October 2020 “Nature” Global nitrous oxide sources and sinks

October 2020 “Nature” Global nitrous oxide sources and sinks

A comprehensive quantification of global nitrous oxide sources and sinks

Tian, H., Xu, R., Canadell, J.G., […], Regnier P., […], Laruelle G.G., Lauerwald R., […], Maavara T. et al.

Nature: link

ULB official communication: link

Yale University video: link

AUBURN, Ala. – Rising nitrous oxide emissions are jeopardizing climate goals and the Paris Accord, a study published in Nature, and led by an Auburn University researcher, has found.

The growing use of nitrogen fertilizers in the production of food worldwide is increasing concentrations of nitrous oxide in the atmosphere—a greenhouse gas 300 times more potent than carbon dioxide—which remains in the atmosphere longer than a human lifetime.

This finding is part of a study co-led by professor Hanqin Tian, director of the International Center for Climate and Global Change Research at Auburn University’s School of Forestry and Wildlife Sciences and Andrew Carnegie Fellow. The study was published today in Nature, the world’s most highly cited interdisciplinary science journal.

Tian co-led an international consortium of scientists from 48 research institutions in 14 countries under the umbrella of the Global Carbon Project and the International Nitrogen Initiative. The objective of the study, titled “A comprehensive quantification of global nitrous oxide sources and sinks,” was to produce the most comprehensive assessment to date of all sources and sinks of the potent greenhouse gas nitrous oxide.

The study points to an alarming trend affecting climate change: Nitrous oxide has risen 20 percent from pre-industrial levels and its growth has accelerated over recent decades due to emissions from various human activities.

“The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,” Tian said. “There is a conflict between the way we are feeding people and stabilizing the climate.”

The study also determined that the largest contributors to global nitrous oxide emissions come from East Asia, South Asia, Africa and South America.

Emissions from synthetic fertilizers dominate releases in China, India and the U.S., while emissions from the application of livestock manure as fertilizer dominates releases in Africa and South America, the study found. The highest growth rates in emissions are found in emerging economies, particularly Brazil, China and India, where crop production and livestock numbers have increased.

The co-authors agreed that the most surprising result of the study was the finding that current trends in nitrous oxide emissions are not compatible with pathways consistent to achieve the climate goals of the Paris Climate Agreement, or the Paris accord.

Signed by 195 nations, the agreement aims to strengthen the global response to the threat of climate change by keeping a global temperature rise in the twenty-first century well below 2 degrees Celsius above pre-industrial levels, and to pursue efforts to limit the temperature rise even further, to 1.5 degrees Celsius.

“Current emissions are tracking global temperature increases above 3 degrees Celsius, twice the temperature target of the Paris accord,” said Robert Jackson, a professor and coauthor from Stanford University and chair of the Global Carbon Project.

News of the last months

News of the last months

During the Covid crisis and the summer period BGEOSYS was very active.

Five new postdocs have joined the team: Maria De La Fuente Ruiz (Fiesta), Nick Hayes (Nutti), Aidin Jabbari (Verify), Ankit Pramanik (Nutti) and Sebastiaan van de Velde (FED-tWIN profile).

Four PhD students have successfully defended their thesis: Alizée Roobaert, Matteo Puglini, Philip Pika and Audrey Plante.

Several new articles were published in prestigious journals .

Consult “staff” , “publications” and “projects” pages to learn more.

August 2020 “Science Advances”

August 2020 “Science Advances”

Widespread energy limitation to life in global subseafloor sediments

J.A. Bradley, S. Arndt, J. P. Amend, E. Burwicz, A. W. Dale, M. Egger and D. E. LaRowe


Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth’s biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation and calculate the power utilization of microbial cells throughout Earth’s Quaternary-age subseafloor sediments. Aerobic respiration, sulfate reduction, and methanogenesis mediate 6.9, 64.5, and 28.6% of global subseafloor organic matter degradation, respectively. The total power utilization of the subseafloor sediment biosphere is 37.3 gigawatts, less than 0.1% of the power produced in the marine photic zone. Aerobic heterotrophs use the largest share of global power (54.5%) with a median power utilization of 2.23 × 10−18 watts per cell, while sulfate reducers and methanogens use 1.08 × 10−19 and 1.50 × 10−20 watts per cell, respectively. Most subseafloor cells subsist at energy fluxes lower than have previously been shown to support life, calling into question the power limit to life.


Publication in “Science” August 2019

Publication in “Science” August 2019

The geologic history of seawater oxygen isotopes from marine iron oxides

Galili N., Shemesh A., Yam R., Brailovsky I., Sela-Adler M., Schuster E.M., Collom C., Bekker A., Planavsky N., Macdonald F.A., Préat A., Rudmin M., Trela W., Sturesson U., Heikoop J.M., Aurell M., Ramajo J. and Halevy I.



The oxygen isotope composition (δ18O) of marine sedimentary rocks has increased by 10 to 15 per mil since Archean time. Interpretation of this trend is hindered by the dual control of temperature and fluid δ18O on the rocks’ isotopic composition. A new δ18O record in marine iron oxides covering the past ~2000 million years shows a similar secular rise. Iron oxide precipitation experiments reveal a weakly temperature-dependent iron oxide–water oxygen isotope fractionation, suggesting that increasing seawater δ18O over time was the primary cause of the long-term rise in δ18O values of marine precipitates. The 18O enrichment may have been driven by an increase in terrestrial sediment cover, a change in the proportion of high- and low-temperature crustal alteration, or a combination of these and other factors.

ARC Project: NuttI

ARC Project: NuttI

Nutrient Factories under the Ice (NuttI): Quantifying the subglacial biogeochemical reactor and its response to climate change

Prof. Sandra Arndt as coordinator (BGeoSys) and Prof. Frank Pattyn (Laboratoire de Glaciologie), are funded for their "Actions de Recherche Concertée-ARC" project: NuttI.

Climate change is amplified in polar regions. As a consequence, ice sheets and glaciers (and in particular the Greenland Ice Sheet) are currently experiencing record melting, resulting in a significant increase of already substantial summer freshwater fluxes to the ocean. While the physical consequences of this freshwater input, as well as its alarming increase have been intensively studied, its biogeochemical dimension remains poorly understood.

The specific objectives of NuttI are to:

  1. develop and test the very first, mechanistic, hydrological-biogeochemical model framework for subglacial environments and, thus, provide novel analytic and predictive capabilities for assessing the consequences of ice sheet retreat
  2. use the newly developed model to quantitatively identify the main hydrological and biogeochemical controls on subglacial carbon and nutrient export under different environmental conditions and over a melt season

More information on NuttI

Cruise in the Baltic Sea: study of the effects of hypoxia

Cruise in the Baltic Sea: study of the effects of hypoxia

From the 18th of June to the 5th of July, Prof. Lei Chou, Nathalie Roevros, Audrey Plante and Hailong Zhang participated to an oceanographic cruise on board of the R.V. BELGICA in the Baltic Sea near Gotland Island. This was organised in collaboration with Prof. Martine Leermakers from the Department of Analytical, Environmental and Geochemistry (AMGC) at the Vrije Universiteit Brussel (VUB).

The deep waters of this area are often hypoxic which have a great influence on the biogeochemical conditions of the water column and sediments.

The objectives are to understand benthic nutrient and trace metal cycling, benthic‐pelagic coupling, diagenetic pathways and the impact of hypoxia on these processes.