ERC FUNDED PROJECTS

Severe droughts in Amazonia in 2005 and 2010 caused widespread loss of carbon from the terrestrial biosphere. This loss, almost twice the annual fossil fuel CO2 emissions in the EU, suggests a large sensitivity of the Amazonian carbon balance to a predicted more intense drought regime in the next decades. This is a dangerous inference though, as there is no scientific consensus on the most basic metrics of Amazonian carbon exchange: the gross primary production (GPP) and its response to moisture deficits in the soil and atmosphere. Measuring them on scales that span the whole Amazon forest was thus far impossible, but in this project I aim to deliver the first observation-based estimate of pan-Amazonian GPP and its drought induced variations. My program builds on two recent breakthroughs in our use of stable isotopes (13C, 17O, 18O) in atmospheric CO2: (1) Our discovery that observed δ¹³C in CO2 in the atmosphere is a quantitative measure for vegetation water-use efficiency over millions of square kilometers, integrating the drought response of individual plants. (2) The possibility to precisely measure the relative ratios of 18O/16O and 17O/16O in CO2, called Δ17O. Anomalous Δ17O values are present in air coming down from the stratosphere, but this anomaly is removed upon contact of CO2 with leaf water inside plant stomata. Hence, observed Δ17O values depend directly on the magnitude of GPP. Both δ¹³C and Δ17O measurements are scarce over the Amazon-basin, and I propose more than 7000 new measurements leveraging an established aircraft monitoring program in Brazil. Quantitative interpretation of these observations will break new ground in our use of stable isotopes to understand climate variations, and is facilitated by our renowned numerical modeling system “CarbonTracker”. My program will answer two burning question in carbon cycle science today: (a) What is the magnitude of GPP in Amazonia? And (b) How does it vary over different intensities of drought?

2 269 689 €

Start date: 2015-09-01, End date: 2020-08-31

Knowledge of the state of the Earth mantle and its temporal evolution is fundamental to a variety of disciplines in Earth Sciences, from the internal dynamics to its many expressions in the geological record (postglacial rebound, sea level change, ore deposit, tectonics or geomagnetic reversals). Mantle convection theory is the centerpiece to unravel the present and past state of the mantle. For the past 40 years considerable efforts have been made to improve the quality of numerical models of mantle convection. However, they are still sparsely used to estimate the convective history of the solid Earth, in comparison to ocean or atmospheric models for weather and climate prediction. The main shortcoming is their inability to successfully produce Earth-like seafloor spreading and continental drift self-consistently. Recent convection models have begun to successfully predict these processes (Coltice et al., Science 336, 335-33, 2012). Such breakthrough opens the opportunity to combine high-level data assimilation methodologies and convection models together with advanced tectonic datasets to retrieve Earth's mantle history. The scope of this project is to produce a new generation of tectonic and convection reconstructions, which are key to improve our understanding and knowledge of the evolution of the solid Earth. The development of sustainable high performance numerical models will set new standards for geodynamic data assimilation. The outcome of the AUGURY project will be a new generation of models crucial to a wide variety of disciplines.

1 994 000 €

Start date: 2014-03-01, End date: 2020-02-29

"Atmospheric aerosol particles have been shown to impact the earth's climate because they scatter and absorb solar radiation (direct effect) and because they can modify the microphysical properties of clouds by acting as cloud condensation nuclei or ice nuclei (indirect effects). Radiative forcing by anthropogenic aerosols remains poorly quantified, thus leading to considerable uncertainty in our understanding of the earth’s climate response to the radiative forcing by greenhouse gases. Black carbon (BC), mostly emitted by anthropogenic combustion processes and biomass burning, is an important component of atmospheric aerosols. Estimates show that BC may be the second strongest contributor (after CO2) to global warming. Adverse health effects due to particulate air pollution have also been associated with traffic-related BC particles. These climate and health effects brought BC emission reductions into the political focus of possible mitigation strategies with immediate and multiple benefits for human well-being. Laboratory experiments aim at the physical and chemical characterisation of BC emissions from diesel engines and biomass burning under controlled conditions. A mobile laboratory equipped with state-of-the-art aerosol sensors will be used to determine the contribution of different BC sources to atmospheric BC loadings, and to investigate the evolution of the relevant BC properties with atmospheric aging during transport from sources to remote areas. The interactions of BC particles with clouds as a function of BC properties will be investigated with in-situ measurements by operating quantitative single particle instruments behind a novel sampling inlet, which makes selective sampling of interstitial, cloud droplet residual or ice crystal residual particles possible. Above experimental studies aim at improving our understanding of BC’s atmospheric life cycle and will be used in model simulations for quantitatively assessing the atmospheric impacts of BC."

1 992 015 €

Start date: 2014-03-01, End date: 2019-02-28

"The eruption of volcanoes appears one of the most unpredictable phenomena on Earth. Yet the situation is rapidly changing. Quantification of the eruptive record constrains what is possible in a given volcanic system. Timing is the hardest part to quantify. The main process triggering an eruption is the refilling of a sub-volcanic magma chamber by a new magma coming from depth. This process results in magma mixing and provokes a time-dependent diffusion of chemical elements. Understanding the time elapsed from mixing to eruption is fundamental to discerning pre-eruptive behaviour of volcanoes to mitigate the huge impact of volcanic eruptions on society and the environment. The CHRONOS project proposes a new method that will cut the Gordian knot of the presently intractable problem of volcanic eruption timing using a surgical approach integrating textural, geochemical and experimental data on magma mixing. I will use the compositional heterogeneity frozen in time in the rocks the same way a broken clock at a crime scene is used to determine the time of the incident. CHRONOS will aim to: 1) be the first study to reproduce magma mixing, by performing unique experiments constrained by natural data and using natural melts, under controlled rheological and fluid-dynamics conditions; 2) obtain unprecedented high-quality data on the time dependence of chemical exchanges during magma mixing; 3) derive empirical relationships linking the extent of chemical exchanges and the mixing timescales; 4) determine timescales of volcanic eruptions combining natural and experimental data. CHRONOS will open a new window on the physico-chemical processes occurring in the days preceding volcanic eruptions providing unprecedented information to build the first inventory of eruption timescales for planet Earth. If these timescales can be linked with geophysical signals occurring prior to eruptions, this inventory will have an immense value, enabling precise prediction of volcanic eruptions."

1 993 813 €

Start date: 2014-05-01, End date: 2019-04-30