate forcing. BC may also be deposited onto snow and ice surfaces, thereby changing their albedo. This review presents up-to-date observational data of BC in the atmosphere and in snow and ice, as well as its effects on the cryosphere in the Hindu-Kush-Himalayan (HKH) region along the northern edge of South Asia. Significant spatial variation exists in the measured concentrations of BC in the atmosphere and cryosphere. A strong seasonal pattern exists, with highest concentrations in the pre-monsoon and lowest during the monsoon. Existing observations show bias towards certain areas, with a noticeable lack of measurements on the south side of the Himalaya. Significant uncertainty persists in the emissions estimates of BC in the HKH region, with a standard deviation of regional emissions from various emission inventories of 0.5150 x 10(-9) kg m(-2) S-1, or 47.1% of the mean (1.0931 x 10(-9) kg m(-2) S-1). This and other uncertainties, including poor model resolution, imprecision in deposition modeling, and incongruities among measurement types, propagate through simulations of BC concentration in atmosphere and cryosphere. Modeled atmospheric concentrations can differ from observations by as much as a factor of three with no systematic bias, and modeled concentrations in snow and ice can differ from observations by a factor of 60 in certain regions. In the Himalaya, estimates of albedo change due to BC range from about 2 to 10%, estimates of direct radiative forcing due to BC in the atmosphere from (-2)-7 W m(-2), and surface forcing estimates from 0 to 28 W m(-2), though every forcing estimate uses its own definition, with varying degrees of complexity and numbers of feedbacks. We find the most important course of further study to be model verification, enabled by increasing observational data and in this region and consistent measurement protocol. (C) 2015 Published by Elsevier Ltd.

Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr(-1) in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m(-2) with 90% uncertainty bounds of (+0.08, +1.27) W m(-2). Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m(-2). Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m(-2) with 90% uncertainty bounds of +0.17 to +2.1 W m(-2). Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m(-2), is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (-0.50 to +1.08) W m(-2) during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (-0.06 W m(-2) with 90% uncertainty bounds of -1.45 to +1.29 W m(-2)). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

, Accurate modelling of the radiative forcing due to Arctic aerosols requires an adequate knowledge about the spectral, spatial and temporal variability of the aerosol. This needs contrasts with the limited measurements of Arctic aerosol characteristics. This paper presents two different approaches to incorporate Arctic aerosols in the regional climate model HIRHAM to overcome this problem. In the first method, Arctic aerosol properties are described via a mixture of different components from the global aerosol data set (GADS). The second method derives the aerosol model input parameter from an Arctic airborne measurement campaign (ASTAR) via a data transformation. Results from a one-dimensional radiative transfer model for a case study are presented for two selected days of March 2000, one with a high and another with a lower aerosol loading, which were considered to be representative for the Arctic spring aerosol loading. The calculated heating rate anomalies are sensitive to the assumed aerosol characteristics (absorption characteristics, particle radius, chemical composition, mass-mixing ratio). The performed study showed the importance of both methods for modelling solar radiative forcing due to Arctic aerosols. For the 2 days selected, calculated local solar heating rate anomalies between 0.05 and 0.3 K day(-1) were achieved. An application of a high-resolution regional climate model is presented to determine the regional climatic impact of Arctic aerosols during March 2000. The aerosol effect induced a substantial spatial variability at the regional scale and varies between a cooling of 2 K in the Baffin Bay and Laptev Sea and a warming of 3 K in the Beaufort Sea. Arctic aerosol loading changed the sea level pressure patterns over the Arctic Ocean with implications for additional feedbacks on a coupled atmosphere-ocean-sea ice model of the Arctic. (C) 2004 Elsevier Ltd. All rights reserved.

The effect of black carbon (BC) on climate forcing is potentially important, but its estimates have large uncertainties due to a lack of sufficient observational data. The BC mass concentration in the southeastern US was measured at a regionally representative site, Mount Gibbes (35.78 degreesN, 82.29 degreesW, 2006 m MSL). The air mass origin was determined using 48-h back trajectories obtained from the hybrid single-particle Lagrangian integrated trajectory model. The highest average concentration is seen in polluted continental air masses and the lowest in marine air masses. During the winter, the overall average BC value was 74.1 ng m(-3), whereas the overall summer mean BC value is higher by a factor of 3. The main reason for the seasonal difference may be enhanced thermal convection during summer, which increases transport of air pollutants From the planetary boundary layer of the surrounding urban area to this rural site. In the spring of 1998. abnormally high BC concentrations from the continental sector were measured. These concentrations were originating from a biomass burning plume in Mexico. This was confirmed by the observations of the Earth probe total ozone mapping spectrometer. The BC average concentrations of air masses transported from the polluted continental sector during summer are low on Sunday to Tuesday with a minimum value of 256 ng m(-3) occurring on Monday, and high on Wednesday to Friday with a maximum value of 379 ng m(-3) occurring on Friday. The net aerosol radiative forcing (scattering effects plus absorption effects) per unit vertical depth at 2006 m MSL is calculated to be - 1.38 x 10(-3) W m(-3) for the southeastern US. The magnitude of direct radiative forcing by aerosol scattering is reduced by 15 +/- 7% due to the BC absorption. (C) 2001 Elsevier Science Ltd. All rights reserved.

Human activity has perturbed the Earth's energy balance by altering the properties of the atmosphere and the surface. This perturbation is of a size that would be expected to lead to significant changes in climate. in recent years, an increasing number of possible human-related climate change mechanisms have begun to be quantified. This paper reviews developments in radiative forcing that have occurred since the second assessment report of the Intergovernmental Panel on Climate Change (IPCC), and proposes modifications to the values of global-mean radiative forcings since pre-industrial times given by IPCC. The forcing mechanisms which are considered here include those due to changes in concentrations of well-mixed greenhouse gases, tropospheric and stratospheric ozone, aerosols composed of sulphate, soot, organics and mineral dust (including their direct and indirect effects), and surface albedo. For many of these mechanisms, the size, spatial pattern and, for some, even the sign of their effect remain uncertain. Studies which have attributed observed climate change to human activity have considered only a subset of these mechanisms; their conclusions may not prove to be robust when a broader set is included. (C) 1999 Elsevier Science B.V. All rights reserved.