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Data and scripts used for the paper 'A global census of the significance of giant mesopelagic protists to the biogeochemical cycles of carbon and silicon' authored by: Manon Laget, Laetitia Drago, Thelma Panaïotis, Rainer Kiko, Lars Stemmann, Andreas Rogge, Natalia Llopis-Monferrer, Aude Leynaert, Jean-Olivier Irisson, Tristan Biard

Ocean alkalinity enhancement (OAE) is currently discussed as a potential negative emission technology to sequester atmospheric carbon dioxide in seawater. Yet, its potential risks or cobenefits for marine ecosystems are still mostly unknown, thus hampering its evaluation for large-scale application. Here, we assessed the impacts OAE may have on plankton communities, focusing on phytoplankton and microzooplankton. In a mesocosm study in the oligotrophic subtropical North Atlantic, we investigated the response of a natural plankton community to CO2-equilibrated OAE across a gradient from ambient alkalinity (2400 μmol kg-1) to double (4800 μmol kg-1). Abundance and biomass of phytoplankton and microzooplankton were insensitive to OAE across all size classes (pico, nano and micro), nutritional modes (autotrophic, mixotrophic and heterotrophic) and taxonomic groups (cyanobacteria, diatoms, haptophytes, dinoflagellates, and ciliates). Consequently, plankton communities under OAE maintained their natural chlorophyll a levels, size structure, taxonomic composition and biodiversity. These findings suggest a high tolerance of phytoplankton and microzooplankton to CO2-equilibrated OAE in the oligotrophic ocean. However, alternative application schemes involving more drastic perturbations in water chemistry and nutrient-rich ecosystems require further investigation. Nevertheless, our study on idealized OAE will help develop an environmentally safe operating space for this climate change mitigation solution.

Sowohl beim Ausbau erneuerbarer Energien als auch im Bereich der Elektromobilitat hat sich die Bundesregierung ambitionierte Ziele gesetzt. Im Kontext der Energiewende soll der Anteil fluktuierender erneuerbarer Energien an der Stromerzeugung weiter deutlich steigen. Dies erfordert tendenziell eine erhohte Vorhaltung von Regelleistung. Gleichzeitig sinkt die Stromerzeugung aus thermischen Kraftwerken, die bisher einen grosen Teil der Regelleistung vorgehalten haben. Vor diesem Hintergrund wird untersucht, welche Rolle eine angenommene Flotte von 4,4 Millionen Elektrofahrzeugen im Jahr 2035 bei der Bereitstellung von Regelleistung in Deutschland spielen konnte. Dabei werden zwei verschiedene Szenarien des Kraftwerksparks sowie unterschiedliche Moglichkeiten der Bereitstellung von Regelleistung mit und ohne Ruckspeisung elektrischer Energie von den Fahrzeugbatterien in das Stromnetz untersucht. Berechnungen mit einem hierfur weiterentwickelten, quellenoffenen Simulationsmodell zeigen, dass die Elektrofahrzeugflotte einen nennenswerten Beitrag zu einer kostengunstigen Regelleistungsvorhaltung leisten kann. Dies gilt auch dann, wenn keine Ruckspeisung von den Fahrzeugbatterien in das Stromnetz moglich ist. Unter Basisannahmen fallen hingegen die Arbitrageaktivitaten am Groshandelsmarkt sehr gering aus. Auch die Systemkosteneinsparungen sind im Vergleich zu einem rein kostenoptimalen Laden der Fahrzeugbatterien relativ niedrig. Unter alternativen Annahmen zur Zusammensetzung des Kraftwerksparks und zu den Batterieabnutzungskosten kann es dagegen zu nennenswerten Arbitrageaktivitaten am Groshandelsmarkt, zu einer noch hoheren Regelleistungsbereitstellung und zu wesentlich groseren Systemkosteneinsparungen kommen.

As the largest renewable electricity source, hydropower represents an alternative to fossil fuels to achieve a low-carbon future. However, increasing evidence suggests that hydropower reservoirs are an important source of biogenic greenhouse gases (GHGs), albeit with large uncertainties. Combining spatially resolved assessments of GHG fluxes and hydroelectric capacity databases, we assessed that global GHG emissions from reservoirs is 0.38 Pg CO2 eq.yr−1, accounting for 1.0% of global anthropogenic emissions. The median carbon intensity for hydropower is ∼63.0 kg CO2eq. MWh−1, which is lower than that for fossil fuels, but higher than that for other renewable energy sources. High carbon intensity is mostly linked to shallow (water storage depth <20 m) and eutrophic reservoirs. Furthermore, we found that the reservoir carbon intensity (CI) value would be markedly increased to 131.5 kg CO2eq. MWh−1 when considering the dams under construction and planning. A low-carbon future will benefit from optimal dam planning and management measures, i.e., applying sludge removal treatments, thereby reducing the proportion of shallow reservoirs and anthropogenic pollution.

Having barely registered an increase at the beginning of the new millennium, during the economic upturn after 2009, there was significant growth in the mileage by registered motor vehicles in Germany, both in the case of utility vehicles and automobiles. Overall, in 2011, automobiles covered a higher mileage than ever before. Despite more efficient engines, this resulted in fuel consumption stagnating in recent years, although the long-term trend is one of decline. With an 85-percent share of total mileage, automobiles dominate our roads. This transport demand pattern is predominantly created by the needs of private households and it is currently in a state of flux when it comes to gender and age balance. Women's growing presence in education and on the labor market has, in turn, resulted in an increase in their car ownership and mileage. At the same time, men and women are maintaining a more mobile lifestyle by retaining their cars into older age. However, more limited car use has been observed, particularly among young people who, more frequently than previously, seem to be opting for the most suitable form of transport rather than traveling exclusively in their own vehicles.

Abstract We apply an approach that theoretically connects processes at different scales within a sociotechnical sustainability transitions frame, focusing on individual actors. Drawing on interviews with actors involved in the electric mobility transition in Lower Saxony, Germany, we analyse actors’ narratives as revelatory of situated or ‘conjunctural’ knowledge, as viewed from a strong structuration perspective of sociotechnical change. The purpose is to shed a particular type of light on structure-agency processes. Strong structuration is an extended version of Giddens’ social theory that takes account of actors’ subjective experience of their situation, viewing this as both shaped by - and shaping of - structure, in the sense of rules that are internal and external to individuals. Here we show how actors’ narratives of their experiences and positions in the sociotechnical system reveal themes relevant to the on-going structuration electric vehicles in the case study region of Lower Saxony, Germany. We identify general ‘meta-narratives’ that span more than one individual, as well as personal narratives that are specific to individuals. In addition, the analytic value of narratives in transition literature is discussed.

Electrification and automatization may change the environmental impact of vehicles. Current eco-driving approaches for electric vehicles fit the electric power of the motor by quadratic functions and are limited to powertrains with one motor and single-speed transmission or use computationally expensive algorithms. This paper proposes an online nonlinear algorithm, which handles the non-convex power demand of electric motors. Therefore, this algorithm allows the simultaneous optimization of speed profile and powertrain operation for electric vehicles with multiple motors and multiple gears. We compare different powertrain topologies in a free-flow scenario and a car-following scenario. Dynamic Programming validates the proposed algorithm. Optimal speed profiles alter for different powertrain topologies. Powertrains with multiple gears and motors require less energy during eco-driving. Furthermore, the powertrain-dependent correlations between jerk restriction and energy consumption are shown.

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the "global carbon budget" – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on land-cover change data and bookkeeping models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of our imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2007–2016), EFF was 9.4 ± 0.5 GtC yr−1, ELUC 1.3 ± 0.7 GtC yr−1, GATM 4.7 ± 0.1 GtC yr−1, SOCEAN 2.4 ± 0.5 GtC yr−1, and SLAND 3.0 ± 0.8 GtC yr−1, with a budget imbalance BIM of 0.6 GtC yr−1 indicating overestimated emissions and/or underestimated sinks. For year 2016 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1. Also for 2016, ELUC was 1.3 ± 0.7 GtC yr−1, GATM was 6.1 ± 0.2 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1 and SLAND was 2.7 ± 1.0 GtC yr−1, with a small BIM of −0.3 GtC. GATM continued to be higher in 2016 compared to the past decade (2007–2016), reflecting in part the higher fossil emissions and smaller SLAND for that year consistent with El Niño conditions. The global atmospheric CO2 concentration reached 402.8 ± 0.1 ppm averaged over 2016. For 2017, preliminary data indicate a renewed growth in EFF of +2.0 % (range of 0.8 % to 3.0 %) based on national emissions projections for China, USA, and India, and projections of Gross Domestic Product corrected for recent changes in the carbon intensity of the economy for the rest of the world. For 2017, initial data indicate an increase in atmospheric CO2 concentration of around 5.3 GtC (2.5 ppm), attributed to a combination of increasing emissions and receding El Niño conditions. This living data update documents changes in the methods and data sets used in this new global carbon budget compared with previous publications of this data set (Le Quéré et al., 2016; 2015b; 2015a; 2014; 2013). All results presented here can be downloaded from https://doi.org/10.18160/GCP-2017.