Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Tuesday 7 July - 17:00-18:30 UPMC Jussieu - ROOM 201 - Block 24/34

1106 - The Earth’s energy imbalance and exchanges at the atmosphere-ocean interface: from fundamental research to societal concern

Parallel Session

Lead Convener(s): K. Von Schuckmann (Mediterranean Institute of Oceanography, La Garde, France), C. Guieu (CNRS-UPMC, Villefranche sur mer, France)

Convener(s): K. Trenberth (National Center for Atmospheric Research, Boulder, Colorado, United States of America), E. Brévière (GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany)

17:00

Earth's energy imbalance: current knowledge and future challenges

M. Palmer (Met Office, Exeter, United Kingdom)

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Earth's energy imbalance: current knowledge and future challenges

M. Palmer (1)
(1) Met Office, Hadley Centre, Exeter, United Kingdom

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Anthropogenic climate change arises from the accumulation of excess solar energy in the Earth system through increases in heat-trapping greenhouse gases associated with human activities. The various aspects of observed climate change (surface temperature rise, increased rainfall rates, loss of glaciers, global sea level rise, changes in climatic extremes) are all symptoms of this accumulation of energy, of which > 90% is manifested in increased ocean heat storage. The rate of climate change is defined by Earth's energy imbalance (EEI) and this represents the most fundamental quantity for monitoring ongoing global warming.

Ultimately, the impacts of climate change will be determined by the future evolution of EEI and how this additional energy interacts with the flows of energy within the Earth system. In this talk, I will outline the scientific motivation for better monitoring of EEI and review the recent progress that has been made through improved Earth system observations. I will discuss the future challenges in improving our estimates of this critical aspect of global change and advocate for EEI and ocean heat storage becoming central to both our thinking and communication on climate change. 

17:20

SOLAS, a decade of international research at the air-sea interface: main accomplishments and future goals

C. Guieu (CNRS-UPMC, Villefranche sur mer, France)

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SOLAS, a decade of international research at the air-sea interface: main accomplishments and future goals

C. Guieu (1)
(1) CNRS-UPMC, Villefranche sur mer, France

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The surface ocean and lower atmosphere domain is a complex, highly dynamic component of the Earth system. Air-sea fluxes of biogeochemically-active materials and energy exert a major impact on global biogeochemistry and climate. Some of the largest uncertainties in projecting future global environmental trends are attributable to an insufficient understanding of the physical and biogeochemical interactions and feedbacks between the ocean and atmosphere (IPCC, 2013).

The overarching goal of SOLAS (Surface Ocean-Lower Atmosphere Study) international program launched in 2004, is to achieve a quantitative understanding of the key biogeochemical-physical interactions and feedbacks between the ocean and atmosphere, and how this coupled system affects and is affected by global change. Our understanding of the exchanges of energy, gases and particles at the atmosphere-ocean interface has advanced over the past decade but there are still large uncertainties to adequately parameterize fundamental controlling processes as identified in the new research strategies of the international SOLAS group (Law et al., 2013). In this context, the scientific questions driving SOLAS research are highly challenging, inherently multidisciplinary, and broad in scope. They include: (1) What controls the ocean/atmosphere exchange of climate-relevant gases and particles? (2) How does the atmospheric deposition of materials impact ocean biogeochemistry? (3) What are the links between ocean biology, aerosols, and clouds? (4) What are the biogeochemical controls on emissions of highly reactive gases that impact atmospheric photochemistry and stratospheric ozone?

Climate mitigation policies based on greenhouse gas budgets must take into account the role of ocean-atmosphere fluxes for future projections. In that context, several of the geoengineering schemes currently debated for climate mitigation are directly linked to the ocean-atmosphere system, including ocean iron fertilization, sea spray generators, ocean foams, and modification of the ocean upwelling. Informed assessment of their feasibility, efficacy and potentially unintended effects will derive from SOLAS science.

This presentation will overview the SOLAS 2004-2014 goals and main accomplishments and present the SOLAS 2015-2025 rationale and scientific scope. 

17:40

Origin of the Recent Tropical Atlantic SST warming: the role of ocean dynamics?

J. Servain, (IRD/UMR-182, Paris, France), G. Caniaux (CNRM/GAME (Météo-France/CNRS), TOULOUSE, France), A. Hounsou-Gbo (Universidade de Pernambouco, Recife, Brazil), Y. Kouadio (University Felix Houphouet Boigny - Cocody - Abidjan, Abidjan, Ivory Coast), M. Mcphaden (NOAA, Seattle, United States of America), M. Araujo (Universidade de Pernambouco, Recife, Brazil)

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Origin of the Recent Tropical Atlantic SST warming: the role of ocean dynamics?

J. Servain, (1) ; G. Caniaux (2) ; A. Hounsou-Gbo (3) ; Y. Kouadio (4) ; M. Mcphaden (5) ; M. Araujo (3)
(1) IRD/UMR-182, Locean, Paris, France; (2) CNRM/GAME (Météo-France/CNRS), TOULOUSE, France; (3) Universidade de Pernambouco, Departamento de oceanografia, Recife, Brazil; (4) University Felix Houphouet Boigny - Cocody - Abidjan, Physic, Abidjan, Ivory Coast; (5) NOAA, Pmel, Seattle, United States of America

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During the last decades, the sea surface temperatures (SSTs) of the whole tropical Atlantic has substantially increased. Since the 1960s, the mean SST series of the tropical Atlantic [30°N-20°S, 60°W-15°E] has gained some 0.8°C. Moreover, when considering the main break points which affect the time series, the most significant trend occurred since 1995, at a rate of 0.25°C per decade for the whole basin.  When regionalyzed, the most severe warming affects the north-western part of the basin with values up to 1°C, as well as the coastal upwelling regions offshore Africa. Surprisingly the trade wind system, that drives the equatorial upwellings, strengthened since the 1960s and specially since the 1980s. These changes has been established by considering various independent observational data sets, allowing to prove the robustness of the results.

The origin of the SST change has been investigated by analyzing the changes of the air-sea surface fluxes and of the water column by considering integral quantities like sea level anomalies and upper level heat contents. It appears that the SST warming is not directly related to the local surface heat fluxes, which tend to increase the ocean heat loss. This implies that the signal is not coming from the atmosphere but rather from the ocean itself, i.e. due to recent changes in the ocean dynamics. Moreover, lagged correlation patterns between heat content and SSTs, suggest the existence of a relationship between the SST warming and the circulation in the northern tropical Atlantic.  Finally, several hypotheses are presented to conciliate both the strengthening of the wind-stress, the SST and upper-water warming, as well as the break point dates which affect the trends.

18:00

Oceanic biotic components, production mechanism of organic aerosol in Marine Boundary Layer ans cloud-climate system

M. C. Facchini (National Research Council (CNR), Bologna , France), C. D. O'dowd (National University of Ireland Galway, Galway, Ireland), R. Danovaro (Polytechnic University of Marche, Ancona, Italy)

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Oceanic biotic components, production mechanism of organic aerosol in Marine Boundary Layer ans cloud-climate system

MC. Facchini (1) ; CD. O'dowd (2) ; R. Danovaro (3)
(1) National Research Council (CNR), Institute of Atmospheric Sciences and Climate (ISAC), Bologna , France; (2) National University of Ireland Galway, School of physics and centre for climate & air pollution studies, ryan institute, Galway, Ireland; (3) Polytechnic University of Marche, Department of life and environmental sciences, Ancona, Italy

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Studies performed during the past years strongly suggest that biogenic organic compounds play an important role in submicron marine aerosol chemical composition over biologically productive, high latitude, marine regions, in both hemispheres and new biogenic oceanic sources of primary and secondary origin of OA were revealed. We discuss on the global importance of biogenic OA marine sources and their high spatial and temporal variability and the complex interaction with gaseous biogenic precursors and oceanic biotic components (Phytoplankton, viruses and bacteria). Submicron marine organic aerosol are a complex mixture of biogenic materials transferred from the ocean surface by the sea spray or by oxidative gas to particle conversion of volatile organics emitted by decomposition processes of oceanic dissolved organic carbon.   The role of marine biota on the evolution of plankton bloom and on the partitioning of oceanic organic carbon in POC and DOC reservoirs and  transfer mechanisms into MBL will be discussed.

18:20

Poster presentations

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Poster presentations
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