Johann G. Goldammer

Global wildland fire emissions from 1960 to 2000

In many regions of the world, fires are an important and highly variable source of air pollutant emissions, and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric composition. This paper describes the 41-year inventory of vegetation fire emissions constructed for the Reanalysis of the Tropospheric chemical composition over the past 40 years project (RETRO), a global modeling study to investigate the trends and variability of tropospheric ozone and other air pollutants over the past decades. It is the first attempt to construct a global emissions data set with monthly time resolution over such a long period. The inventory is based on a literature review, on estimates from different satellite products, and on a numerical model with a semiphysical approach to simulate fire occurrence and fire spread. Burned areas, carbon consumption, and total carbon release are estimated for 13 continental-scale regions, including explicit treatment of some major burning events such as Indonesia in 1997 and 1998. Global carbon emissions from this inventory range from 1410 to 3140 Tg C/a with the minimum and maximum occurring in 1974 and 1992, respectively (mean of 2078 Tg C/a). Emissions of other species are also reported (mean CO of 330 Tg/a, NO x of 4.6 Tg N/a, CH 2 O of 3.9 Tg/a, CH 4 of 15.4 Tg/a, BC of 2.2 Tg/a, OC of 17.6 Tg/a, SO 2 of 2.2 Tg/a). The uncertainties of these estimates remain high even for later years where satellite data products are available. Future versions of this inventory may benefit from ongoing analysis of burned areas from satellite data going back to 1982.

Fire in ecosystems of boreal Eurasia

Preface. I: Introduction. II: Fire in Boreal Ecosystems: History and Patterns. III: Statistics and Dynamics. IV: Geographical Analysis. V: Pyrological Classification of Landscapes, Sites and Fuel Types. VI: Fire Characteristics: Behavior and Modeling. VII: Ecological Effects of Fire. VIII: Fire, Atmosphere, and Climate Change. Annex I: Understanding Boreal Ecosystems E.W. Ross. Annex II: The International Boreal Forest Research Association (IBFRA) Stand Replacement Fire Working Group. Annex III: Fire Research in the Boreal Forests of Eurasia: A Component of a Global Fire Research Program (IGBP). Index.

Relationships between charcoal particles in air and sediments in west-central Siberia

Production and size of charred particles determine transport and deposition in lakes. Lack of such data is a principal obstacle to interpretation of past fire from charcoal profiles. Our two-part analysis includes a calibration study, to assess charred-particle production and transport during fire, and a study of charred particles in sediment. The calibration step establishes the magnitude and size distribution of particle accumulation from traps during a controlled burn of Pinus sylvewtris forest in west-central Siberia. This high-intensity fire consumed 3.71 kg m-2 of fuels and produced 0.0729 kg m-2 of airborne particles, for an emission factor of 0.02 kg kg-1. Particle flux to the ground was 1 to 3 mm2cm-2 yr-1 inside the burn; it declined sharply within 5 m of the burn edge, and it was variable but without trend to a distance of 60 m. Particle-size distributions were conservative, with a slope of 2 on plots of log frequency versus log diameter, and sediment data suggest this slope may steepen as sources bcome more remote and as large particles are progressively lost due to settling. Deposition from the plume is similar to accumulation rates in sediment, with apparent upward bias in sediments as expected from broad geographic patterns in charcoal distributions. During the mid-Holocene charred-particle accumulation in lake sediments (101 mm2 cm-2 yr-1 was greater than observed in particle traps within the experimental burn. Particles were larger, suggesting nearby sources. Rates decreased by 3800 BP to values lower than average rates in particle traps, and samples were depleted in large particles. Low rates and infrequent large particles indicate sources were distant. Accumulation rates and particle sizes were again high from 3400 to 2800 and from 1400 to 700 BP. Close correspondence between the accumulation rates during the experimental burn and in sediments and particle evidence for source area, as well as their agreement with particle-trap data from the experimental burn, suggest that, in this region, fire may have been more frequent and closer in the mid-Holocene than today. We cannot rule out the possibility, however, that changes in charred particle accumulation also reflect changes in supply of sediment to the core site.

Modeling of carbonaceous particles emitted by boreal and temperate wildfires at northern latitudes

For the first time, a spatial and monthly inventory has been constructed for carbonaceous particles emitted by boreal and temperate wildfires in forests, shrublands, and grasslands, with burned area data statistics, fuel load maps, fire characteristics, and particle emission factors. The time period considered is 1960–1997, and an important year-to-year variability was observed. On average, boreal and temperate vegetation fires represent 4% of global biomass burning, but during extreme years, their contribution may reach 12%, producing 9% and 20% of black carbon (BC) and particulate organic matter (POM), respectively, emitted by worldwide fires. The North American component of the boreal forest fires (Canada and Alaska) represents 4 to 122 Gg C yr-1 of BC and 0.07 to 2.4 Tg yr-1 of POM emitted, whereas the Eurasiatic component (Russia and northern Mongolia) may vary in the 16 to 474 Gg C yr-1 range for BC and between 0.3 and 9.4 Tg yr-1 for POM, with however great uncertainty. Temperate forests in conterminous United States and Europe have a much lower contribution with an average of 11 Gg C yr-1 of BC and 0.2 Tg yr-1 of POM. Grassland fires in Mongolia represent significant BC and POM sources which may reach 62 Gg C and 0.4 Tg, respectively. Finally, an annual average of BC emissions for shrubland fires in both the Mediterranean region and California is 20 Gg C yr-1, with average POM emissions of 0.1 Tg yr-1. These source maps obtained with a high spatial resolution (lox lo) can now be added to previous ones developed for other global carbonaceous aerosol sources (fossil fuel combustion, tropical biomass burning, agricultural and domestic fires) in order to provide global maps of particulate carbon emissions. Taking into account particle injection height in relation with each type of fire, our source map is a useful tool for studying the atmospheric transport and the impact of carbonaceous aerosols in three-dimensional transport and climate models.

International geosphere-biosphere programme/international global atmospheric chemistry SAFARI-92 field experiment: Background and overview

The International Geosphere-Biosphere Programme/International Global Atmospheric Chemistry (IGBP/IGAC) Southern Africa Fire-Atmosphere Research Initiative (SAFARI-92) field experiment was conducted in the 1992 dry season in southern Africa. The objective of the experiment was a comprehensive investigation of the role of vegetation fires, particularly savanna fires, in atmospheric chemistry, climate, and ecology. During SAFARI-92 experimental fires were conducted in Kruger National Park, South Africa, and at some sites in Zambia, in order to study fire behavior and trace gas and aerosol emissions. Regional studies on atmospheric chemistry and meteorology showed that vegetation fires account for a substantial amount of photochemical oxidants and haze over the subcontinent, and that the export of smoke-laden air masses contributed strongly to the ozone burden of the remote atmosphere in the southern tropical Atlantic region. The relationships between fire, soil moisture status, and soil trace gas emissions were investigated for several climatically and chemically important gases. Remote sensing studies showed that advanced very high resolution radiometer/local area coverage (AVHRR/LAC) imagery was valuable for fire monitoring in the region and in combination with biomass models could be used for the estimation of pyrogenic emissions.

Black carbon formation by savanna fires: Measurements and implications for the global carbon cycle

During a field study in southern Africa (Southern African Fire-Atmosphere Research Initiative (SAFARI-92)), black carbon formation was quantified in the residues of savanna fires. The volatilization ratios of C, H, N, and S were determined by measuring their contents in the fuel and residue loads on six experimental sites. The volatilization of sulfur (86±8%) was significantly higher than previously reported. Volatilization of H, N, and S was significantly correlated with that of carbon, enabling us to estimate their volatilization during savanna fires by extrapolation from those of carbon. By partitioning the residues in various fractions (unburned, partially burned, and ash), a strong correlation between the H/C ratio in the residue and the fonnation of black carbon was obtained. The ratio of carbon contained in ash to carbon contained in the unburned and partially burned fraction is introduced as an indicator of the degree of charring. As nitrogen was enriched in the residue, especially in the ash fraction of > 0.63 mm, this indicator may be useful for an assessment of nutrient cycling. We show that the formation of black carbon is dependent on the volatilization of carbon as well as the degree of charring. The ratio of black carbon produced to the carbon exposed to the fire in this field study (0.6-1.5%) was somewhat lower than in experimental fires under laboratory conditions (1.0-1.8%) which may be due to less complete combustion. The average ratio of black carbon in the residue to carbon emitted as CO 2 ranged from 0.7 to 2.0%. Using these ratios together with various estimates of carbon exposed or emitted by savanna fires, the worldwide black carbon fonnation was estimated to be 10-26 Tg C yr -1 with more than 90% of the black carbon remaining on the ground. The formation of this black carbon is a net sink of biospheric carbon and thus of atmospheric CO 2 as well as a source of O 2 .

Crown fire emissions of CO2, CO, H2, CH4, and TNMHC from a dense Jack pine boreal forest fire

Samples of high-intensity crown fire smoke were collected using a helicopter during the International Crown Fire Modeling Experiment near Fort Providence, Northwest Territories, Canada. The samples were analyzed for carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), methane (CH4), and total nonmethane hydrocarbons (TNMHC). CO2− normalized mean emission ratios (ERs) and emission factors (g product/kg fuel burned) were determined for CO2, CO, H2, CH4, and TNMHC. Carbon monoxide production was determined to increase during high-intensity crowning. Unlike CO, a corresponding increase in the production of H2, CH4, and TNMHC during crowning was not detected. This represents the first clear indication that we know of where relative increases in CO production from vegetation fires are not positively correlated with corresponding increases in CH4, H2, and TNMHC production. These results may be important to the atmospheric carbon budget, and to the potential use of CO as a normalizing parameter for boreal forest fire emissions.

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release w ...

Biomass Burning in the Global Environment: First Results from the IGAC/BIBEX Field Campaign STARE/TRACE-A/SAFARI-92

Biomass burning is now recognized as a major source of important trace gases, including CO2, NO2, CO and CH4, and of aerosol particles. It takes on many forms: burning of forested areas for land clearing, extensive burning of grasslands and savannas to sustain grazing lands, burning of harvest debris, and use of biomass fuel for heating.

Impacts of vegetation fire emissions on the environment, human health and security – A global perspective

Air pollution generated by vegetation fire smoke (VFS) is a phenomenon that has influenced the global environment in prehistoric and historic time scales. Although historic evidence of the impacts of VFS on societies is scarce, there are indications that VFS has been a factor that influenced society significantly since the Middle Ages. In recent decades, increasing application of fire as a tool for land-use change has resulted in more frequent occurrence of extended fire and smoke episodes with consequences on human health and security. Some of these events have been associated with droughts that are attributed to inter-annual climate variability or possible consequences of regional climate change. In metropolitan or industrial areas, the impacts of VFS may be coupled with the emission burden from fossil fuel burning and other technogenic sources, resulting in increasing adverse affects on the human population. We review the character, magnitude, and role of pyrogenic gaseous and particle emissions on the composition and functioning of the global atmosphere, human health, and security. Special emphasis is given on radioactive emissions generated by fires burning in peatlands and on terrain contaminated by radionuclides. The transboundary effects of VFS pollution are a driving argument for developing international policies to address the underlying causes for avoiding excessive fire application, and to establish sound fire and smoke management practices and protocols of cooperation in wildland fire management at an international level.