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  • 1
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    American Meteorological Society
    In:  Bulletin of the American Meteorological Society, 97 (6). pp. 1069-1072.
    Publication Date: 2019-02-01
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2016-10-05
    Description: One of the controlling factors of net ecosystem exchange that is highly sensitive to changes in climate is fire activity. A model study to describe these controlling factors is validated using multiple proxies to understand fire activity on a continental scale. We present results form a transient integration with the fully coupled Earth System Model (ESM) ECHAM5/MPI-OM1/JSBACH of the Max-Planck-Institute for Meteorology covering the last 6000 years. The model comprises dynamical components for atmosphere, ocean, and biosphere including an approach to simulate fire dynamics. The simulation is analyzed with a focus on land carbon and fire dynamics. A range of observational products are used to constrain the models ability to simulate fire distribution and changes in fire regimes over the course of the last 6000 years. On the global land scale, the model run shows a small decrease of the global mean temperature and a decline in annual precipitation. For the land carbon storage there is a significant decrease. Due to the changes in the orbital parameters with time, regionally the effect on precipitation and temperature is stronger, which results in a shift of the tropical rain belt combined with changes in vegetation. Striking is for example a reduction in the vegetation cover in central East Asia over the last 6000 years with a subsequent decreasing trend in land carbon. Related to climatic changes the fire activity is changing as well. We simulate a reduction of 5% in annual global burned area within the last 6000 years. Regionally, the simulation points out trends in the fire activity corresponding to the changes in vegetation shifts: e.g. there is an increase of 15% in central East Asia and a reduction of about 20% in tropical West Africa in burned area mainly a result of the redistribution of fuel abundance. Simulated changes in fire activity are compared to fire activity records reported in the global charcoal database (Power et al., 2008) and levoglucosan values out of ice cores. As the charcoal data and levoglucosan data show opposite trends, we demonstrate the sensitivity of the modeled and observed trend to the chosen grid boxes of the model domain. Whereas the charcoal sites are biased to North-America and show an opposite trend than the ice-core data from Kilimanjaro, the investigation of levoglucosan data out of remote ice cores (EPICA or NEEM) are additional used to get a global view on the trend in fire activity.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 3
    Publication Date: 2016-10-05
    Description: One of the controlling factors of NEE that is highly sensitive to changes in climate is fire activity. Here we present results form a transient integration with the fully coupled MPI- Earth System Model (MPI-ESM) of the Max-Planck-Institute for Meteorology covering the last 6000 years. The model comprises dynamical components for atmosphere, ocean, and biosphere including an approach to simulate fire dynamics. The simulation is analyzed with a focus on land carbon and fire dynamics. A range of observational products is used to constrain the models ability to simulate fire distribution and changes in fire regimes over the course of the last 6000 years. On the global land scale, the model run shows a small decrease of the global mean temperature and a decline in annual precipitation. For the land carbon storage there is a significant decrease. On the regional scale, the effect on temperature and precipitation due to changes in the orbital parameters with time is much stronger. A shift of the tropical rain belt combined with changes in vegetation is simulated. Striking is for example a reduction in the vegetation cover in central East Asia over the last 6000 years with a subsequent decreasing trend in land carbon. Related to these climatic changes the fire activity is changing as well. We simulate a reduction of 5% in annual global burned area within the last 6000 years. Regionally, the simulation points out trends in the fire activity corresponding to the changes in vegetation shifts: e.g. there is an increase of ~ +15% in central East Asia and a reduction of about 20% in tropical West Africa in burned area mainly a result of the redistribution of fuel abundance. Simulated changes in fire activity are compared to fire activity records reported in the global charcoal database (Power et al., 2008) and levoglucosan values out of ice cores. A special focus of the analysis will lie on an assessment of correlation between fire activity and large-scale climate indexes (e.g. ENSO, NAO). Focusing on the last 100 yrs the modeled variability is checked against a reconstruction of a yearly global fire history (Mouillot et al., 2005). This comparison points out regions with a significant influence of anthropogenic disturbed fires, which are not represented in the ESM, but play a major role in the last few decades.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
    Publication Date: 2016-10-05
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 5
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    In:  [Poster] In: EGU General Assembly 2015, 12.–17.04.2015 , Vienna, Austria .
    Publication Date: 2016-11-11
    Description: Fire is an important process that affects climate through changes in CO2 emissions, albedo, and aerosols (Ward et al. 2012). Fire-history reconstructions from charcoal accumulations in sediment indicate that biomass burning has increased since the Last Glacial Maximum (Power et al. 2008; Marlon et al. 2013). Recent comparisons with transient climate model output suggest that this increase in global ?re activity is linked primarily to variations in temperature and secondarily to variations in precipitation (Daniau et al. 2012). In this study, we discuss the best way to compare global ?re model output with charcoal records. Fire models generate quantitative output for burned area and fire-related emissions of CO2, whereas charcoal data indicate relative changes in biomass burning for specific regions and time periods only. However, models can be used to relate trends in charcoal data to trends in quantitative changes in burned area or fire carbon emissions. Charcoal records are often reported as Z-scores (Power et al. 2008). Since Z-scores are non-linear power transformations of charcoal influxes, we must evaluate if, for example, a two-fold increase in the standardized charcoal reconstruction corresponds to a 2- or 200-fold increase in the area burned. In our study we apply the Z-score metric to the model output. This allows us to test how well the model can quantitatively reproduce the charcoal-based reconstructions and how Z-score metrics affect the statistics of model output. The Global Charcoal Database (GCD version 2.5; www.gpwg.org/gpwgdb.html) is used to determine regional and global paleofire trends from 218 sedimentary charcoal records covering part or all of the last 8 ka BP. To retrieve regional and global composites of changes in fire activity over the Holocene the time series of Z-scores are linearly averaged to achieve regional composites. A coupled climate-carbon cycle model, CLIMBA (Brücher et al. 2014), is used for this study. It consists of the CLIMBER-2 Earth system model of intermediate complexity and the JSBACH land component of the Max Planck Institute Earth System Model. The fire algorithm in JSBACH assumes a constant annual lightning cycle as the sole fire ignition mechanism (Arora and Boer 2005). To eliminate data processing differences as a source for potential discrepancies, the processing of both reconstructed and modeled data, including e.g. normalisation with respect to a given base period and aggregation of time series was done in exactly the same way. Here, we compare the aggregated time series on a hemispheric and regional scale.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 6
    Publication Date: 2016-10-05
    Description: One of the controlling factors of net ecosystem exchange that is highly sensitive to changes in climate is fire activity. A model study to describe these controlling factors is validated using multiple proxies to understand fire activity on a continental scale. We present results form a transient integration with the fully coupled Earth System Model (ESM) ECHAM5/MPI-OM1/JSBACH of the Max-Planck-Institute for Meteorology covering the last 6000 years. The model comprises dynamical components for atmosphere, ocean, and biosphere including an approach to simulate fire dynamics. The simulation is analyzed with a focus on land carbon and fire dynamics. A range of observational products are used to constrain the models ability to simulate fire distribution and changes in fire regimes over the course of the last 6000 years. On the global land scale, the model run shows a small decrease of the global mean temperature and a decline in annual precipitation. For the land carbon storage there is a significant decrease. Due to the changes in the orbital parameters with time, regionally the effect on precipitation and temperature is stronger, which results in a shift of the tropical rain belt combined with changes in vegetation. Striking is for example a reduction in the vegetation cover in central East Asia over the last 6000 years with a subsequent decreasing trend in land carbon. Related to climatic changes the fire activity is changing as well. We simulate a reduction of 5% in annual global burned area within the last 6000 years. Regionally, the simulation points out trends in the fire activity corresponding to the changes in vegetation shifts: e.g. there is an increase of 15% in central East Asia and a reduction of about 20% in tropical West Africa in burned area mainly a result of the redistribution of fuel abundance. Simulated changes in fire activity are compared to fire activity records reported in the global charcoal database (Power et al., 2008) and levoglucosan values out of ice cores. As the charcoal data and levoglucosan data show opposite trends, we demonstrate the sensitivity of the modeled and observed trend to the chosen grid boxes of the model domain. Whereas the charcoal sites are biased to North-America and show an opposite trend than the ice-core data from Kilimanjaro, the investigation of levoglucosan data out of remote ice cores (EPICA or NEEM) are additional used to get a global view on the trend in fire activity.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 7
    Publication Date: 2019-07-13
    Description: Fires have influenced atmospheric composition and climate since the rise of vascular plants, and satellite data has shown the overall global extent of fires. Our knowledge of historic fire emissions has progressively improved over the past decades due mostly to the development of new proxies and the improvement of fire models. Currently there is a suite of proxies including sedimentary charcoal records, measurements of fire-emitted trace gases and black carbon stored in ice and firn, and visibility observations. These proxies provide opportunities to extrapolate emissions estimates based on satellite data starting in 1997, but each proxy has strengths and weaknesses regarding, for example, the spatial and temporal extents over which they are representative. We developed a new historic biomass burning emissions dataset starting in 1750 that merges the satellite record with several existing proxies, and uses the average of six models from the Fire Model Intercomparison Project (FireMIP) protocol to estimate emissions when the available proxies had limited coverage. According to our approach, global biomass burning emissions were relatively constant with 10-year averages varying between 1.8 and 2.3 petagrams of carbon per year. Carbon emissions increased only slightly over the full time period and peaked during the 1990's after which they decreased gradually. There is substantial uncertainty in these estimates and patterns varied depending on choices regarding data representation, especially on regional scales. The observed pattern in fire carbon emissions is for a large part driven by African fires, which accounted for 58 percent of global fire carbon emissions. African fire emissions declined since about 1950 due to conversion of savanna to cropland, and this decrease is partially compensated for by increasing emissions in deforestation zones of South America and Asia. These global fire emissions estimates are mostly suited for global analyses and will be used in the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN46920 , Geoscientific Model Development (ISSN 1991-959X) (e-ISSN 1991-9603); 10; 9; 3329–3357
    Format: text
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  • 8
    Publication Date: 2016-06-01
    Print ISSN: 0003-0007
    Electronic ISSN: 1520-0477
    Topics: Geography , Physics
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  • 9
  • 10
    Publication Date: 2010-06-01
    Description: We use the global atmospheric GCM aerosol model ECHAM5-HAM to asses possible impacts of future air pollution mitigation strategies on climate. Air quality control strategies focus on the reduction of aerosol emissions. Here we investigate the extreme case of a maximum feasible end-of-pipe abatement of aerosols in the near term future (2030) in combination with increasing greenhouse gas (GHG) concentrations. The temperature response of increasing GHG concentrations and reduced aerosol emissions leads to a global annual mean equilibrium temperature response of 2.18 K. When aerosols are maximally abated only in the Industry and Powerplant sector, while other sectors stay with currently enforced regulations, the temperature response is 1.89 K. A maximum feasible abatement applied in the Domestic and Transport sector, while other sectors remain with the current legislation, leads to a temperature response of 1.39 K. Increasing GHG concentrations alone lead to a temperature response of 1.20 K. We also simulate 2–5% increases in global mean precipitation among all scenarios considered, and the hydrological sensitivity is found to be significantly higher for aerosols than for GHGs. Our study, thus highlights the huge potential impact of future air pollution mitigation strategies on climate and supports the need for urgent GHG emission reductions. GHG and aerosol forcings are not independent as both affect and are influenced by changes in the hydrological cycle. However, within the given range of changes in aerosol emissions and GHG concentrations considered in this study, the climate response towards increasing GHG concentrations and decreasing aerosols emissions is additive. ©2009 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s00382-009-0573-0" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 0930-7575
    Electronic ISSN: 1432-0894
    Topics: Geosciences , Physics
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