ERC FUNDED PROJECTS

Arctic sea ice decline is the exponent of the rapidly transforming Arctic climate. The ensuing local and global implications can be understood by studying past climate transitions, yet few methods are available to examine past Arctic sea ice cover, severely restricting our understanding of sea ice in the climate system. The decline in Arctic sea ice cover is a ‘canary in the coalmine’ for the state of our climate, and if greenhouse gas emissions remain unchecked, summer sea ice loss may pass a critical threshold that could drastically transform the Arctic. Because historical observations are limited, it is crucial to have reliable proxies for assessing natural sea ice variability, its stability and sensitivity to climate forcing on different time scales. Current proxies address aspects of sea ice variability, but are limited due to a selective fossil record, preservation effects, regional applicability, or being semi-quantitative. With such restraints on our knowledge about natural variations and drivers, major uncertainties about the future remain. I propose to develop and apply a novel sea ice proxy that exploits genetic information stored in marine sediments, sedimentary ancient DNA (sedaDNA). This innovation uses the genetic signature of phytoplankton communities from surface waters and sea ice as it gets stored in sediments. This wealth of information has not been explored before for reconstructing sea ice conditions. Preliminary results from my cross-disciplinary team indicate that our unconventional approach can provide a detailed, qualitative account of past sea ice ecosystems and quantitative estimates of sea ice parameters. I will address fundamental questions about past Arctic sea ice variability on different timescales, information essential to provide a framework upon which to assess the ecological and socio-economic consequences of a changing Arctic. This new proxy is not limited to sea ice research and can transform the field of paleoceanography.

2 615 858 €

Start date: 2019-08-01, End date: 2024-07-31

Carbonaceous aerosols (organic and black carbon) remain a major unresolved issue in atmospheric science, especially in urban centers, where they are one of the dominant aerosol constituents and among most toxic to human health. The challenge is twofold: first, our understanding of the sources, sinks and physico-chemical properties of the complex mixture of carbonaceous species is still incomplete; and second, the representation of urban heterogeneities in air quality models is inadequate as they are designed for regional applications. The CARB-City project proposes the development of an innovative modeling framework that will address both issues by combining molecular-level chemical constraints and city-scale modeling to achieve the following objectives: (WP1) to develop and apply new chemical parameterizations, constrained by an explicit chemical model, for carbonaceous aerosol formation from urban precursors, and (WP2) to examine whether urban heterogeneities in sources and mixing can enhance non-linearities in chemistry of carbonaceous compounds and modify their predicted composition. The new modeling framework will then be applied (WP3) to quantify the contribution of traditional and emerging urban aerosol precursor sources to chemistry and toxicity of carbonaceous aerosols; and (WP4) to assess the effectiveness of greener-city strategies in removing aerosol pollutants. This work will enhance fundamental scientific understanding as to how key physico-chemical processes control the lifecycle of carbonaceous aerosols in cities, and will improve the predictability of air quality models in terms of composition and toxicity of urban aerosols, and their sensitivity to changes in energy and land use that cities are currently experiencing. The modeling framework will have the required chemical and spatial resolution for assessing human exposure to urban aerosols. This will allow policy makers to optimize urban emission reductions and sustainable urban development.

1 727 009 €

Start date: 2020-01-01, End date: 2024-12-31

Few geophysical phenomena are as spectacular as tropical cyclones, with their eye surrounded by sharp cloudy eyewalls. There are other types of spatially organised convection (convection refers to overturning of air within which clouds are embedded), in fact organised convection is ubiquitous in the tropics. But it is still poorly understood and poorly represented in convective parameterisations of global climate models, despite its strong societal and climatic impact. It is associated with extreme weather, and with dramatic changes of the large scales, including drying of the atmosphere and increased outgoing longwave radiation to space. The latter can have dramatic consequences on tropical energetics, and hence on global climate. Thus, convective organisation could be a key missing ingredient in current estimates of climate sensitivity from climate models. CLUSTER will lead to improved fundamental understanding of convective organisation to help guide and improve convective parameterisations. It is closely related to the World Climate Research Programme (WCRP) grand challenge: Clouds, circulation and climate sensitivity. Grand challenges identify areas of emphasis in the coming decade, targeting specific barriers preventing progress in critical areas of climate science. Until recently, progress on this topic was hindered by high numerical cost and lack of fundamental understanding. Advances in computer power combined with new discoveries based on idealised frameworks, theory and observational findings, make this the ideal time to determine the fundamental processes governing convective organisation in nature. Using a synergy of theory, high-resolution cloud-resolving simulations, and in-situ and satellite observations, CLUSTER will specifically target two feedbacks recently identified as being essential to convective aggregation, and assess their impact on tropical cyclones, large-scale properties including precipitation extremes, and energetics of the tropics.

1 078 021 €

Start date: 2019-06-01, End date: 2024-05-31

Crustal magmatism is periodic on a very wide range of timescales from pulses of continental crustal growth, through formation of granite batholiths, to eruptions from individual volcanic centres. The cause of this periodicity is not understood. I aim to address this long-standing geological problem through a combination of experiments, petrological methods and numerical models via a novel proposal that periodicity arises because of the highly non-linear ( critical ) behaviour of magma crystallinity with temperature in a series of linked crustal magma reservoirs. The ultimate objective is to answer five fundamental questions: " Why is crustal magmatism episodic? " How are large batholiths formed of rather similar magmas over long periods of time? " How do large bodies of eruptible magma develop that can lead to huge, caldera-forming eruptions? " What controls the chemistry of crustal magmas? Why are some compositions over-represented relative to others? " What is the thermal structure beneath volcanic arcs and how does it evolve with time? The project will address these questions through case studies of three contrasted active volcanoes: Nevado de Toluca, Mexico; Soufriere St Vincent, Lesser Antilles; and Mount Pinatubo, Philippines. For each volcano I will use experimental petrology to constrain the phase relations of the most recently erupted magma as a function of pressure, temperature, volatile content and oxygen fugacity in the shallow, sub-volcanic storage region. I will also carry out high-pressure phase equilibria on coeval Mg-rich basaltic rocks from each area with the aim of constraining the lower crustal conditions under which the shallow magmas were generated and use diffusion chronometry to constrain the frequency of magmatic pulses in the sub-volcanic reservoirs. The project will result in a quantum leap forwards in how experimental and observational petrology can be used to understand magmatic behaviour beneath hazardous volcanoes

2 959 518 €

Start date: 2010-04-01, End date: 2015-03-31