Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes

QPF performance of the updated SIMM forecasting system using reforecasts

International audienc

PRODUCTIVITY VERSUS PROMISED RESULTS - ONE OF THE DILEMMAS OF BIOTECHNOLOGY IN BRAZIL

In 1983 a new funding program - PADCT (''Programa de Apoio ao Desenvolvimento Cientifico e Tecnoldgico'') - was created in Brazil to stimulate the development of research projects related to what was established as technological priorities. In this paper 3 features of the Biotechnology/Health subprogram of PADCT were studied: a) to what extent productivity of the leaders of the research projects affected the way they were evaluated by the award panel, b) the conflict of interests that might result from the composition of the award panel, and c) the final impact of the program on science and technology. In our sample of 210 submitted projects, 62 were funded. The data suggest that the selection of projects did not ensure a better funding for the more productive research leaders. The presence on the award panel of at least one member from the same institution of a given project increased the chance of its approval but, after approval, it had no influence on the amount of funds granted. In a subsample of 21 scientists, support to 24 projects did not increase the productivity level and 4 products in a preliminary phase of development were reported. The issue of trying to solve problems in areas where there is no established scientific competence is discussed.27122709272

The Louvain-La-Neuve sea ice model LIM3.6: global and regional capabilities

International audienceThe new 3.6 version of the Louvain-la-Neuve sea ice model (LIM) is presented, as integrated in the most recent stable release of Nucleus for European Modelling of the Ocean (NEMO) (3.6). The release will be used for the next Climate Model Inter-comparison Project (CMIP6). Developments focussed around three axes: improvements of robustness, versatility and sophistication of the code, which involved numerous changes. Robustness was improved by enforcing exact conservation through the inspection of the different processes driving the air–ice–ocean exchanges of heat, mass and salt. Versatility was enhanced by implementing lateral boundary conditions for sea ice and more flexible ice thickness categories. The latter includes a more practical computation of category boundaries, parameterizations to use LIM3.6 with a single ice category and a flux redistributor for coupling with atmospheric models that cannot handle multiple sub-grid fluxes. Sophistication was upgraded by including the effect of ice and snow weight on the sea surface. We illustrate some of the new capabilities of the code in two standard simulations. One is an ORCA2-LIM3 global simulation at a nominal 2° resolution, forced by reference atmospheric climatologies. The other one is a regional simulation at 2 km resolution around the Svalbard Archipelago in the Arctic Ocean, with open boundaries and tides. We show that the LIM3.6 forms a solid and flexible base for future scientific studies and model developments

Sensitivity of the Global Ocean Carbon Sink to the Ocean Skin in a Climate Model

International audienceThe ocean skin is composed of thin interfacial microlayers of temperature and mass of less than 1 mm where heat and chemical exchanges are controlled by molecular diffusion. It is characterized by a cooling of ∼-0.2 K and an increase in salinity of ∼0.1 g/kg (absolute salinity) relative to the water below. A surface observation-based air-sea CO2 flux estimate considering the variation of the CO2 concentration in these microlayers has been shown to lead to an increase in the global ocean sink of the anthropogenic CO2 by +0.4 PgC yr-1 (15% of the global sink). This study analyzes this effect in more details using a 15-year (2000-2014) simulation from an Earth System Model (ESM) that incorporates a physical representation of the ocean surface layers (diurnal warm layer and rain lenses) and microlayers. Results show that considering the microlayers increases the simulated global ocean carbon sink by +0.26 to +0.37 PgC yr-1 depending on assumptions on the chemical equilibrium. This is indeed about 15% of the global sink (2.04 PgC yr-1) simulated by the ESM. However, enabling the ocean skin adjustment to feedback on ocean carbon concentrations reduces this increase to only +0.13 (±0.09) PgC y-1. Coupled models underestimate the ocean carbon sink by ∼5% if the ocean skin effect is not included

NEMO ocean engine

The ocean engine of NEMO is a primitive equation model adapted to regional and global ocean circulation problems. It is intended to be a flexible tool for studying the ocean and its interactions with the others components of the earth climate system over a wide range of space and time scales