BER Research Highlights

Search Date: August 16, 2017

5 Records match the search term(s):


November 02, 2009

Tree Mortality and Insights from a Decade of Climate Change Research

Ongoing global climatic change is expected to result in longer and more frequent droughts. Recent drought in the western United States has been associated with widespread mortality of pine trees, but because the mechanism of action has been unclear it has been impossible to realistically account for such mortality in global climate models. Now, after 10 years of DOE-sponsored research, it has been determined that long-term drought reduces photosynthesis (carbon assimilation) in pine trees to such an extent that they become "carbon starved." As a result, they are not able to ward off other stresses, such as attack by bark beetles. This new insight into the mechanism of action of drought on tree health will allow global climate models to appropriately account for potential ecological effects of climatic change.

Reference: Breshears, D.B., Myers O.B., Meyer, C.W., Barnes, F.J., Zou, C.B., Allen, C.D., McDowell, N.G., Pockman, W.T.. (2009) Tree die-off in response to global change-type drought: mortality insights from a decade of plant water potential measurements. Frontiers in Ecology and the Environment 7:185-189.

Contact: Jeffrey S. Amthor, SC-23.1, (301) 903-2507
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Division: SC-23.1 Climate and Environmental Sciences Division, BER


October 19, 2009

Adding another Century to the Central European Temperature Record by Removing Early Instrumental Warm-Bias - A Windfall for Global Change Research

Preindustrial surface air temperature records contain biases that make their use for global change research difficult. Understanding and removing those biases would give scientists access to records prior to 1850, broadening current temperature records to a multi-centennial scale. DOE-funded scientist Phil Jones (University of East Anglia in Norwich, UK) and his colleagues have succeeded in creating an instrumental temperature record for the Greater Alpine Region (GAR) in central Europe beginning in the year 1760 by accounting for changes in how instruments were inadequately protected from direct sunlight prior to 1850-1870, when new screening procedures were put in place. Lack of adequate protection caused temperatures in the summer to be biased warm and those in the winter to be biased cold. Removal of those systematic errors was the key to creating this valuable, new, expanded data resource. The results also have broader implications for the calibration of historical proxy climatic data in the region such as tree ring indices and documentation of grape harvest dates.

Reference: Böhm, R., P. D. Jones, J. Hiebl, D. Frank, M. Brunetti, and M. Maugeri. 2009. "The Early Instrumental Warm-Bias: A Solution for Long Central European Temperature Series, 1760-2007," Climatic Change 101(1–2), 41–67. DOI: 10.1007/s10584-009-9649-4. (Reference link)

Contact: Anjuli Bamzai, SC-23.1, (301) 903-0294, Renu Joseph, SC-23.1, (301) 903-9237
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Division: SC-23.1 Climate and Environmental Sciences Division, BER


April 06, 2009

Climate-Relevant Isoprene Chemical Pathways Uncovered

In spite of their many positive attributes, including removing carbon from the atmosphere, some trees also contribute to the challenges of climate change. Many deciduous trees emit isoprene (2-methyl-1,3-butadiene, C5H8) during daylight hours, a major organic carbon compound  accounting for up to 2% of the carbon fixed by those plants and about one third of total volatile organic compounds (VOC) emissions. DOE research has previously demonstrated that isoprene oxidation may contribute significantly to the global aerosol burden with impacts on climate forcing and ozone production. A recent study by this same group described isoprene photooxidation and developed a detailed mechanism, including branching ratios and yields, for the compounds identified. The authors summarize the most important features of this mechanism in a scheme appropriate for use in global chemical transport models. The impact of this chemistry is important in the light of the potential for significant changes in isoprene emissions caused by climate change  and changes in land use.

Reference: F. Paulot, J. D. Crounse, H. G. Kjaergaard, J. H. Kroll, J. H. Seinfeld, and P. O. Wennberg (2009), Isoprene photooxidation: new insights into the production of acids and organic nitrates, Atmos. Chem. Phys., 9, 1479-1501.

Contact: Ashley Williamson, SC-23.1, (301) 903-3120
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Division: SC-23.1 Climate and Environmental Sciences Division, BER


March 16, 2009

Estimating Fossil Energy-based CO2 Emissions from U.S. Croplands

DOE supports research to understand mechanisms of carbon sequestration in managed ecosystems. An important part of that research is knowing the sources of carbon emissions. Scientists from Oak Ridge National Laboratory report a method to estimate both on- and off-site fossil energy-based CO2 emissions (FCE) associated with crop production. FCE was found to differ by crop and region because of changes in energy requirements for crop production driven by environmental differences (e.g., soil texture, soil chemistry, and climate). Changes in policies (e.g., farm bills) and abrupt changes in annual weather patterns (e.g., droughts and wet years) have also resulted in annual shifts in FCE. This new method is important because estimates of fossil-fuel consumption for cropping practices and the associated CO2 emissions enable (1) monitoring of energy and emissions with changes in land management and (2) calculation and balancing of regional and national carbon budgets.

Reference:  Nelson, R.G., C.M. Hellwinckel, C.C. Brandt, T.O. West, D.G. De La Torre Ugarte, G. Marland. 2009. Energy Use and Carbon Dioxide Emissions from Cropland Production in the United States, 1990-2004. Journal of Environmental Quality 38: 418-425.

Contact: Mike Kuperberg, SC-23.1, (301) 903-3511; Roger Dahlman, SC-23.1, (301) 903-4951
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Division: SC-23.1 Climate and Environmental Sciences Division, BER


February 23, 2009

DOE Terrestrial Carbon Researcher Named Georgia Regents' Professor

Professor Monique Leclerc, of the University of Georgia's Crop and Soil Sciences Department, has been named a State of Georgia Regents' Professor. Regents' Professors are faculty members whose scholarship or creative activity is recognized both nationally and internationally as innovative and pace-setting. Regents' Professors receive a permanent increase in salary and a yearly academic support account for the duration of the professorship. Professor Leclerc is an investigator in DOE's terrestrial carbon program, studying the role of vegetation-atmosphere exchange of gases such as carbon dioxide, water, and sulfur dioxide in climate change. This exchange of gases is regulated by a number of factors, including source-sink strengths of those gases and the structure of the turbulent flow within the vegetation canopy.

Contact: Mike Kuperberg/Roger Dahlman, SC-23.1, (301) 903-3511 / (301) 903-4951
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Division: SC-23.1 Climate and Environmental Sciences Division, BER