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(July 8-19, 2019)

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Union lectures


Wednesday, 24 June

10:30    IUGG: Yuan T. Lee (Academy Sinica, Taipei, China)
11:00    IAGA: Janet Kozyra (University of Michigan, USA)
11:30    IAHS: Dominic Mazvimavi (University of the Western Cape, South Africa)

Friday, 26 June

10:30    IACS: Jonathan Gregory (University of Reading and Met Office, UK)
11:00    IASPEI: Raul Madariaga (ENS, Paris, France)
11:30    IAVCEI: Thomas J. Casadevall (USGS, Denver, Colorado, USA)

Monday, 29 June

10:30    IAG: Harald Schuh (GFZ, Potsdam, Germany)
11:00    IAMAS: Laura Gallardo Klenner (Universidad de Chile, Santiago, Chile)
11:30    IAPSO: Nicolas Gruber (ETH Zürich, Switzerland)


Transformation of Human Society for Sustainable Future

Yuan T. Lee
Academy Sinica, Taipei, China

The train of human development is going in the wrong direction, driven chiefly by rising global population and their relentless pursuit of faster growth and more consumption. From here on, the emerging regions led by Asia will be the main drivers. How they choose to develop will largely determine the fate of our world. We must work closely with them to steer in a far more sustainable direction, by fundamentally transforming the way we think about, and go about, human development. Otherwise, what lie ahead will not be prosperity, but catastrophe.

Yuan T. Lee

Born in Taiwan in 1936, Yuan T. Lee received his B.S. degree from the National Taiwan University in 1959 and Doctorate from UC Berkeley in 1965. After working with Professor Mahan at Berkeley and Professor Herschbach at Harvard as a post-doctoral fellow, he was appointed Assistant Professor at the University of Chicago in 1968. He returned to Berkeley as Professor of Chemistry in 1974. He was University Professor and Principal Investigator at the Lawrence Berkeley Laboratory, UC Berkeley, before he returned to Taiwan to serve as the President of Academia Sinica from 1994 to 2006. He was elected President of the International Council for Science (ICSU) in 2008 and served from 2011 to 2014. He has received numerous awards and honors, including the 1986 Nobel Prize in Chemistry, the U.S. National Medal of Science, Faraday Medal from the Royal Chemical Society of Great Britain, the Jawaharlal Nehru Birth Centenary Medal from India, the Ettore Majorana-Erice-Science for Peace Prize from the Ettore Majorana Foundation and Centre for Scientific Culture of Italy, and Kolos Prize and Medal from Poland. He has received Doctor Honoris Causa from 40 universities and is an elected member of various academies throughout the world.

Aside from his scientific interests in the elucidation of dynamics of chemical reactions and photochemical processes, he also directed much of his attention to the advancement of international scientific developments and to the promotion of general public affairs. He has served as advisory board member on numerous national and international organizations, including US Department of Energy, Welch Foundation, Chief Advisor of the Science and Technology Advisory Group to the Prime Minister of Taiwan, International Scientific Council of the Israeli-Palestinian Science Organization, Science and Technology in Society Forum, RIKEN, and Okinawa Institute of Science and Technology in Japan.

The Whole-System Approach to Extreme Space Weather

Janet U. Kozyra
National Science Foundation
on leave from University of Michigan, Department of Atmospheric, Oceanic and Space Sciences

The whole-system investigation of extreme events has emerged as an important research area in a variety of scientific disciplines. A need to understand extreme space weather motivates a similar approach. A space storm involves all major components of the Sun-Earth system - the Sun, heliosphere, magnetosphere, ionosphere and upper atmosphere, and each is a system in its own right. The storm starts when eruptions on the Sun eject clouds of electrically charged gas and strong magnetic fields into space. Some of these clouds are harmless while others can penetrate into and disrupt the space environment around Earth, resulting at times in damage to satellites in space and power grids on Earth. In principle, the whole-system approach makes it possible to start with an extreme feature and then track back through the Sun-Earth system to identify the environmental conditions and interacting physical processes that produced it.

This presentation addresses the following question. What new information (if any) is actually added by a whole-system approach to the study of space storms as opposed to the study of individual components and smaller sub-systems? To carry out this major study requires combining all available satellite observations in regions from Sun to Earth with linked global models and enlisting a large group of interested collaborators with expertise covering all system components, data sets, and global models. The subject selected for this interdisciplinary study was an anomalous space storm on 21 January 2005 that in some ways resembled a super-storm and in others a moderate event. Features associated with each of the Sun-Earth system components were studied during this event and results published in the literature. Despite this, the whole-system approach expanded on these more focused studies revealing new details of the event, in particular, that rare dense solar filament material significantly modified the magnetic cloud structure on its way to Earth, and entered the magnetosphere. The presence of this material and the compression of the magnetosphere by the associated high dynamic pressure were linked to unusual (and at times extreme) features throughout the system. This global view complemented the information from the more focused studies, completing them by showing how the individual components interacted within the system, and feeding back with new questions generated as a direct result of the different perspective this view offered.

Janet U. Kozyra

Janet U. Kozyra is an Emeritus Collegiate Research Professor at the University of Michigan on a leave of absence and currently serving as Program Director for the Magnetospheric Physics Program in the Geosciences Directorate at the National Science Foundation. Over her career she has been a science team member on four different satellite missions exploring geospace and connected regions in the upper atmosphere.  Her most recent scientific focus is on the web of interconnected processes that link the Sun to the upper atmosphere resulting in a rich variety of space weather effects.  This interest drove her to co-chair the international Climate and Weather of the Sun-Earth System (CAWSES-I) Space Weather and Applications Panel (2002-2008), and the CAWSES-II e-Science and Cyber-infrastructure Working Group (2009-2013).  As part of this effort, she was the lead organizer of an interdisciplinary virtual conference with 270 participants from 21 different countries that was co-sponsored by NASA’s Living with a Star Program and the National Science Foundation, as well as organizing multiple international and interdisciplinary observational campaigns for the CAWSES program. Throughout her career, she participated in a variety of strategic planning committees for U.S. national programs in Solar and Space Research, including: the National Research Council decadal surveys of Solar and Space Physics in 2002 and 2012, NASA Heliophysics Roadmap subcommittees in 2002 and 2013, NASA’s "Living with a Star Targeted Research & Technology" Program Definition Team in 2003, NSF’s GeoVision Working Group in 2006-2008 and the NSF CEDAR New Dimensions Strategic Planning Committee in 2009.  All of these resulted in strategic documents aimed at maximizing science returns from federally funded programs while moving forward on science frontiers. In addition, she served on external advisory committees for Space Weather Operations (SWO) at NOAA (2001), Los Alamos National Lab Institute of Geophysics and Planetary Physics (1999-2003), NSF’s Center for Integrated Space Weather Modeling (CISM) (2003-2012), British Antarctic Survey (2007), and the National Center for Atmospheric Research (NCAR)/High Altitude Observatory (2012).  In 2013, she was elected to the Board of Trustees of the University Corporation for Atmospheric Research (UCAR), a consortium of Universities that manages NCAR, but resigned to begin work at the National Science Foundation in 2015.

Challenges of Educating Hydrologists for the Global South; the Case of southern Africa

Dominic Mazvimavi
Institute for Water Studies, University of the Western Cape

The southern Africa region has limited trained personnel in almost all fields including hydrology. Due to the limited number of hydrologists in each country, a singly hydrologist is often expected to contribute towards the solution of a diverse range of hydrological problems. These problems range from the assessment of the available water resources in both gauged and ungauged river basins, estimation of design floods for various purposes (e.g. stormwater drainage, spillways, floodlines for land use planning), river flow forecasting and prediction, assessment of environmental flow requirements, determination of appropriate water allocation, reservoir yield analysis, formulation of policies and guidelines for water resources management. Water resources management in southern Africa is either done by a central national agency or a river basin authority. For most countries, the national agency will not have more than 5-10 trained hydrologists, while river basin authorities may have 1-2 trained hydrologists who are expected to assist in solving diverse water resources management problems. The problem of the limited number of trained hydrologists is worsened by the rapid staff turnover resulting in limited mentoring of young hydrologists. It is not uncommon to find a newly graduated hydrologist being required to undertake hydrological assessments that elsewhere would require considerable years of mentoring. The need to have trained hydrologists capable of solving diverse problems in a rapidly changing environment and with limited resources, raises the questions regarding whether the hydrology education offered in southern Africa adequately prepares hydrologists for the challenges they will encounter.

Most of the practising hydrologists with undergraduate degrees obtained their training as part of their civil/irrigation engineering, geography, geology and environmental science degree programmes. During the last 10 years, few undergraduate hydrology and water resources management programmes have been started. Very few universities offer postgraduate university programmes in hydrology in southern Africa. A considerable number of hydrologists obtained qualifications in Europe and the USA. The curriculum of the hydrology education in southern Africa tends to mirror that in Europe and the USA, and using the same textbooks. Water resources management agencies in the developed countries have matured over the years, and each agency will have several hydrologists trained in the various sub-disciplines of hydrology. Since a southern African hydrologist is expected to solve diverse problems in a rapidly changing environment and with limited resources, the adoption of a curriculum that mirrors that in developed countries is questionable. Exercises used to teach various aspects of hydrology often assume stationarity, yet the hydrological landscape in southern Africa is changing.

There has been a significant increase in research activity during the last 20 years in southern Africa as is evident from the number of papers published. However, the lack of national funding in most of the countries results in most of the research being based on research priorities of the external funding agencies. Thus considerable knowledge gaps exist and constrain effective water resources management. The limited research being done in parts of southern Africa has not impacted on practice in hydrology. Significant problems in the transfer and translation of knowledge exist. Consequently, practising hydrologists continue to use empirical methods developed over 40 years ago for different environmental conditions. This raises the issue of the role of hydrology education in translating research results into practice.

The presentation will examine the above challenges in the education of hydrologists in southern Africa. The presentation will examine whether hydrology education in southern Africa is developing the knowledge and skills required to solve the diverse water resources management problems in the region. Suggestions for improving hydrology education in this region will also be presented.

Dominic Mazvimavi

Dominic Mazvimavi is a Professor of Water and Environmental Sciences in the Department of Earth Sciences, and the Director of the Institute for Water Studies at the University of the Western Cape in South Africa. He obtained a PhD in Hydrology from the Wageningen University and the then International Institute of Geo-information Science and Earth Observation in the Netherlands, MSc in Hydrology from the Vrije Universiteit Brussel, Belgium. For his undergraduate studies, he majored on Geography with Botany and Zoology as minors. After completing his undergraduate studies, he worked as hydrologist for 5 years in the Ministry of Water Resources and Development in Zimbabwe. From 1991 to 1992 he was involved in reviewing and improving the hydrological monitoring system of the Zambezi River basin. Prof Mazvimavi was a member of the academic staff in the Department of Geography at the University of Zimbabwe from 1988 to 2004 teaching mainly hydrology. From 2005 to 2008 he was a Senior Researcher at the Okavango Research Institute of the University of Botswana. While at the Okavango Research Institute, Dominic Mazvimavi led a multi-disciplinary study focusing on the environmental flow assessment of the Okavango River, a transboundary river basin covering parts of Angola, Botswana and Namibia. Dominic Mazvimavi’s research interests are on the assessment of water resources of ungauged river basins, analysis of hydrological time series for change, hydrological effects of land use change, and determining influences of riparian and non-riparian wetlands on hydrological responses.

Prof Mazvimavi has served as a Managing Guest Editor for the Journal of the Physics and Chemistry of the Earth, Associate Editor for the International Journal of Applied Earth Observation and Geoinformation, and Hydrology and Earth System Sciences Journal. He is a founding member of Waternet, a Southern African Development Community (SADC) regional capacity building network of over 70 institutions focusing on research and training on integrated water resources management (IWRM). This network which was started in 2000 runs a regional master’s programme on IWRM.

Sea Level Change in the Anthropocene

Jonathan Gregory
University of Reading and Met Office, UK

The rate of global mean sea level rise (GMSLR) has accelerated during the last two centuries, from the order of magnitude of 0.1 mm yr-1 during the late Holocene, to about 1.5 mm yr-1 for 1901-1990, with ocean thermal expansion and glacier mass loss being probably the dominant contributors. During the last couple of decades the rate of rise has been larger, at around about 3 mm yr-1, because of increased radiative forcing of climate change, and increased ice-sheet outflow induced by warming of the immediately adjacent ocean. Ocean thermal expansion is the largest contributor to projections of GMSLR during the 21st century. For a given scenario, the range of projections for this component relates to uncertainty in simulating the processes of heat uptake into the ocean interior. Climate models also exhibit substantial disagreement in the geographical pattern of sea level change due to ocean density and circulation change. Larger uncertainty in projections of GMSLR comes from the land-ice contributions, especially ice-sheet dynamical change. These contributions also lead to substantial uncertainty in regional sea-level projections, through their effect on gravity and the solid Earth. Until the middle of the 21st century, projections of GMSLR under various scenarios of greenhouse-gas emissions have a small spread, because of the time-integrating characteristic of GMSLR. However by 2100 the rate of GMSLR for a scenario of high emissions could approach the average rates that occurred during the last deglaciation, whereas for a strong emissions mitigation scenario it could stabilise at rates similar to those of the early 21st century. In either case, GMSLR will continue for many subsequent centuries, because of the long timescales of ice-sheet change and deep-ocean warming, and could be partly irreversible.

Jonathan Gregory

Jonathan Gregory joined the Met Office Hadley Centre soon after it opened in 1990, following a PhD in particle physics and a year at the Climatic Research Unit of the University of East Anglia. He is presently a senior climate research scientist of the National Centre for Atmospheric Science at the University of Reading, a professor in the Department of Meteorology, and a Met Office Fellow in climate change research at the Hadley Centre. He was a coordinating lead author of the sea level chapter of the Third Assessment Report of Working Group I of the Intergovernmental Panel on Climate Change, a lead author of the ocean observations and projections chapters of the Fourth Assessment Report, and a lead author of sea level chapter of the Fifth Assessment Report. In 2009 he was awarded an Advanced Grant by the European Research Council for research on sea-level change. His recent interests also include climate sensitivity and radiative forcing, land ice response to past and future climate change, ocean heat uptake and changes in the Atlantic Ocean meridional overturning circulation.

Earthquake Dynamics and Seismic Radiation

Raul Madariaga
ENS, Paris, France

In the 1960s, kinematic models of earthquakes were proposed based on observations of seismic radiation and directivity. Almost simultaneously Kostrov and others developed earthquake models based on fracture mechanics and the state of stress on faults. The synthesis of both approaches is the radiation model proposed by Brune in 1970, which showed that far field spectra had several universal properties. The low and high frequency properties of Brune's model were well explained by the properties of seismic radiation from fracture dynamic.

An equivalent model does not exist for near field records. These are most often modelled as kinematic ruptures that do not satisfy mechanical constraints like conservation of energy, finite stress drops, etc. An alternative approach to properly model near field records is to model them with dynamic fracture models that are simple and robust. Fitting observations with dynamic models is a very non-linear problem that can only be solved with advanced inversion techniques. These are expensive but quite accessible for modern parallel computers. As it is well known dynamic inversion is not unique, but extreme models can be inverted from a set of observed seismograms. These inversions show that events of different origins: intermediate depth, shallow strike slip and subduction zones share many common features and that as proposed by Aki, they statistically satisfy rather simple scaling laws. The most important from the point of view of dynamics is that energy release rate scales with earthquake size. A similar model may explain some slow earthquakes, events whose rupture velocity has not reached speeds comparable to that of seismic waves.

Comparing the spectra of observed and modelled spectra we find the central part of the synthetic spectra reproduce very well the observed ones with many characteristics that recall Brune's spectra. Corner frequency varies from station to station depending on the ratio of available to fracture energy (kappa)., The challenge now is to produce dynamic models that satisfy observations in the high frequency range where waves present significant complexity. To be presented to the 2015 IUGG meeting in Prague.

Raul Madariaga

Raul Ivan Madariaga is professor emeritus in the Department of Geosciences of Ecole Normale Superieure de Paris. He obtained a degree of Civil engineering from the University of Chile in 1967 and a PhD in geophysics from the Massachusetts Institute of Technology in 1972. After a brief stay at the University of Chile from 1971-1973, he became a researcher at MIT’s Earth and Planetary Sciences from 1974-1977. In 1977 he moved to France where he became a professor of Geophysics at the University Paris 7 and the Institut de Physique du Globe (IPGP). In 1998 he moved as a distinguished professor at Ecole Normale Superieure (ENS), where he is still working. In France he was the head of the Seismological laboratory of IPGP from 1985 to 1996 and at ENS he chaired the Geology Laboratory from 2000 to 2006. Raul became a Fellow of the American Geophysical Union (1991) and the Senior Member of the Institut Universitaire de France (1993-1998). He received several awards, among them the Prix Antoine D'Abbadie de l'Académie des Sciences (1992), Grand medal of the Rectorate of the University of Chile in Santiago (1998), Stephan Mueller Medal of the European Geophysical Society (1999) and, finally, the Harry F. Reid Medal of the Seismological Society of America (2004).
He is the authors of two books: Madariaga, R. and G. Perrier, Les Tremblements de Terre, 260 pp., Les Editions du CNRS, 1991 and Udias, A. R. Madariaga, E. Buforn, Source Mechanisms of Earthquakes, Cambridge University Press, 2014. He has authored more than 150 papers in peer reviewed journals. His most cited publication is Dynamics of an expanding circular fault. Bull. Seism.Soc. Am., 65, 163-182, 1976.

Volcanic Ash and Aviation Safety

Thomas J. Casadevall
U.S. Geological Survey, Denver, Colorado, USA

Since the early 1980s, jet-powered aircraft have experienced more than 140 damaging encounters while flying through clouds of volcanic ash from explosively erupting volcanoes. Each year, from 6 to 12 volcanic eruptions inject volcanic ash and associated gases into the upper atmosphere (>30,000 feet) where jet-powered aircraft fly.   More than a dozen of these encounters have involved temporary in-flight loss of engine power. Total damage costs to aircraft from more than 30 years of encounters have totaled more than $200 million US dollars. In addition to in-flight damages, economic losses due to flight delays and cancellations, re-routing of flights, and airport closures from volcanic ash has exceeded $2 billion dollars, most of which was due to the April-May 2010 eruptions of Eyjafjallajokull volcano, Iceland.

To mitigate the hazard presented by volcanic ash the international volcanological, aeronautical, and meteorological communities have worked together to ensure continued safety of flight. Since the late 1980s, several international coordination bodies including the International Civil Aviation Organization, the World Meteorological Organization, the World Organization of Volcano Observatories, the Airline Pilots Association, and the International Air Transport Association, as well as a large number of regional and national aviation organizations have worked together to improve the detection, tracking, and coordination of information about volcanic eruptions to minimize the effects of explosive volcanic eruptions to air traffic on a global scale.

In addition to the improved coordination and communication about volcanic activity, there has been increased training of pilots and air traffic coordinating bodies to make them aware of the ash hazard and how to react in the event of an encounter.

The global aeronautical and volcanological communities continue to look at multiple efforts to improve air safety and minimize the effects of volcanic ash on safe air travel. Following the eruption of Eyjafjallajokull volcano in April-May 2010, there has been increased effort to determine the dosage (concentration and exposure time) of volcanic ash which can damage aircraft. These efforts also include the development and installation of on-board, in-flight ash detection devices, to improvements in remote sensing of volcanic activity and ash cloud generation and movement, to improvements in computer modeling of ash transport and dispersion.

Thomas J. Casadevall

Tom Casadevall is a Scientist Emeritus with the U.S. Geological Survey in Denver, Colorado.  His scientific interests focus on active volcanism and the related hazards to people and aviation operations, and on Geologic Heritage with an emphasis on Protected Volcanic Landscapes. From 1996 through 2008, Tom served in the Office of the Director, USGS.  From 1978 to 1996, he worked as a geologist with the USGS Volcano Hazards Program, stationed at the Hawaiian Volcano Observatory, the Cascades Volcano Observatory, and in Denver, Colorado.  From 1985 through 1988 he was Advisory Volcanologist to the Volcanological Survey of Indonesia and resided in Java, Indonesia. As past-chief of the project on Volcanic Hazards and Aviation Safety, he coordinated USGS activities with other Federal agencies and non-governmental groups in the area of aviation safety.  He was instrumental in organizing the First International Sympo¬sium on Volcanic Ash and Aviation Safety, held in 1991, which was recognized by the aviation industry as the first coordinated exchange of information on the threat that volcanoes poses to air safety. In 1977-1978 he was a faculty member of the Escuela Politecnica Nacional in Quito, Ecuador.  In 1976 he was a National Research Council post-doctoral research fellow with the USGS.  From 1969 to 1972, he worked for in the mineral exploration industry as a geologist exploring for base metals in the western United States and in 1974 he worked as a production geologist in the Sunnyside gold mine, Silverton, Colorado. He currently serves as the past-Chair of the U.S. National Committee of the International Union of Geological Sciences (IUGS).  His honors and awards include the Department of the Interior’s Superior Service Award in 1994 and Meritorious Service Award in 2000; the 2006 Service to America Citizen Award; in 2006 he was awarded the Meritorious Presidential Rank Award. Dr. Casadevall holds a Bachelor of Arts degree (1969) in Geology from Beloit College, Wisconsin; he earned a Master of Arts degree (1974) in Geology and a Ph.D. (1976) in Geochemistry from the Pennsylvania State University. 

Contributions of Geodesy to Monitoring Natural Hazards and Global Change

Harald Schuh
GFZ, Potsdam, Germany

The definition and realization of precise and stable reference frames play an important role in modern geodesy, as they are required when we want to monitor changes on the Earth such as plate tectonics or global sea level rise. An overview of the various natural hazards and global change phenomena that can be observed by geodetic techniques will be given. Depending on the spatial scale, various types of measurements can be used, from space geodetic techniques such as GNSS (Global Navigation Satellite Systems), SLR (Satellite Laser Ranging), VLBI (Very Long Baseline Interferometry), and DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), to local measurements by geodetic surveying instruments. All these techniques are combined in GGOS, the Global Geodetic Observing System of the IAG (International Association of Geodesy), and the concept of this integrative enterprise will be described. Case studies will be presented that document the essential role of precise geodetic data, accurate analysis methods, and realistic mathematical and physical models.

Harald Schuh

Prof. Dr. Dr. h.c. Harald Schuh is the elected Vice-President of the International Association of Geodesy (IAG), Past President of the IAU commission 19 “Rotation of the Earth”, and was the Chair of the International VLBI Service for Geodesy and Astrometry (IVS) from 2007 to 2013. He has engaged in space geodetic research for more than 30 years with special focus on VLBI (Very Long Baseline Interferometry) and Earth rotation. Since 2012, he is the Director of Department 1 “Geodesy and Remote Sensing” at GFZ German Research Centre for Geosciences in Potsdam, Germany, and professor for “Satellite Geodesy” at the Technical University Berlin. Harald Schuh is author or co-author of about 350 publications and editor of more than one dozen of scientific books and proceedings with the main subjects VLBI, Earth rotation, geodynamics, geodetic reference frames, troposphere, and ionosphere.

Atmospheric Chemistry in the Anthropocene

Laura Gallardo
University of Chile

The anthropocene poses new challenges to the atmospheric chemistry community.  There are challenges linked to the fundamental understanding of processes, to the development and maintenance of observational instruments and systems (including models), and to the complexities of the intricate interactions among the climate system components, including human activities. For instance: how do carbonaceous aerosols evolve in the atmosphere becoming more or less absorbing or hydrophilic?; how will our warming planet alter the distribution of ozone and consequently the oxidative capacity of the atmosphere?; how important are halogens for tropospheric ozone in coastal cities?; how do we best observe the changing chemistry of the Earth’s atmosphere?, etc. Such challenges may be considered “old” as they reflect the endeavor of science and research. However, they occur in a fast changing world, under increasing pressure for finding answers and solutions, which leads to stresses regarding science organization and funding. But also to opportunities to explore new perspectives, involve new people, particularly in the developing world, and finding new paradigms. In this presentation, I will illustrate these issues addressing current challenges in the over and around the South Pacific Ocean.

Laura Gallardo

Laura Gallardo is an Associate Professor at the Geophysics Department (DGF), University of Chile, and she is the Director for the Center of Excellence for Climate and Resilience Research. She got a PhD in Chemical Meteorology at Stockholm University (MISU) in 1996 working on lightning and emissions of oxidized nitrogen under the guidance of Prof. Henning Rodhe. She returned to her home land Chile in 1997 where she worked as an expert advisor for National Commission for the Environment (now Ministry for the Environment) between 1997 and 2001, leading the first regional scale dispersion modeling studies, with emphasis on oxidized sulfur from copper smelting. In early 2002 she got a researcher position at the Center for Mathematical Modeling (CMM), where she begun studies on inverse modeling applications for constraining city-scale emission inventories, data assimilation and optimal network design. In December 2007, she got a permanent position at DGF. Her research  interests are broad and cover atmospheric modeling and data assimilation, air quality in mega cities, and lately short-lived climate forcers. She has been the leader for a scientific network and project studying South American Megacities (SAEMC, 2006-2012). Currently she acts as Director for the Center for Climate and Resilience Research (CR2), a center of excellence intended to deepen our understanding of climate system, its natural and anthropogenic changes and its consequences on society. She has served as a member of the Scientific Committee of the International Global Atmospheric of Chemistry (IGAC) for the period 2003-2009, and as a member of the international Commission for Atmospheric Chemistry and Global Pollution (iCACGP) since 2006. In 2010 she was elected as vice-president for iCACGP. At the University of Chile, she teaches courses on atmospheric chemistry, modeling and global change, inverse modeling, atmospheric science and introductory physics. She has guided multiple theses in engineering and atmospheric science in Chile. All in all, she has made original scientific contributions, and played a significant role in establishing atmospheric chemistry and modeling in her home country and internationally.

The Global Ocean Carbon Sink: Recent Trends and Variability

Nicolas Gruber
ETH Zürich, Switzerland

Since the onset of the industrial revolution in the late 18th century, the ocean has taken up about 30% of the total anthropogenic emissions of CO2, thereby constituting the most important sink for this CO2. While the annual rate of uptake has increased considerably over this period, largely in response to the increase in atmospheric CO2, there is considerable concern that this sink might saturate or even reverse in response to future climate change. Here, I present and discuss the most recent estimates of the oceanic sink strength for atmospheric CO2 and how this sink might have changed and varied in the recent decades. These estimates are based on two very complimentary sets of observations, i.e. (i) surface ocean observations of the partial pressure of CO2, from which monthly resolved global air-sea CO2 fluxes can be estimated for the period from 1980 onward, and (ii) ocean interior observations of dissolved inorganic carbon and ancillary properties, from which the accumulation of anthropogenic CO2 between the 1990s and the mid-2000s can be derived. The ocean interior results suggest a global increase in the anthropogenic CO2 inventory of about 25 Pg C between 1994 and 2006, while the cumulative air-sea CO2 flux over this period amounts to about 19 Pg C. Assuming a cumulative outgassing flux of ~5 Pg of “natural” carbon stemming from the carbon input by rivers, the global ocean interior and surface perspective are consistent with each other, suggesting a mean oceanic uptake flux of about 2.0 Pg C yr-1 over this period. This flux is at the lower end of most other estimates (e.g., atmospheric data and ocean inversions). If correct, the ocean sink would have been smaller than expected from the increase in atmospheric CO2. The surface ocean observations suggest that most of this lower than expected uptake stems from the Southern Ocean, whose sink strength was particularly weak in the 1990s. However, over the last decade, the Southern Ocean sink strength appears to have increased substantially, causing the global ocean uptake to increase commensurably. These substantial decadal variations and trends in the ocean carbon sink suggest that the sink strength could be more susceptible to the impact of future climate change than currently suggested by Earth System Models.

Nicolas Gruber

LNicolas Gruber (1968) holds a masters degree in environmental sciences from the Swiss Federal Institute of Technology (ETH) Zurich and received a Ph.D. from the University of Bern in 1997. Subsequently he worked as Visiting Research Scientist with the AOS program at the University of Princeton for three years. From 2000-2005 he was  an Assistant Professor at the Department of Atmospheric and Oceanic Sciences at the University of California, Los Angeles, where he received tenure in 2005. In 2006 he returned to Switzerland to become Professor for Environmental Physics at ETH Zurich. His main research interest are the global biogeochemical cycles of carbon and other biologically essential elements and their interaction with the climate system. He combines the analysis of observations with modeling studies to better quantify, for example, the fate of the anthropogenic CO2 emissions in the Earth system, particularly the uptake by the ocean and land biosphere. He authored together with Jorge Sarmiento the textbook “Ocean Biogeochemical Dynamics” that has become a standard text in the field. In recognition of his outstanding contribution to Marine Sciences, Dr. Gruber received the Rosenstiel Award from the Rosenstiel School of Marine and Atmospheric Sciences of the University of Miami in 2004. In 2012 he was elected fellow of the American Geophysical Union.




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