Until now, scientists have assumed that keeping livestock on large steppe grassland contributes to the constantly growing nitrous oxide concentration in the atmosphere and thus to global warming. But now the opposite has been proved: Klaus Butterbach-Bahl’s team of five from the Karlsruher Institute of Technology (KIT) have shown that animals grazing on steppe and prairie areas can actually reduce greenhouse gas emissions. In recognition of their long-term study, the ecosystem specialists have now received the 2013 Erwin Schrödinger Prize, which is endowed with €50,000. The prize is awarded each year by the Stifterverband für die Deutsche Wissenschaft and the Helmholtz Association.
After carbon dioxide and methane, nitrous oxide is the third-biggest contributing gas to the greenhouse effect and climate change. Around 60 percent of nitrous oxide emissions caused by human activity come from agriculture – for example, microbial decomposition of nitrogen-containing excrement from grazing sheep or cattle. Because of this, scientists around the world assumed that keeping animals on steppes and prairies must also contribute to the production of nitrous oxide. However, in a study conducted in Inner Mongolia, China, KIT’s international team of scientists proved that the situation is more complicated than that. Project leader Butterbach-Bahl found that “areas not used for livestock breeding emit much larger amounts of nitrous oxide over the year than steppe areas on which animals are grazing.” The team’s investigations were funded by the German Research Foundation. The other members of the team alongside Butterbach-Bahl were Xunhua Zheng of the Chinese Academy of Sciences, Nicolas Brüggemann, now of Forschungszentrum Jülich, Michael Dannenmann of KIT, and Benjamin Wolf, who is now at Swiss research institute EMPA.
The Stifterverband’s new president Andreas Barner will confer the prize during the annual meeting of the Helmholtz Association in Berlin on 19 September 2013. Jürgen Mlynek, President of the Helmholtz Association, congratulated the prize-winners: “The study makes an impressive contribution to our understanding of the effects of agriculture on global warming. Its focus on a current hot topic means it is sure to have a major impact on ongoing scientific debate about climate change.”
Measuring nitrous oxide emissions is a technically complex procedure, so data are usually only collected over a short period of time during early spring. The Karlsruhe team, however, collected data on nitrous oxide production in the soil over an entire year. “Previous short-term studies ignored the fact that the emission of significant nitrous oxide amounts from steppe soils into the atmosphere is a natural process and most of the natural nitrous oxide emissions take place during the thawing period in spring,” explains Butterbach-Bahl. And it is precisely these emissions that livestock reduce. As the animals graze on the pastureland the grass becomes much shorter. This means that more snow is swept away by the wind, creating a shallower covering of snow. The ground is thus more poorly insulated during the long, cold winter and can therefore be up to 10 °C colder. On top of that, there is less meltwater during the thaw in March, so the ground is dryer. Cold, dry conditions retard microbial activity, and less nitrous oxide is produced. On the basis of their findings, the scientists estimate that previous calculations overestimated nitrous oxide emissions from these areas by around 72 percent. “Our work just shows that much research remains to be done to really understand the sources of atmospheric nitrous oxide,” says Butterbach-Bahl. More livestock farming is not the answer, however, as this would increase methane production. What’s more, overgrazing leads to soil degradation and increased loss of soil carbon.
About the Stifterverband science prize – the Erwin Schrödinger Prize
The Helmholtz Association and Stifterverband für die Deutsche Wissenschaft have conferred the Erwin Schrödinger Prize since 1999. The prize is awarded in recognition of outstanding scientific and technological achievements in areas of convergence between medicine, the natural sciences and engineering. The scientists in the winning team must represent at least two different disciplines. The prize is awarded alternately by the Stifterverband and the Helmholtz Association each year, and the winners are free to decide how to spend the €50,000 prize money. The prize is formally handed over at the Helmholtz Association’s annual meeting.
About the prizewinners
Prof. Klaus-Butterbach-Bahl was the scientific leader of the project team. He is an expert in the field of modelling global environmental change and in identifying and characterising microbial processes. He heads the Bio-Geo-Chemical Processes department at Karlsruhe Institute of Technology’s Institute of Meteorology and Climate Research – Atmosphere Environmental Research (IMK – IFU). KIT is a member of the Helmholtz Association.
Prof. Xunhua Zheng is a globally renowned researcher in the quantification of greenhouse gases from agricultural ecosystems in China. She is a professor at the Chinese Academy of Sciences (CAS) and a member of its Institute of Atmospheric Physics. Zheng was significantly involved with her group in the quantification of nitrous oxide fluxes.
Prof. Nicolas Brüggemann has co-initiated the project and participated in all activities – also on site. Since 2010 he is Professor for Terrestrial Biogeochemistry at the University of Bonn, and leader of the Plant-Soil-Atmosphere Exchange Processes group in the Agrosphere section of the Institute of Bio- and Geosciences at Forschungszentrum Jülich (also a member of the Helmholtz Association). While the study was taking place he was a group leader at the Karlsruhe Institute of Technology’s Institute of Meteorology and Climate Research – Atmosphere Environmental Research (IMK – IFU).
Dr Michael Dannenmann is an internationally renowned expert in the identification and quantification of microbial processes in nitrogen/carbon production, consumption and emissions. He is acting group leader of the Regionalization of Biogenic Trace Gas Emission group at Karlsruhe Institute of Technology’s Institute of Meteorology and Climate Research – Atmosphere Environmental Research (IMK – IFU).
Dr Benjamin Wolf was the leading scientist on site in Inner Mongolia during the entire observation period. While the study was taking place he was a PhD student at the Karlsruhe Institute of Technology’s Institute of Meteorology and Climate Research – Atmosphere Environmental Research (IMK – IFU). He is currently a postdoc at the Swiss Federal Laboratories for Materials Science and Technology (EMPA).
The Helmholtz Association contributes to solving major challenges facing society, science and the economy with top scientific achievements in six research fields: Energy; Earth and Environment; Health; Key Technologies; Structure of Matter; and Aeronautics, Space and Transport. With just under 34,000 employees in 18 research centres and an annual budget of approximately €3.8 billion, the Helmholtz Association is Germany’s largest scientific organisation. Its work follows in the tradition of the great natural scientist Hermann von Helmholtz (1821-1894).
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