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Boulder City, CO, United States

Haywood A.M.,University of Leeds | Dowsett H.J.,U.S. Geological Survey | Dolan A.M.,University of Leeds | Rowley D.,University of Chicago | And 7 more authors.
Climate of the Past | Year: 2016

The Pliocene Model Intercomparison Project (PlioMIP) is a co-ordinated international climate modelling initiative to study and understand climate and environments of the Late Pliocene, as well as their potential relevance in the context of future climate change. PlioMIP examines the consistency of model predictions in simulating Pliocene climate and their ability to reproduce climate signals preserved by geological climate archives. Here we provide a description of the aim and objectives of the next phase of the model intercomparison project (PlioMIP Phase 2), and we present the experimental design and boundary conditions that will be utilized for climate model experiments in Phase 2. Following on from PlioMIP Phase 1, Phase 2 will continue to be a mechanism for sampling structural uncertainty within climate models. However, Phase 1 demonstrated the requirement to better understand boundary condition uncertainties as well as uncertainty in the methodologies used for data-model comparison. Therefore, our strategy for Phase 2 is to utilize state-of-the-art boundary conditions that have emerged over the last 5 years. These include a new palaeogeographic reconstruction, detailing ocean bathymetry and land-ice surface topography. The ice surface topography is built upon the lessons learned from offline ice sheet modelling studies. Land surface cover has been enhanced by recent additions of Pliocene soils and lakes. Atmospheric reconstructions of palaeo-CO2 are emerging on orbital timescales, and these are also incorporated into PlioMIP Phase 2. New records of surface and sea surface temperature change are being produced that will be more temporally consistent with the boundary conditions and forcings used within models. Finally we have designed a suite of prioritized experiments that tackle issues surrounding the basic understanding of the Pliocene and its relevance in the context of future climate change in a discrete way. © 2016 Author(s).

Masson-Delmotte V.,CEA Saclay Nuclear Research Center | Stenni B.,University of Trieste | Pol K.,CEA Saclay Nuclear Research Center | Braconnot P.,CEA Saclay Nuclear Research Center | And 15 more authors.
Quaternary Science Reviews | Year: 2010

Climate models show strong links between Antarctic and global temperature both in future and in glacial climate simulations. Past Antarctic temperatures can be estimated from measurements of water stable isotopes along the EPICA Dome C ice core over the past 800 000 years. Here we focus on the reliability of the relative intensities of glacial and interglacial periods derived from the stable isotope profile. The consistency between stable isotope-derived temperature and other environmental and climatic proxies measured along the EDC ice core is analysed at the orbital scale and compared with estimates of global ice volume. MIS 2, 12 and 16 appear as the strongest glacial maxima, while MIS 5.5 and 11 appear as the warmest interglacial maxima. The links between EDC temperature, global temperature, local and global radiative forcings are analysed. We show: (i) a strong but changing link between EDC temperature and greenhouse gas global radiative forcing in the first and second part of the record; (ii) a large residual signature of obliquity in EDC temperature with a 5 ky lag; (iii) the exceptional character of temperature variations within interglacial periods. Focusing on MIS 5.5, the warmest interglacial of EDC record, we show that orbitally forced coupled climate models only simulate a precession-induced shift of the Antarctic seasonal cycle of temperature. While they do capture annually persistent Greenland warmth, models fail to capture the warming indicated by Antarctic ice core δD. We suggest that the model-data mismatch may result from the lack of feedbacks between ice sheets and climate including both local Antarctic effects due to changes in ice sheet topography and global effects due to meltwater-thermohaline circulation interplays. An MIS 5.5 sensitivity study conducted with interactive Greenland melt indeed induces a slight Antarctic warming. We suggest that interglacial EDC optima are caused by transient heat transport redistribution comparable with glacial north-south seesaw abrupt climatic changes. © 2009 Elsevier Ltd.

Construction and demolition waste is the second largest source of waste, after mining, in Sweden (30%), and when many concrete buildings that were built in the 1960s and 70s, the Million Programme, soon will be renovated the waste stream is expected to increase. But even though the amount of the waste is vast, only about half of the waste is recycled. The most common materials in the waste (soils and dredge spoils excluded) are wood, metal, plastics and concrete. As a recycled material concrete is most commonly used as fill material in road constructions. In the project Constructivate, initiated by CCR (Competence Centre Recycling) with funding from the Mistra programme Cloosing the loop, the participants, including the CCR-members Chalmers University of Technology, Chalmers Industriteknik, Renova, Stena Recycling, NCC, SP, Swerea and IVL will increase the recycling rate and specifically aim for the types of materials that today are not seen as something worth to recycle. Chalmers is represented by the division of Construction management at the Department of Civil and environmental engineering and the division of Energy and materials at the department of Chemistry and chemical engineering. At Chemistry and chemical engineering Ulf Jäglid and Rikard Ylmén are exploring the possibilities in recycling concrete in a way that is sustainable, both economically and environmentally. "We are investigating if it is possible to crush the concrete and find out how active it is. Normally there is around 10% of active components left in the demolition material that yet hasn't reacted with water and that be used once again as a cementing material," says Ulf Jäglid. To get to this you have to remove stone and rebars from the concrete. Another possible way is to reverse the production process, and instead of mixing cement, water and ballast, which results in concrete, remove these materials from each other. "That is the dream, to create such reversibility. That the process can be made both ways," says Ulf Jäglid. A third way is to standardise the concrete in buildings, so that they, like pieces of Lego, can be put together in different constructions and taken apart. The most important thing, according to Ulf Jäglid, is that the method must be working on the market and thereby may be implemented. One of the greater benefits you get from recycling concrete is that the CO2-emissions may be reduced, since much CO2 is produced in the making of new cement when calcium carbonate is burnt. Sweden is world leading when it comes to research in concrete recycling and now when representatives from the whole value chain is involved in CONSTRUCTIVATE the knowledge exchange between academia and industry will strengthen this position. The project also contains an extensive life cycle analysis, which makes it more likely that the results will be used. The roll of the chemists in the project is to contribute with knowledge at a molecular level. The art of building with concrete has been known for more than 2000 years, but what happens with the atoms and molecules is still relatively unknown. Now when the concrete is to be broken down as efficiently as possible, knowledge in chemistry is necessary. "Without knowledge in concrete chemistry it is difficult to optimise the recycling. We will take the process a step further by explaining what actually happens. If we know what we have, we also know what to do to start a reaction. Concrete is a very complex material so if we don´t know what we have, then we can make tests for a hundred years without finding the right method," Ulf Jäglid says. Explore further: From downcycling to recycling: Using lighting to separate cement particles from stone

Sienel T.,Heat Transfer and Advanced Systems | Heinbokel B.,CCR | Huff H.,Carrier Commercial Refrigeration CCR
ASHRAE/NIST Refrigerants Conference: Moving Towards Sustainability | Year: 2012

CO2 as a refrigerant for commercial refrigeration systems in Europe has been gaining increasing customer acceptance and market penetration since being introduced on the market almost a decade ago. The high efficiency of CO2 in commercial refrigeration systems at lower ambient conditions coupled with the relatively low number of hours these systems operate at high ambient conditions in mid to northern Europe have made these systems attractive from an energy efficiency perspective. The very low Global Warming Potential (GWP) of CO2 when compared with typical refrigerants used in these systems coupled with the relatively high leakage rates for typical commercial refrigeration systems have made CO2 very attractive from an environmental perspective. Data is showing that the performance of these systems is increasing year over year as more attention is paid to system design, commissioning, and maintenance. In order for these systems to become competitive globally, the energy efficiency of these systems must become competitive with incumbent refrigerants in higher ambient conditions. There are a number of technology options at various stages of maturity which show a path to achieving this goal. © 2012 ASHRAE.

Haywood A.M.,University of Leeds | Dowsett H.J.,U.S. Geological Survey | Otto-Bliesner B.,CCR | Chandler M.A.,Columbia University | And 10 more authors.
Geoscientific Model Development | Year: 2010

In 2008 the temporal focus of the Palaeoclimate Modelling Intercomparison Project was expanded to include a model intercomparison for the mid-Pliocene warm period (3.29-2.97 million years ago). This project is referred to as PlioMIP (Pliocene Model Intercomparison Project). Two experiments have been agreed upon and comprise phase 1 of PlioMIP. The first (Experiment 1) will be performed with atmosphere-only climate models. The second (Experiment 2) will utilise fully coupled ocean-atmosphere climate models. The aim of this paper is to provide a detailed model intercomparison project description which documents the experimental design in a more detailed way than has previously been done in the literature. Specifically, this paper describes the experimental design and boundary conditions that will be utilised for Experiment 1 of PlioMIP. © 2013 Author(s).

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